edited be report.docx

Bansilal Ramnath Agarwal Charitable Trust’s

Vishwakarma Institute of Technology (An Autonomous Institute affiliated to University of Pune)

DEPARTMENT OF MECHANICAL ENGINEERING

A PROJECT REPORT ON

“DESIGN AND FABRICATION OF AN ELECTRIC FOLDABLE CYCLE”

Submitted in the partial fulfillment of the requirements

for the degree of

Bachelor of Mechanical Engineering

SUBMITTED BY

OMAR LATIFI GR. NO. 101013

REWATI KULKARNI GR. NO. 101069

SHAIKH KASHIF GR. NO. 081356

GUIDED BY

PROF. D. B. HULWAN

2013-2014

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Bansilal Ramnath Agarwal Charitable Trust’s

Vishwakarma Institute of Technology (An Autonomous Institute affiliated to University of Pune)


CERTIFICATE

This is to certify that the project entitled


Is a bonafide work carried out by




Students of B.E. (Mechanical Engineering) during the academic year 2013-14 under the

supervision and guidance of Prof. D. B. Hulwan and it is approved for the partial fulfillment of

the requirements of University of Pune, for the award of the Degree of Bachelor of Engineering

(Mechanical Engineering).

Prof. D. B. Hulwan Prof. H. G. Phakatkar (Project Guide) (Head – Dept. of Mechanical Engg.)

1 | P a g e VISHWAKARMA INSTITUTE OF TECHNOLOGY

DESIGN ENGINEERING

Vishwakarma Institute of Technology

Pune-411037

2012-2013


The project report entitled


By




is approved in the partial fulfillment on the requirements

for the degree of

Bachelor of Mechanical Engineering

Examiner Project Guide (Prof. D. B. Hulwan)


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ACKNOWLEDGEMENT

It is with immense pleasure that we present to you our project titled,

“Design and fabrication of an electrical foldable cycle”

We take this opportunity to express our gratitude and sincere thanks to all those who

directly or indirectly have contributed in matters related to this project.

We wish to thank our project guide Prof. D. B. Hulwan of Mechanical Engineering

Department for helping us throughout this project. His continuous support and advice have

contributed tremendously towards bringing this project to fruition.

We also thank Mr. Chavan, workshop guide at Vikas Steels Pvt. Ltd. and Mr. Mande at

Asset Engineers Pvt. Ltd.,, for allowing us to undertake this project under their practical

guidance and for sharing his rich experience and valuable knowledge with us.

We also thank Prof. H. G Phakatkar, Head of Mechanical Engineering Department for his

kind co-operation.

Date: 21th May, 2014

Omar Latifi Rewati Kulkarni

Shaikh Kashif


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ABSTRACT

Design Engineering is the agenda hold by almost every national and multinational company to survive in the fierce competition of today’s commercial market. India is a country where cost is most significant factor for manufacturing and sale of products. To achieve this, we have followed multiple mechanical research design tools and procedures.

Using related and unrelated stimuli methods along with brain storming helped us invent multiple viable solutions which fully satisfy all functional requirements as specified by an average modern-day city bicycle commuter. To indentify most accurate solution or rather, most inexpensive design, we used different elimination methods and ultimately came up with our final grand solution. After finalization of the design, we drafted it for manufacturing.

The main changes we implemented in this new product were change in product design and type of folding mechanism. We identified and implemented our new design in such a way that the final product is as optimized in terms of design feasibility, manufacturing cost, and overall functionality.


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TABLE OF CONTENTS Page No.

1. Survey 022. History of Folding Cycle 033. Usage and Functionality 074. Components 09

4.1. Description of Components4.2. Frame Geometry

5. Classification of Foldable cycles 135.1. Half or Mid fold5.2. Triangle Hinged5.3. V clamp Hinge

6. Our concept 156.1. Changes in concept6.2. Dynamics of the bicycle6.3. Force Calculations6.4. Analysis (FEA)

7. Electric drivetrain 447.1. Overview 7.2. Technical specifications7.3. Design variations7.4. Product description and characteristics

8. Costing of hub motor kit 57 8.1. Advantages & Disadvantages

9. Machining 60

9.1. Milling9.2. Turning9.3. CNC

10. Cost Analysis 6610.1. On parts procured from market10.2. On parts manufactured10.3. Comparison

11. Alternative superior materials for enhanced performance 6912. Photographs of manufacturing process 7113. Conclusion 7714. Final rendering of model 78 15. Bibliography of references 79


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IMAGE GLOSSARY Page no.

1. First foldable bicycle by William Gout 03

2. The Latta foldable cycle 04

3. Folding cycle by Micheal B Ryan 05

4. The Faun folding cycle 06

5. Frame components of a regular cycle 09

6. Dahon half fold cycle 14

7. Anemos triangle hinge fold cycle 14

8. Design of V-clamp hinge 15

9. Design of main frame 16

10. Connection of swing arm with outermost shaft of pedal assembly 18

11. Folding mechanism of the rear 18

12. Folding mechanism of the front 21

13. Basic bicycle model 23

14. Basic diamond frame explaining chief geometric parameters 25

15. Schematic for yaw motion 26

16. (a & b) Rear views for roll motion 27

17. Schematic explaining lean and steer angles 29

18. Schematic of rolling resistance on wheel 32

19. Contact force during instant of force calculation on wheel 32

20. Schematic of application of pedaling force 34

21. Schematic of all components of pedaling force 34

22. Linkage for leg, position controlled, pedal-crank system 35

23. Schematic of chief forces acting on a bicycle 36

24. Equivalent stress on the frame (design 1) 37

25. Total deformation of the frame (design 1) 38

26. Schematic of forces on swing arm 38


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27. Total deformation of frame (design 2) 39

28. Equivalent stress on frame (design 2) 39

29. Equivalent stress on whole bicycle 42

30. Total deformation of bicycle 42

31. Anatomy of an electric bicycle 49

32. Electric hub motor 51

33. Drafting of electric hub motor 52

34. Exploded view of electric hub motor 53

35. Wiring layout 54

36. Battery pack 55

37. Drafting of battery pack 56

38. Proposed cost of the electric hub motor kit 57

39. Turning operations 63

40. CNC machine 64

INDEX OF TABLES

1. Table 1: Cost analysis of market procured components 66

2. Table 2: Cost analysis for manufactured components 67

3. Table 3: Cost analysis comparing materials/components used 68

against superior materials/components

DRAFTING GLOSSARY

1. Swing arm assembly 19

2. Front fork assembly 22

3. Main frame with J-groove slot 40


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4. Bicycle assembly 43

SURVEY

Design Engineering is taught as the core of any engineering body of knowledge as a technique in which the design of a system is optimized by crafting a mix of performance (function) and costs. In most cases this practice identifies and removes unnecessary expenditures, thereby increasing the aesthetic and ergonomic function for the manufacturer and/or their customers

Keeping this view in mind we intended our interest for design engineering and tried our efforts to create a unique daily usage application project where we can deal with cost effective products which can enhance the customer’s requirement without affecting its functional operation and thereby reducing the undesirable property, ‘cost’ which is present day’s want.

It started with searching of different types of foldable cycles and their difference in design, under the guidance of Prof. D.B Hulwan.

We accepted our challenges and we expressed our interest to work with processes with a view to learn application based knowledge and enhancement of engineering skills.

The project of our foldable cycle with an electric hub motor hence commenced.


http://en.wikipedia.org/wiki/Optimization_(mathematics)

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HISTORY OF FOLDING CYCLES

You might think that folding bikes have just been invented lately in the last couple of decades. The truth is, the very first invention of folding bike can be traced back to as far as the 19th century! History of folding bikes is an interesting story to look at. Followings are some important milestones in the history of folding bicycles:

The very first inventor of folding bike was never known for sure. However there were some documented inventions about the “first ever” folding bicycles that can be found around the late 19th century.

In 1878 William Grout from England invented the first portable bicycle, which some gave credit as the first ever “folding” bike although this is not exactly accurate.


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Fig 1: First Foldable Cycle by William Grout

In 1888, Emmit G. Latta filed the first patent of what looks like a true folding bike. The patent was later sold to a company called Pope Manufacturing Company. However no existing product of this patent has been found so it might or might not have been manufactured and sold by Pope.

Fig 2: The Latta foldable cycle


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In 1893, another American inventor called Michael B. Ryan filed another widely known patent for his folding bike invention. Some regarded this as the first ever folding bike invention.


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Fig 3: Folding Cycle by Michael B Ryan

Another folding bike invention which sometimes claimed to be the first folding bike was invented by William Crowe in 1896. The patent was sold later to Faun Bicycle Company.


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Fig 4: Faun Folding CycleUSAGE AND FUNCTIONALITY

How a folding bicycle can work for you

Airplanes

Private pilots and travelers across the country enjoy the convenience and portability of a Citizen Bike.

Stowed conveniently in the hold of even the smallest aircraft, a folding bike still leaves room for other gear. So, wherever you may land, Citizen Bike has you covered for your on-land adventure.

Boats

Boaters love the flexibility and convenience of having a Citizen Bike on board. Pull into port, pull out your folding bikes and have a full featured bicycle to take you wherever you want to go.

Citizen Bike Folding Bikes are bicycles that fold simply to fit compactly into the hold of a boat. Exploring the inland or just doing errands to and from town, Citizen Bike has a model that will fit your riding requirements and fold to fit in your boat.

Car

You can take your bicycle with you without the hassle of a bike rack! Whether it's a business trip, a camping trip or just a weekend drive in the country, store your folding bike in your trunk and have the freedom to go for a ride whenever you want. A Citizen Bike can fold to fit in the trunk of a compact car. Whatever your vehicle: sedan, SUV, truck, etc, in less than 30 seconds your bike can be locked safely in the back – no tools, no roof rack, no hassle.

RV

Whether you are cruising across the canyons in your motorhome, meandering across the plains with your trailer or just away for a weekend of rural retreat in your camper, a Citizen Bike


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folding bike offers you the flexibility to take your bikes with you without the hassle or eye-sore of an external bike carrier. A Citizen Bike can be folded into a carrying case and tucked out of the way, clean and dry, leaving you plenty of room for your other gear.

Commuting

Avoid the jams in the city. Keep fit on your journey to work. A Citizen Bike is easy to carry in elevators and can be stored snugly into a closet or under your desk at work. Take your folding bike on the train and make those final blocks to work on your bike. Store your folding bike in your trunk for sunny days when you can park in a remote lot and bike the rest of the way to work.

Storage

Whether you are a city dweller, a student or just space constrained, a Citizen Bike offers you a great ride with the added convenience of portability and easy storage. You do not have to leave your bike in the hall or outside. A Citizen Bike folding bike can be folded neatly into a carrying case and stored out of the way in a closet.


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COMPONENTS

Fig 5: Frame Components of a Regular cycle

Head tube

The head tube contains the headset, the bearings for the fork via its steerer tube. In an integrated headset, cartridge bearings interface directly with the surface on the inside of the head tube, on non-integrated headsets the bearings (in a cartridge or not) interface with "cups" pressed into the head tube.

Top tube

The top tube, or crossbar, connects the top of the head tube to the top of the seat tube.

In a traditional-geometry diamond frame, the top tube is horizontal (parallel to the ground). In a compact-geometry frame, the top tube is normally sloped downward toward the seat tube for additional standover clearance. In a mountain bike frame, the top tube is almost always sloped downward toward the seat tube. Radically sloped top tubes that compromise the integrity of the traditional diamond frame may require additional gusseting tubes, alternative frame construction, or different materials for equivalent strength.

Step Through frames usually have a top tube that slopes down steeply to allow the rider to mount and dismount the bicycle more easily. Alternative step-through designs may include leaving out


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the top tube out completely, as in monocoque mainframe designs using a separated or hinged seat tube, and twin top tubes that continue to the rear fork ends as with the Mixte frame. These alternatives to the diamond frame provide greater versatility, though at the expense of added weight to achieve equivalent strength and rigidity.

Control cables are routed along mounts on the top tube, or sometimes inside the top tube. Most commonly, this includes the cable for the rear brake, but some mountain bikes and hybrid bicycles also route the front and rear derailleur cables along the top tube.

The space between the top tube and the rider's groin while straddling the bike and standing on the ground is called clearance. The total height from the ground to this point is called the height lever.

Down tube

The down tube connects the head tube to the bottom bracket shell. On racing bicycles and some mountain and hybrid bikes, the derailleur cables run along the down tube, or inside the down tube. On older racing bicycles, the shift levers were mounted on the down tube. On newer ones, they are mounted with the brake levers on the handlebars.

Bottle cage mounts are also on the down tube, usually on the top side, sometimes also on the bottom side. In addition to bottle cages, small air pumps may be fitted to these mounts as well.

Seat tube

The seat tube contains the seatpost of the bike, which connects to the saddle. The saddle height is adjustable by changing how far the seatpost is inserted into the seat tube. On some bikes, this is achieved using a quick release lever. The seatpost must be inserted at least a certain length; this is marked with a minimum insertion mark.

The seat tube also may have braze-on mounts for a bottle cage or front derailleur.

Chain stays

The chain stays run parallel to the chain, connecting the bottom bracket shell to the rear fork ends or dropouts. When the rear derailleur cable is routed partially along the down tube, it is also routed along the chain stay. Occasionally (principally on frames made since the late 1990s) mountings for disc brakes will be attached to the chain stays. There may be a small brace that connects the chain stays in front of the rear wheel and behind the bottom bracket shell.


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Chain stays may be designed using tapered or untapered tubing. They may be relieved, ovalized, crimped, S-shaped, or elevated to allow additional clearance for the rear wheel, chain, crankarms, or the heel of the foot.

Seat stays

Example of a dual-stay seat stay system.

The seat stays connect the top of the seat tube (often at or near the same point as the top tube) to the rear fork dropouts. A traditional frame uses a simple set of paralleled tubes connected by a bridge above the rear wheel. When the rear derailleur cable is routed partially along the top tube, it is also usually routed along the seat stay.

Many alternatives to the traditional seat stay design have been introduced over the years. A style of seat stay that extends forward of the seat tube, below the rear end of the top tube and connects to the top tube in front of the seat tube, creating a small triangle, is called a Hellenic stay after the British frame builder Fred Hellens, who introduced them in 1923. Hellenicseat stays add aesthetic appeal at the expense of added weight. This style of seat stay was popularized again in the late 20th century by GT Bicycles (under the moniker "triple triangle"), who had incorporated the design element into their BMX frames, as it also made for a much stiffer rear triangle (an advantage in races); this design element has also been used on their mountain bike frames for similar reasons.

Another common seat stay variant is the wishbone, single seat stay, or mono stay, which joins the stays together just above the rear wheel into a monotube that is joined to the seat tube. A wishbone design adds vertical rigidity without increasing lateral stiffness, generally an undesirable trait for bicycles with unsuspended rear wheels. The wishbone design is most appropriate when used as part of a rear triangle subframe on a bicycle with independent rear suspension.

A dual seat stay refers to seat stays which meet the front triangle of the bicycle at two separate points, usually side-by-side.

Fastback seat stays meet the seat tube at the back instead of the sides of the tube.

On most seat stays, a bridge or brace is typically used to connect the stays above the rear wheel and below the connection with the seat tube. Besides providing lateral rigidity, this bridge provides a mounting point for rear brakes, fenders, and racks. The seat stays themselves may also be fitted with brake mounts. Brake mounts are often absent from fixed-gear or track bike seat stays.


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Bottom bracket shell

The bottom bracket shell is a short and wide tube, relative to the other tubes in the frame, that runs side to side and holds the bottom bracket. It is usually threaded, often left-hand threaded on the right (drive) side of the bike to prevent loosening by fretting induced precession, and right-hand threaded on the left (non-drive) side. There are many variations, such as an eccentric bottom bracket, which allows for adjustment in tension of the bicycle's chain. It is typically larger, unthreaded, and sometimes split. The chain stays, seat tube, and down tube all typically connect to the bottom bracket shell.

There are a few traditional standard shell widths (68, 70 or 73 mm). Road bikes usually use 68 mm; Italian road bikes use 70 mm; Early model mountain bikes use 73 mm; later models (1995 and newer) use 68 mm more commonly. Some modern bicycles have shell widths of 83 or 100 mm and these are for specialised downhill mountain biking or snowbiking applications. The shell width influences the Q factor or tread of the bike. There are a few standard shell diameters (34.798 – 36 mm) with associated thread pitches (24 - 28 tpi).

FRAME GEOMETRY

The length of the tubes and the angles at which they are attached define frame geometry. In comparing different frame geometries, designers often compare the seat tube angle, head tube angle, (virtual) top tube length, and seat tube length. To complete the specification of a bicycle for use, the rider adjusts the relative positions of the saddle, pedals and handlebars:

Saddle height, the distance from the center of the bottom bracket to the point of reference on top of the middle of the saddle.

Stack, the vertical distance from the center of the bottom bracket to the top of the head tube.

Reach, the horizontal distance from the center of the bottom bracket to the top of the head tube.

Bottom bracket drop, the distance by which the center of the bottom bracket lies below the level of the rear hub.

Handlebar drop, the vertical distance between the references at the top of the saddle to the handlebar.


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Saddle setback, the horizontal distance between the front of the saddle and the center of the bottom bracket.

Stand over height, the height of the top tube above the ground.

Front center, the distance from the center of the bottom bracket to the center of the front hub.

Toe overlap, the amount that the feet can interfere with steering the front wheel.

The geometry of the frame depends on the intended use. For instance, a road bicycle will place the handlebars in a lower and further position relative to the saddle giving a more crouched riding position; whereas a utility bicycle emphasizes comfort and has higher handlebars resulting in an upright riding position.

Frame geometry also affects handling characteristics. For more information, see the articles on bicycle and motorcycle geometry and bicycle and motorcycle dynamics.

TYPES OF FOLDABLE CYCLES

Folding bikes are an excellent solution to the some of the problems that cyclists can face in an urban environment. Although they are not suited to longer journeys, they're very well-suited for short hops. Folding bikes do not have the storage problems that non-folding bikes do – by folding up, they take up much less space, requiring only small areas for storage. Most folding bikes are designed to fit under your desk at work. For this reason, they are also ideal for carrying on public transport.Folding bikes look a little strange until you get used to them – although they use smaller wheels than normal bikes (often 20 inch diameter wheels, as opposed to the 26 or more inches that most non-folding bikes use), the wheels are placed in such a way that the bike is the same distance end to end as a non-folding bike. However, the frame is generally much lower to the ground, and some parts of the bike, such as seat poles and handlebar stem, are greatly elongated to compensate for this – up to four times the normal length of such parts, and designed to telescope in and out.

The odd appearance of the folding bike is for a very good reason, though. They are designed in such a way that the position of the rider is the same as it would be on a normal bike. Likewise, the gearing is designed to compensate for the folding bike's different positioning, so that it will feel the same as a normal bike.


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There are several different kinds of folding bike, with the major distinction between them being the manner in which a given bike folds. There are two major types of hinge – swing hinges and flip hinges – and different combinations and numbers of these hinge types are responsible for most of this variety. Folding mechanisms generally involve quick releases and latches, although some manufacturers use cable-activated systems.

Half or mid fold Many folding frames follow classic frame pattern of the safety bicycle's diamond frame, but feature a hinge point (with single or double hinges) allowing the bicycle to fold approximately in half. Quick-release clamps enable raising or lowering steering and seat columns. A similar swing hinge may be combined with a folding steering column. Fold designs may use larger wheels, even the same size as in non-folders, for users prioritizing ride over fold compactness. Bikes that use this kind of fold include Dahon, Tern, and Montague.

Fig 6: Dahon Half Fold Cyle

Triangle hinged folding bikes usually allow the rear triangle of the bike’s frame to be folded down. Many triangle folding bikes also feature other parts that fold, typically either the steering column, the front forks, or both. A hinge in the frame may allow the rear triangle and wheel to be folded down and flipped forward, under the main frame tube, as in the Swift Folder and Bike Friday. Such a flip hinge may be combined with a folding front fork as in the Birdy. Swing and flip hinges may be combined on the same frame, as in Brompton and Dahon, which use a folding steering column. Folding mechanisms typically involve latches and quick releases, which affect the speed of the fold/unfold. Bike Friday offers a model, the Tikit, featuring a cable-activated folding mechanism requiring no quick releases or latches, for increased folding speed.


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Fig 7: Triangle Hinged Anemos Cycle

The V-clamp hinge uses a large, stainless steel plate as the locking mechanism. When the lever is pulled on the opposite side of the frame, the plate clamps around both sides of the hinge snugly. This covers the largest surface area of any hinge, maximizing safety and durability.

In addition, the V-clamp hinge can be tightened using an Allen key on the outside of the plate. There is also a DoubleLok safety hinge that keeps the lever from opening regardless of how you ride the bike. It's really one of the best locking systems for folding bicycles.

Fig 8: V clamp Hinge


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OUR CONCEPT

We based our frame on a popularly used design on upright bicycles, known as the diamond frame, which is a truss containing two triangles: the front triangle and the rear triangle.

Traditionally, the front triangle consist of the head tube, the top tube, down tube and seat tube, while the rear triangle consists of the seat tube and the chain stays paired along with the seat stays.

In modifying the abovementioned design, we have adopted a continuous contour of the frame by means of using two parallely placed plates, instead of using a tubing type structure. The purpose of this design was to accommodate the front and rear folds, while giving the folded bicycle a clean appearance, wherein, the folded components would be integral within the frame.

The process of zeroing in on an ideal frame shape happened in accordance and in tandem with the modification we created for the existing system of a triangle hinge fold. A conventional triangle hinge fold includes a hinge incorporated in the framework, which may allow the rear triangle and wheel to be folded down and flipped forward under the main frame tube. A folding steering column may also be used, and the whole mechanism involves the use of quick releases and latches.

Hence, the modified frame was created to look like this:


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Fig 9: Design of the main frame

CHANGES IN CONCEPT:

As mentioned in the previous section, the folding mechanism employed on our prototype is a variation of a traditional triangle hinge fold. The following points depict clearly how we have brought about this change:

1. Swing arm:

The connection from the main frame to the rear wheel is generally made by means of another tubular structure which branches into two, extends from the main framework, and acts as supporting members for the wheel and hub assembly. This is also known as the rear suspension of the bicycle.

The simplest form of a rear suspension, known as the single pivot suspension, consists of a rear axle held by a swing arm, which is connected to the frame by a single pivot point located near the bottom bracket. Not only is there ease of construction involved in this design, but it served our purpose of achieving the rear folding mechanism.

The rear folding mechanism:


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The innovation in terms of the rear folding mechanism, involved the design and incorporation of a J-groove slot on the right (with respect to rider orientation) plate of the frame.

The swing arm was welded off centred to the right side, onto the outermost shaft of the pedal assembly.

This shaft, being a part of the pedal assembly, has complete rotational movement about its own axis. This means that the swing arm welded onto the shaft also rotates along with the shaft, as one body. This subsequent vertical motion of the swing arm meant that it could be rotated clockwise (with respect to front view) into the frame and made to fit in, by using a locking mechanism to keep it in position.

Hence, the J-groove locking method was incorporated in our design, and the width between the two frame plates was maintained while accounting for the space requirements of the wheel assembly.

This can be better understood from the following figures:

Fig10: Connection of the swing arm with the outermost shaft of the pedal assembly


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Fig 11: Direction of rear folding mechanism


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Drafting 1: Swing arm assembly


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2. Front fork:

The bicycle fork is the component that holds the front wheel and allows the rider to steer and balance the bicycle. Typically, bicycle forks consist of two blades which join at a common point called a crown (above the top surface of the wheel), and this continues into a single steering tube. The rider controls steering using handlebars, which are attached to the stem. The steering tube of the fork interfaces with the main frame via a head tube, which houses the headset, supported by bearings.

A variation of the fork that is most often used in mountain bikes is called the monofork. As the name suggests, this type of fork consists of a single blade, and is also called a suspension fork. These bikes make use of linear needle roller bearings to transmit steering torque to the wheel, and the fork is attached to the wheel by a specially designed hub.

The front folding mechanism:

The fork we have designed is a monofork. However, since our bicycle is designed only with a specific flat-terrain purpose in mind, we have chosen to exclude the use of shock absorbers inside the fork.

The design consists of a head tube, through which passes the steering tube. The difference in design exists where the steering tube is offset to the left (as viewed from rider’s orientation) side, so as to align with the rear swing arm (which is offset to the right side), and hence stabilise the bicycle.

The headset is a circular shaft made to fit through diametrically opposite holes drilled in the head tube, and through the frame, in a direction that is perpendicular to the plane of the frame. The ends of the shaft have been fit with deep groove ball bearings, and finished by covering with end caps.

The steering tube is fixed to the head tube, by means of taper roller bearings. Hence, the fork is free to swivel about these two points of fixture, and by a clockwise motion, it is thus folded inside the frame. For this reason, the frame too has been designed, so as to accommodate the curvature of the wheel.


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This can be better understood from (Fig 12):

Fig 12: Direction of folding of the front fork


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Drafting 2: Front fork assembly


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EXPLAINING THE MOTION:

The mathematical description of bicycle handling is a challenging task, even if simplifying assumptions are made. Aerodynamics, weight, stability, ergonomics, ease of handling, comfort, durability, stiffness and biomechanics are some of the aspects considered in the designing of a bicycle.

The Cornell Bicycle Research Project was created to apply scientific techniques to the engineering problems of a bicycle. The goal was to shed light on long-standing questions and develop engineering approaches and tools that would lead to better bikes.

The inclusion of factors such as rider behaviour, frame flexibility, and sophisticated tire phenomena rapidly transforms the mathematics into the realm of computer simulations, and takes the problem away from usable practical guidelines available to design engineers.

On the lines of the analysis performed by the CBRP, and for the purpose of ease of calculation and understanding, we elected to work with a basic bicycle model that consists of rigid knife-edge hard wheels, a frame which is only subjected to deformation due to reactions at the supports (rear, pedal bracket, and front), a rigidly mount rider, and a rigid steerable front fork, including the front wheel, stem, and the handlebar. (Fig13)

Fig 13: Basic bicycle model (image courtesy- Bicycle Dynamics, The Meaning behind the Math, by John Olson and Jim Papadopoulos, PhD.)


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Prior to performing any analysis, or tabulating any calculated data, we took into consideration the following assumptions, over and above the aforementioned assumption of a basic bicycle body:

A) The bicycle-rider system is symmetric about the vertical plane passing lengthwise through the middle of the main frame. Hence, when the bike is in vertical equilibrium position, the wheel axles are perpendicular to the main frame, the steering axis is in the plane of the frame, the wheel contacts are on the plane, and all mass is assumed to be symmetrically distributed in this plane.

B) The wheels are rotationally symmetric about their axles.

C) There is no friction or pedaling torque between the wheels and the axle or frame.

D) All equations considered are linear and velocity is assumed to be constant in the forward direction.

E) Lateral load at wheels is such that no slip will occur between the wheel and the ground.

The external forces applied to the body are:

A) Vertical body force due to gravityB) Vertical reaction force from the ground at the point of contact between the wheel and

ground.C) Lateral load at the base of the wheel from road contact.D) Drag force acting on the frontal region of the frame, caused by air resistance, while

accounting for the constant speed of travel.

While performing real-time analysis, any basic bicycle with stiff, non-slipping tires has three instantaneous degrees of freedom: roll, steer, and forward motion.

To simplify this presentation, the forward velocity v is taken as a constant. It is also assumed that the wheels always just touch the ground. As far as the tire itself is concerned, the simplest model is accounted for, i.e., the pure rolling of a disc. The last two conditions eliminate sideways wheel forces from the governing equations.


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DYNAMICS OF THE BICYCLE (STABILITY):

The dynamic considerations of a bicycle are accounted for from the point of view of the stability of the bicycle. It was not possible for us to measure the parameters mentioned below, or used in the equations, since we were not equipped with the suitable measuring equipment. However, we have made suitable assumptions from a theoretical point of view, and with more sophisticated design and manufacturing methods, we will be able to translate them better into practicality.

The figure (Fig 14) shows the important geometric parameters used in the calculation of roll, steer and yaw motion of the bicycle:

ABCx

y

z

a

b

h

Fig 14: Geometry of basic diamond frame bicycle with important parameters (image courtesy- Dynamic Model of a Bicycle from Kinematic and Kinetic consideration, by Andrew Davol, PhD,

P.E, and Frank Owen, PhD, P.E, California Polytechnic State University)

Where the given parameters are:

A = origin of the system a = wheel base h = height of centre of mass above the ground b = distance between origin and centre of mass in the horizontal direction β = head tube angle Δ = trail B = contact point of wheel on ground C = intersection of steering axis with ground


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Yaw motion:

According to the figure (Fig 15), let the bicycle move in the left direction, with a constant velocity v and let the front fork be deflected through an angle α. If the tires track true, i.e., move only with straight and forward rolling motion, then the velocity of the frame is in the x direction, and the velocity of the front fork is in direction of the front wheel, so α is to the left of the x axis. These two velocity directions fix the location of the instant centre. The bike rotates around the instant centre and this rotation represents a direction change, hence it is yaw.

η= vR

The following figure (Fig 15) helps explain the geometry:

B A

y

xz

R

R/ c os

In s ta n tC e n te r

a

Fig 15: Geometry for yaw motion


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Hence,

a= Rcos α

sin α And, R=a/α (assuming sinα and cosα both = 1)

(the value of the steer angle α, for a leisure touring bike is around 23-24 degrees)

Roll motion:

From the figures (Fig 16{a} and Fig 16{b})shown below, we can say that the bicycle roll represents a negative rotation about the x-axis.

A

xy

z

A

xy

za aa

h

Fig 16(a): Rear view, with roll angle Fig 16(b): Rear view with sideways acceleration

The bicycle undergoes the following accelerations:

a θ̈ - Roll acceleration. If angular velocity varies, this value changes accordingly. This is a tangential acceleration.


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a η̇ - Normal acceleration towards centre of turn. Associated with direction of change of velocity, hence its value is never zero, even on a circular path.

a η̈ - Yaw acceleration. If yaw varies, this value varies accordingly. This means that the curve followed by the bike is not constant but either tightens or slackens.

The values of these accelerations can be written in the form of equations as:

a θ̈=hθ̈ ,

a η̇=v2

R , a η̈=b η̈

Imagine the steady state condition where the steering angle is constant (α̇=0 ) and the roll angle is constant (θ̇=0 andθ̈=0 ). Then we get:

Mg sin θ=M v2

R

This represents the state where the bicycle is travelling around in a circle (with centripetal

acceleration, v2

R , or “centrifugal force”, M v2

R ) at a constant roll angle. The weight tending to roll the bicycle inward toward the centre of the circle is counteracted by the “centrifugal force” tending to make the bike roll over to the outside.


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GYROSCOPIC EFFECTS:

A common belief is that gyroscopic effects by themselves are what make a bicycle stable.

That there are gyroscopic forces is evident from the riderless bicycle test in which a bicycle is shoved at a brisk speed (from another bicycle) and allowed to coast on its own. If the initial course is straight, the bicycle will continue this path until it slows to a speed where gyroscopic forces are too small to correct steering. Then the bicycle takes a steep turn as it falls.

To understand the contribution of gyroscopic effects, we may consider the following scenario, using the concept of lean and steer from the figure (Fig 17) shown:

Fig 17: Schematic explaining lean, θ (left-right movement of frame about vertical plane through frame), and steer, α (left-right movement of front wheel with vertical plane containing frame)

Extending the above example of a riderless bicycle, let us add another condition to it; let the bicycle lean right (positive θ). This causes the front wheel to steer right (positive α) due to a gyroscopic effect.

A torque would have to be applied on the handlebars in the left direction, to prevent the front wheel from steering right. Therefore, with torque absent, on a riderless bicycle, the front wheel naturally steers right.


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If that is the case, the bicycle then travels in a circular path (towards the right). This decreases θ due to the effect of centripetal acceleration. This in turn causes the bicycle to lean left (negative θ) which causes the front wheel to steer left (negative α), which then causes the bike to travel in a circular path (towards the left), once more due to the effect of centripetal acceleration. This decreases θ (bicycle leans right) which again causes the front wheel to steer right, and on and on. The same chain of events happens if the bicycle initially leans left (negative θ). This chain of events keeps the bicycle from falling over.

The entire physical interactions taking place are actually more complex than the scenario given above, especially due to oscillations in θ and α. But the simplified scenario given above serves to highlight the contribution that gyroscopic effects make in keeping a bicycle stable.


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FORCE CALCULATIONS:

As discussed in previous sections, we have calculated the chief forces acting on the bicycle, as follows:

i. The frontal portion of the bicycle along with the rider will experience the maximum amount of air or wind resistance, also known as drag. Although the drag force experienced is also caused by auxiliary factors such as the rider’s clothing, wind speed, shoes, density of air, etc, we neglect all such factors and thus have taken into account, chiefly, the frontal area upon which maximum resistance is offered, a constant air density of 1.226 kg/m3, and a constant riding speed of 18 km/h (i.e., 5.0 m/s).

Fdrag=12

× A × CD × ρ × v2

¿ 3.83 N

Where, A = frontal area (0.5 m2) CD = coefficient of drag (0.5)

ρ = density of air v = constant riding speed

ii. At the point where the wheels touch the road surface, there is also a resistive force offered by the ground in contact, and this is known as rolling resistance. This is a resistive force to the rolling motion of the wheels as the bicycle moves forward.

F rr=mT × g ×C rr

¿4.59N

Where, mT = mass of rider and bicycle together (78 kg) g = acceleration due to gravity (9.81 m/s2) Crr = coefficient of rolling resistance, dependent on type of road surface (0.006)


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Fig. 18: Schematic of rolling resistance force on wheel

Fig. 19: Depiction of effect of contact force on wheel during instant of force

calculation


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iii. Gravitational forces pull the bicycle and the rider system down a hill or a gradient slope. The slope of said hill is defined as the ratio of vertical rise to horizontal run. Here, we have taken a standard assumption of 0.03.

Fg=mT × g× gradient

¿22.95 Niv. The total power required by the rider to effectively overcome the net resistive

forces acting on the rider+bike system, is given by:

PR=(FD+F rr+F g)× v

¿156.85Watts

v. In order to effectively calculate pedal force, we first need to calculate the speed of the pedal. For this, we require the pedal cadence (revolutions of the pedal crank per minute), which is, roughly, the rate at which a cyclist is turning the pedals. The standard cadence value for recreational and utility cycling is within the range of 60-80 rpm, and for flat roads, it may go upto a range of 90-170 rpm. Hence, we selected an optimum value of 100 rpm.

vp=2 πl cd

60× 103

¿1.45 m/s

Where, vp = speed of pedal l = crank length (138.5 mm) cd = cadence (100 rev./min)

vi. The pedaling force is such that, when the force on the pedal is vertical (rider’s foot) and the crank (pedal) is horizontal, maximum torque is obtained from a constant force. A longer crank length will require less force on the pedal, but again, this length cannot be too long, or else, the pedal will interfere with the terrain, and cause drag.


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Fig 20: Schematic of application of pedaling force

Fig 21: Schematic of pedaling forces


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Fig 22: The linkage representing the leg plus the position-controlled pedal-crank system. (image courtesy- Forces in bicycle pedaling, by Jim Papadopoulos, Cornell University)

Hence, the average force on the pedals during one revolution can be calculated as:

Fav=PR

v p

¿108.17 N

The effective pedaling force, which gives the force in each of the two legs, that is required to give the same average force Fav, while pedaling only in portion (Eeff) of the full rotation of the pedals, is given by:

F eff=360 Fav

2 Eeff

¿278.15 N

Where, Eeff = portion angle of full rotation turned during pedaling (70o)


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ANALYSIS:

In conducting FEA, we analysed the frame for its design worthiness in terms of the equivalent stress and total deformation caused due to the forces applied. A schematic shown below gives a concise idea of the chief forces acting on any bicycle frame. The detailed description is as follows:

Fig 23: Schematic of chief forces acting on a bicycle


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The key force acting on the frame is the rider’s weight at the topmost portion of the seat post. In performing the FEA of the frame, the front and bottom bracket holes were kept fixed as supports, assuming an ideal no-shock ride, and a rigid system. A load of 700N was applied in the vertically downward direction, on the area of the seat.

F rider=m× g ¿686.7N 700 N

Where, m= mass of rider (maximum of 70 kg) g= acceleration due to gravity (9.81 m/s2)

The analysis gave us the following results:

Fig 24: Equivalent stress acting on the frame


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Fig 25: Total deformation of the frame

The frame is seen to be bulging in the outward direction, since there are no supports between the two plates in this scenario for analysis. The J-groove also has not been included, since our idea was to test the frame initially for the unique design, and its subsequent worthiness.

The swing arm, being a single bladed and offset member at the rear portion, was going to be the part of the rear frame that would be subjected to the most significant amount of loading, and thus, subsequent deformation and induced stress. Once the rider assumes his/her position on the bicycle, the swing arm would be subjected to loading in the following manner:

Fig 26: Schematic of forces on swing arm


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The loading of the swing arm when locked inside the J-groove would mean that the rider’s weight would be distributed over the frame as well be translated to the J-groove, and therefore, the extension of the swing arm. By analyzing the frame including the J-groove, we were able to find the deflection, and stress associated with the slot mechanism and hence, its design worthiness, with respect to the folding.

The results we obtained were as follows:

Fig 27: Total deformation of frame with J-groove slot

Fig 28: Equivalent stress on frame with J-groove slot


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Drafting 3: Main frame with J-groove slot


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From the above FEA, we observed that the frame was deforming significantly under the application of a constant pressure over the top surface, from the maximum possible load limit (70 kg), once the J-groove had been introduced.

The stress concentration and deformation in the region of the slot is very evident from the images. Hence, our solution to this was to add additional support members from the inside, running perpendicular to the two frames, after fitting the rest of the assembly. These members would also bear the load distribution on the bicycle, and cause less stress concentration towards the left edge of the frame.

Our methodology during the entire duration of designing and manufacturing our bicycle has been experimental with analytical validation, like most industrial bicycle designers who design new bicycle forms, commercially, or for experimental purposes. Hence, we have paid thorough scrutiny in the process of selection of materials and manufacturing of the bike, for good stability, ride quality, and durability. Since the FEA has been done, keeping in mind only the major forces on the bicycle, while neglecting several factors, and accounting for a change in end support conditions, the analytical data is bound to vary from the hardcore physical test results we have in hand.

We analysed the entire bicycle, applying all the maximum, optimized, ideal, and absolute forces calculated in the previous section. The results are as shown:


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Fig 29: Equivalent stress on the whole bicycle, under the effect of drag force, force due to rider mass, rolling resistance at wheels, and pedaling force.

Fig 30: Total deformation of the bicycle under the effect of drag force, force due to rider mass, rolling resistance at wheels, and pedaling force.


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Drafting 4: Bicycle assembly


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ELECTRIC DRIVETRAIN

The hybrid electric or fully electric drivetrain is now the most popular form of new drive train concept currently under development at most automotive companies. The success of such technology is largely due to the fact that almost all of the related sub-systems have been in operation for decades in other industries. Thus, outstanding performance and efficiency is expected within a short time to market.

As usual during such technology transition phase, the established combustion engine has remained the main energy source for hybrid vehicles. However, recent concepts indicate that this trend is due to fade out. The next years will bring a large variety of drivetrains, including purely electric vehicles.

Several core components of electric drive trains, like the electric motor, have been in operation for more than a century. Yet achieving a highly dynamic and efficient traction unit with mobile HV-energy storage, to be operated reliably under various climate conditions, is a significant challenge. Moreover, a strong OEM trend towards vertical technology integration demands electrics and electronics, control and high voltage technology, electro-chemistry to be integrated into the environment of vehicle development.

Challenges

Validation time :

Electric drivetrains are validated in distributed programs, which are run in parallel by the OEM plus several Tier 1 suppliers. Project management is even more demanding under these circumstances than in classical drivetrain projects. A systematic monitoring of the component maturity level is inevitable for keeping track on the demanding validation schedules. Common tools, like a centralized database for durability test definitions and test results are key to success.

Load profiles :

Varying customer preferences and usage profile can strongly influence the system load of hybrid drivetrain components, since two energy sources are available for vehicle traction. This is a major challenge to validation as the reference load spectra are no longer determined by the vehicle speed distribution. This demands a comprehensive and systematic investigation of actual field load profiles extended beyond SOP to gain satisfying statistics on vehicle operation.


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New components, new load cases :

Frequent switching between traction and generative braking is a good example for a new load case, which stresses the electric/electronic components. A systematic investigation into the corresponding failure modes delivers the basis for target oriented simulation and durability tests that are tailored toward reliability demonstration considering realistic load conditions.

Known components, new load cases :

Depending on the drivetrain concept, ICE components can be subject to drastic changes in load spectra (idle operation, motoring, starts frequency, quasi static operation, regenerative braking, etc.). Classical validation procedures typically do not address these features to the necessary extent.

Variants :Different drivetrain configurations are a major source of deficient reliability as their validation requirements quickly exceed available time and budget. For hybrid drivetrain designs this is aggravated by the additional variance in vehicle operation modes.

Solutions

Limitation of variants:

An important element is the assessment of co-validation, i.e. the transfer of validation results from a tested configuration to another variant. Taking-over of test results is justified only for parts, that are equal with respect to the failure modes under consideration. Therefore the careful tracking of parts-equivalence is required for this approach.

Failure modes:

The results of a detailed assessment of the potential failure modes affecting the drivetrain can be fed back to the product development to support design for reliability. Furthermore the correct understanding of the failure physics is a vital element for the definition of suitable tests and for design of the overall validation programs.

Field load profiles:

A careful assessment of the expected combined with understanding of the system control strategy also contributes to the design of effective tests.

Software:

Many of the techniques and solutions available at Uptime Engineering to support reliability optimization hybrid & electric drivetrains are included in the modules of our Uptime Solutions software.

Electric Bicycle


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An electric bicycle, also known as an e-bike, is a bicycle with an integrated electric motor which can be used for propulsion. There are a great variety of different types of e-bikes available worldwide, from e-bikes that only have a small motor to assist the rider's pedal-power (i.e., pedelecs) to somewhat more powerful e-bikes which tend closer to moped-style functionality: all, however, retain the ability to be pedaled by the rider and are therefore not electric motorcycles. E-bikes use rechargeable batteries and the lighter varieties can travel up to 25 to 32 km/h (16 to 20 mph), depending on the laws of the country in which they are sold, while the more high-powered varieties can often do in excess of 45 km/h (28 mph). In some markets, such as Germany, they are gaining in popularity and taking some market share away from conventional bicycles, while in others, such as China, they are replacing fossil fuel-powered mopeds and small motorcycles.

Classes of E-Bikes

E-bikes are classed according to the power that their electric motor can deliver and the control system, i.e., when and how the power from the motor is applied. Also the classification of e-bikes is complicated as much of the definition is due to legal reasons of what constitutes a bicycle and what constitutes a moped or motorcycle. As such, the classification of these e-bikes varies greatly across countries and local jurisdictions.

Despite these legal complications, the classification of e-bikes is mainly decided by whether the e-bike's motor assists the rider using a pedal-assist system or by a power-on-demand one. Definitions of these are as follows:

With pedal-assist the electric motor is regulated by pedaling. The pedal-assist augments the efforts of the rider when they are pedaling. These e-bikes – called pedelecs – have a sensor to detect the pedaling speed, the pedaling force, or both. Brake activation is sensed to disable the motor as well.

With power-on-demand the motor is activated by a throttle, usually handlebar-mounted just like on most motorcycles or scooters.

Therefore, very broadly, e-bikes can be classed as:1. E-bikes with pedal-assist only: either pedelecs (legally classed as bicycles) or S-Pedelecs

(often legally classed as mopeds) Pedelecs: have pedal-assist only, motor assists only up to a decent but not excessive

speed (usually 25 km/h), motor power up to 250 watts, often legally classed as bicycles

Pedelecs: have pedal-assist only, motor assists only up to a decent but not excessive speed (usually 25 km/h), motor power up to 250 watts, often legally classed as bicycles

2. E-bikes with power-on-demand and pedal-assist3. E-bikes with power-on-demand only: often have more powerful motors than pedelecs but

not always, the more powerful of these are legally classed as mopeds or motorcycles.


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Technical

Motors and drivetrains:The two most common types of hub motors used in electric bicycles are brushed and brushless. There are many possible types of electric motorized bicycles with several technologies available, varying in cost and complexity; direct-drive and geared motor units are both used. An electric power-assist system may be added to almost any pedal cycle using chain drive, belt drive, hub motors or friction drive. BLDC hub motors are a common modern design with the motor built into the wheel hub itself and the stator fixed solidly to the axle and the magnets attached to and rotating with the wheel. The bicycle wheel hub is the motor. The power levels of motors used are influenced by available legal categories and are often, but not always limited to under 750 watts.

Another type of electric assist motor, often referred to as the mid-drive system, is increasing in popularity. With this system, the electric motor is not built into the wheel but is usually mounted near (often under) the bottom bracket shell. In more typical configurations, a cog or wheel on the motor drives a belt or chain that engages with a pulley or sprocket fixed to one of the arms of the bicycle's crankset. Thus the propulsion is provided at the pedals rather than at the wheel, being eventually applied to the wheel via the bicycle's standard drive train.

Batteries:E-bikes use rechargeable batteries, electric motors and some form of control. Battery systems in use include sealed lead-acid (SLA), nickel-cadmium (NiCad), nickel-metal hydride (NiMH), lithium-ion polymer (Li-ion), lithium-iron phosphate (LiFePO4), and most recently, Lithium Manganese Cobalt (LiMnCo). Batteries vary according to the voltage, total charge capacity (amp hours), weight, the number of charging cycles before performance degrades, and ability to handle over-voltage charging conditions. The energy costs of operating e-bikes are small, but there can be considerable battery replacement costs. The lifespan of a battery pack varies depends on the type of usage. Shallow discharges will help extend the overall battery life.

Range is a key consideration with e-bikes, and is affected by factors such as motor efficiency, battery capacity, efficiency of the driving electronics, aerodynamics, hills and weight of the bike and rider. Some manufacturers, such as the Canadian BionX or American E+ (manufactured by Electric Motion Systems), have the option of using regenerative braking, the motor acts as a generator to slow the bike down prior to the brake pads engaging. This is useful for extending the range and the life of brake pads and wheel rims. There are also experiments using fuel cells. E.g. the PHB. Some experiments have also been undertaken with super capacitors to supplement or replace batteries for cars and some SUVS. E-bikes developed in Switzerland in the late 1980s for the Tour de Sol solar vehicle race came with solar charging stations but these were later fixed on roofs and connected so as to feed into the electric mains. The bicycles were then charged from the mains, as is common today.

Controllers


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There are two distinct types of controllers designed to match either a brushed motor or brushless motor. Brushless motors are becoming more common as the cost of controllers continues to decrease. (See the page on DC motors which covers the differences between these two types.)

Controllers for brushless motors: E-bikes require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally provide potentiometer-adjustable motor speed, closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.[38]

Controllers for brushed motors: Brushed motors are also used in e-bikes but are becoming less common due to their intrinsic lower efficiency. Controllers for brushed motors however are much simpler and cheaper due to the fact they don't require hall sensor feedback and are typically designed to be open-loop controllers. Some controllers can handle multiple voltages.

Design variations

Not all e-bikes take the form of conventional push-bikes with an incorporated motor, such as the Cytronex bicycles which use a small battery disguised as a water bottle. Some are designed to take the appearance of low capacity motorcycles, but smaller in size and consisting of an electric motor rather than a petrol engine. For example the Sakura e-bike incorporates a 200 W motor found on standard e-bikes, but also includes plastic cladding, front and rear lights, and a speedometer. It is styled as a modern moped, and is often mistaken for one.

Electric cargo bikes allow the rider to carry large, heavy items which would be difficult to transport without electric power supplementing the human power input.

Electric trikes have also been produced that conform to the e-bike legislation. These have the benefit of additional low speed stability and are often favored by people with disabilities. Cargo carrying tricycles are also gaining acceptance, with a small but growing number of couriers using them for package deliveries in city centres. Latest designs of these trikes resemble a cross-between a pedal cycle and a small van.


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Fig 31: Anatomy of an electric bicycle


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Environmental effects

E-bikes are zero-emissions vehicles, as they emit no combustion by-products. However, the environmental effects of electricity generation and power distribution and of manufacturing and disposing of (limited life) high storage density batteries must be taken into account. Even with these issues considered, e-bikes will have significantly lower environmental impact than conventional automobiles, and are generally seen as environmentally desirable in an urban environment.

The environmental effects involved in recharging the batteries can of course be minimized. The small size of the battery pack on an e-bike, relative to the larger pack used in an electric car, makes them very good candidates for charging via solar power or other renewable energy resources. Sanyo capitalized on this benefit when it set up "solar parking lots," in which e-bike riders can charge their vehicles while parked under photovoltaic panels.

The environmental credentials of e-bikes, and electric / human powered hybrids generally, have led some municipal authorities to use them, such as Little Rock, Arkansas with their Wavecrest electric power-assisted bicycles or Cloverdale, California police with Zap e-bikes. China’s e-bike manufacturers, such as Xinri, are now partnering with universities in a bid to improve their technology in line with international environmental standards, backed by the Chinese government who is keen to improve the export potential of the Chinese manufactured e-bikes.

A recent study on the environment impact of e-bikes vs other forms of transportation found that e-bikes are about:

18 times more energy efficient than an SUV 13 times more energy efficient than a sedan 6 times more energy efficient than rail transit And, of about equal impact to the environment as a conventional bicycle.

One major concern is disposal of used lead batteries, which can cause environmental contamination if not recycled.


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MagicPie 3 – Electric Hub Motor Kit

Fig 32: Electric Hub Motor

Programmable built-in controllerAccept versatile voltages: 24/36/48VRegenerative braking and cruise control60mm thin hub for common bike framesSupport disc-brake and 7-speed sprocketPower Rating: 500W-1000WWeight: 7.5 Kg’s (including internal controller)


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Fig 33: Drafting of Hub Motor


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Fig 34: Exploded view of hub motor


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Fig 35: Wiring Layout


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LiFePO4 Battery Pack for Electric Bikes 24V20AH/36V10AH/36V12AH/48V10AH

Fig 36: Battery Pack

Product Characteristics: Large and safe LiFePO4 cells inside Compact in size and light in weight (dimensions) BMS manages to each cell for high reliability Extra-long cycle life - 5 times life of Lead Acid and 2 times of NiMH Extremely safe: no explosion, no fire under collision, over charged or short circuit

Aluminum Casing with Switch/KeyBMS and 110V-240Vac 2A Universal Charger Included (optional 4A)Weight: below 5.5KgsCapacities: 24V/20AH, 36V/12AH, 36V/10AH, or 48V/10AHMax Discharge Current: 35A (12AH)/60A (16AH)Max Continuous Discharge Current: 20A (12AH)/30A (16AH)Charging Cycles: >800 timesRanges (full electric mode): 40Km (36V12AH) or 55Km (48V10AH)Packing Box Dimensions: 24cm X 24cm X 39cm


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Fig 37: Drafting of Battery Pack

COSTING

Fig 38: Proposed cost of the kit

Reason for infeasibility


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Due to insufficient funds, we weren’t able to incorporate the electric motor into our finished product.

Advantages & Disadvantages

Advantages

1.) Much Cheaper than GasOne of the biggest advantages of electric bicycles is that they're extremely affordable to operate. It costs less than a penny per mile to ride an electric bike or scooter. In comparison, it costs $0.15 per mile (on average) for gasoline alone - or 1500% more to operate a gas-powered vehicle. Add in license costs, insurance, registration, maintenance and other fees - and the cost skyrockets. According to U.S. Government figures, the average cost of driving and maintaining a motor vehicle in the United States is $0.54 per mile. More about the cost of operating an electric bike...

2.) Extended Range / Reduced StressWith the luxury of power assistance, you'll be able to pedal further and faster than you would on a normal bicycle. For this reason, electric bikes are great for commuting; whether it's to work or for a casual stroll through the neighborhood. Plus, you'll reduce both physical, and mental stress by avoiding traffic and other hazards associated with motor vehicles. Nothing beats the fresh air, cool breeze and sunshine on your face!

3.) Exercise is OptionalHaving the option to pedal is an advantage in two ways: First, if you'd like to move and get some exercise, you can pedal just like a normal bicycle. Although you can't pedal an electric scooter, an electric bike is very versatile and will allow you to use power; pedals; or both. In contrast, if you don't have the energy to pedal or don't want to get sweaty or exhausted - you can use power to assist you. If your electric bicycle has a throttle, there's no need for any pedaling at all - just twist and go.

4.) Safe and Easy to OperateElectric bikes and scooters are safe and easy to operate. Most e-bikes include intelligent safety features such as automatic power cut-off, and every product uses standard electrical safety components such as circuit breakers and fuses to protect riders. And unlike gasoline, there's no explosive danger with batteries. Limited speed also reduces the risk of fatal injuries in the event of an accident. Plus, you don't need to worry about a special license or insurance - electric bikes are classified as bicycles in most states.

5.) No Harmful Carbon EmissionsFor environmentally conscious individuals, the most important benefit of choosing electric-power is the positive impact on the environment. Unlike gas-guzzling vehicles, electric bicycles don't burn fossil fuels and release no harmful carbon emissions. Although power plants indirectly produce CO2 to charge the battery, it's impact is miniscule when compared to automobiles. Not


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only does lowering CO2 emissions reduce pollution and improve air quality, but it might also limit the effects of global warming.

Disadvantages

1.) Limited Range and SpeedMost electric powered bicycles and scooters are limited to a range of 15-40 miles per charge (depending on the model and battery type) so you won't be able to use an electric bike to go on long road trips or to drive extremely long distances. And since most electric bikes are limited to 20 mph or less, don't expect to get there immediately. Although you can avoid most road obstacles by riding a bike (i.e.: traffic, stop lights, intersections, etc.), it will still probably take a little longer to arrive at your destination.

2.) Less Security and ProtectionNaturally, you'll be less protected from harsh weather and adverse road conditions when riding a bike or scooter (of any type). Although you can operate these products in the rain, you'll definitely get wet without added protection. And depending on your location and seasonal weather patterns, your electric-powered bicycle or scooter might be completely side-lined for several months during the winter.


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MACHINING OF COMPONENTS

Definition:

Machining is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process. The many processes that have this common theme, controlled material removal, are today collectively known as subtractive manufacturing, in distinction from processes of controlled material addition, which are known as additive manufacturing. Exactly what the "controlled" part of the definition implies can vary, but it almost always implies the use of machine tools (in addition to just power tools and hand tools).

The precise meaning of the term machining has evolved over the past one and a half centuries as technology has advanced. In the 18th century, the word machinist simply meant a person who built or repaired machines. This person's work was done mostly by hand, using processes such as the carving of wood and the hand-forging and hand-filing of metal. At the time, millwrights and builders of new kinds of engines (meaning, more or less, machines of any kind), such as James Watt or John Wilkinson, would fit the definition. The noun machine tool and the verb to machine (machined, machining) did not yet exist. Around the middle of the 19th century, the latter words were coined as the concepts that they described evolved into widespread existence. Therefore, during the Machine Age, machining referred to (what we today might call) the "traditional" machining processes, such as turning, boring, drilling, milling, broaching, sawing, shaping, planing, reaming, and tapping. In these "traditional" or "conventional" machining processes, machine tools, such as lathes, milling machines, drill presses, or others, are used with a sharp cutting tool to remove material to achieve a desired geometry. Since the advent of new technologies such as electrical discharge machining, electrochemical machining, electron beam machining, photochemical machining, and ultrasonic machining, the retronym "conventional machining" can be used to differentiate those classic technologies from the newer ones. In current usage, the term "machining" without qualification usually implies the traditional machining processes.

Machining is a part of the manufacture of many metal products, but it can also be used on materials such as wood, plastic, ceramic, and composites. A person who specializes in machining is called a machinist. A room, building, or company where machining is done is called a machine shop. Machining can be a business, a hobby, or both. Much of modern day machining is carried out by computer numerical control (CNC), in which computers are used to control the movement and operation of the mills, lathes, and other cutting machines.

Machining processes used:


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I. Milling

Milling is a cutting process that uses a milling cutter to remove material from the surface of a work piece. The milling cutter is a rotary cutting tool, often with multiple cutting points. As opposed to drilling, where the tool is advanced along its rotation axis, the cutter in milling is usually moved perpendicular to its axis so that cutting occurs on the circumference of the cutter. As the milling cutter enters the work piece, the cutting edges (flutes or teeth) of the tool repeatedly cut into and exit from the material, shaving off chips (swarf) from the work piece with each pass. The cutting action is shear deformation; the metal is pushed off the work piece in tiny clumps that hang together to more or less extent (depending on the metal type) to form chips. This makes metal cutting a bit different (in its mechanics) from slicing softer materials with a blade.

The milling process removes material by performing many separate, small cuts. This is accomplished by using a cutter with many teeth, spinning the cutter at high speed, or advancing the material through the cutter slowly; most often it is some combination of these three approaches. The speeds and feeds used are varied to suit a combination of variables. The speed at which the piece advances through the cutter is called feed rate, or just feed; it is most often measured in length of material per full revolution of the cutter.

There are two major classes of milling process:

In face milling, the cutting action occurs primarily at the end corners of the milling cutter. Face milling is used to cut flat surfaces (faces) into the work piece, or to cut flat-bottomed cavities.

In peripheral milling, the cutting action occurs primarily along the circumference of the cutter, so that the cross section of the milled surface ends up receiving the shape of the cutter. In this case the blades of the cutter can be seen as scooping out material from the work piece. Peripheral milling is well suited to the cutting of deep slots, threads, and gear teeth.


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II. Turning

Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helical tool path by moving more or less linearly while the workpiece rotates. The tool's axes of movement may be literally a straight line, or they may be along some set of curves or angles, but they are essentially linear (in the nonmathematical sense). Usually the term "turning" is reserved for the generation of external surfaces by this cutting action, whereas this same essential cutting action when applied to internal surfaces (that is, holes, of one kind or another) is called "boring". Thus the phrase "turning and boring" categorizes the larger family of (essentially similar) processes. The cutting of faces on the workpiece (that is, surfaces perpendicular to its rotating axis), whether with a turning or boring tool, is called "facing", and may be lumped into either category as a subset.

Turning can be done manually, in a traditional form of lathe, which frequently requires continuous supervision by the operator, or by using an automated lathe which does not. Today the most common type of such automation is computer numerical control, better known as CNC. (CNC is also commonly used with many other types of machining besides turning.)

When turning, a piece of relatively rigid material (such as wood, metal, plastic, or stone) is rotated and a cutting tool is traversed along 1, 2, or 3 axes of motion to produce precise diameters and depths. Turning can be either on the outside of the cylinder or on the inside (also known as boring) to produce tubular components to various geometries. Although now quite rare, early lathes could even be used to produce complex geometric figures, even the platonic solids; although since the advent of CNC it has become unusual to use non-computerized tool path control for this purpose.

The turning processes are typically carried out on a lathe, considered to be the oldest machine tools, and can be of four different types such

as straight turning, taper turning, profiling or external grooving. Those types of turning processes can produce various shapes of materials such as straight, conical, curved, or grooved workpiece. In general, turning uses simple single-point cutting tools. Each group of workpiece materials has an optimum set of tools angles which have been developed through the years.

The bits of waste metal from turning operations are known as chips (North America), or swarf (Britain). In some areas they may be known as turnings.


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Fig 39: Turning Operations

III. CNC Machine


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Fig 40: CNC machine

Numerical control (NC) is the automation of machine tools that are operated by precisely programmed commands encoded on a storage medium, as opposed to controlled manually via hand wheels or levers, or mechanically automated via cams alone. Most NC today is computer numerical control (CNC), in which computers play an integral part of the control.

In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine via a post processor, and then loaded into the CNC machines for production. Since any particular component might require the use of a number of different tools – drills, saws, etc., modern machines often combine multiple tools into a single "cell". In other installations, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design.


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Description: Modern CNC mills differ little in concept from the original model built at MIT in 1952. Mills typically consist of a table that moves in the X and Y axes, and a tool spindle that moves in the Z (depth). The position of the tool is driven by motors through a series of step-down gears in order to provide highly accurate movements, or in modern designs, direct-drive stepper motor or servo motors. Open-loop control works as long as the forces are kept small enough and speeds are not too great. On commercial metalworking machines closed loop controls are standard and required in order to provide the accuracy, speed, and repeatability demanded.

As the controller hardware evolved, the mills themselves also evolved. One change has been to enclose the entire mechanism in a large box as a safety measure, often with additional safety interlocks to ensure the operator is far enough from the working piece for safe operation. Most new CNC systems built today are completely electronically controlled.

CNC-like systems are now used for any process that can be described as a series of movements and operations. These include laser cutting, welding, friction stir welding, ultrasonic welding, flame and plasma cutting, bending, spinning, hole-punching, pinning, gluing, fabric cutting, sewing, tape and fiber placement, routing, picking and placing (PnP), and sawing.

Examples of CNC machines:

Mills

CNC mills use computer controls to cut different materials. They are able to translate programs consisting of specific number and letters to move the spindle to various locations and depths. Many use G-code, which is a standardized programming language that many CNC machines understand, while others use proprietary languages created by their manufacturers. These proprietary languages while often simpler than G-code are not transferable to other machines.

Lathes

Lathes are machines that cut spinning pieces of metal. CNC lathes are able to make fast, precision cuts using indexable tools and drills with complicated programs for parts that normally cannot be cut on manual lathes. These machines often include 12 tool holders and coolant pumps to cut down on tool wear. CNC lathes have similar control specifications to CNC mills and can often read G-code as well as the manufacturer's proprietary programming language.

Plasma cutters

Plasma cutting involves cutting a material using a plasma torch. It is commonly used to cut steel and other metals, but can be used on a variety of materials. In this process, gas (such as compressed air) is blown at high speed out of a nozzle; at the same time an electrical arc is formed through that gas from the nozzle to the surface being cut, turning some of that gas to plasma. The plasma is sufficiently hot to melt the material being cut and moves sufficiently fast to blow molten metal away from the cut.


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COST ANALYSIS AND COMPARISON

Cost analysis of parts procured from market:

Part Quantity Cost MS Steel sheet1200x2200mm 1 2850BearingsSingle sided ball bearings 2 400Double sided ball bearings 2 4006005 grade taper bearings 2 750Stock PartsWheels 2 1000Crankset 1 300Chain 1 150Flywheel 1 250Pedals 1 100

Total : 6200

Table 1: Cost analysis (Market)


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Cost analysis of parts manufactured:

Part Description Machine/Process Time

(Hrs:Min)

Cost

FrameCutting of reqd. shape from the sheet

CNC plasma cutter 00:25 2800

Bend the sheet to reqd. angle

Bending machine 00:10 250

Shaft (x5)Cutting rod

Turning operation

Cutting machine

Lathe

00:10

00:35

200

1000Milling Lathe 00:20 300

ForkCutting rod Cutting machine 00:10 200Turning operation Lathe 00:30 500

Welding C02 arc welding 00:05 150Surface finish Grinding 00:15 50

SwingarmSurface finish the rect. Bar

Grinding 00:10 50

Cutting the bar Cutting machine 00:05 100Welding CO2 arc welding 00:05 150Final surface finish

Grinding 00:10 50

Total Amount: 5800

Table 2: Cost Analysis (Manufacturing)


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Cost comparison with alternative material:

Part Materials used Alternate materialFrame MS Steel sheet(CN19)

1200x2400mm

Aluminum sheet(Grade19000)

1200x2400mmCost 2850 4080Wheels Standard aluminum alloy rim

with stainless steel spokes

(F,R)

Revenge™ Carbon fiber rim with magnesium alloy spokes

(F,R)

Cost 1000 9371Crankset Standard single speed crankset SRAM S100 1.1 165mm x 48t

Track / Fixed Gear Bike Powerspline Crank Set

Cost 340 4500Chain Standard stainless steel chain Sram red chain 1091 RCost 150 1000Electric hub motor Not used MagicPie™3 Electric hub

motor kitCost - 29332Battery Not used LiFePO4 Battery Pack

48V10AHCost - 38423Total : 4340 86706

Table 3: Cost Analysis (Comparison)


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ALTERNATIVE SUPERIOR MATERIALS FOR ENHANCED PERFORMANCE

Carbon Fiber:

Carbon-fiber-reinforced polymer, carbon-fiber-reinforced plastic or carbon-fiber reinforced thermoplastic (CFRP, CRP, CFRTP or often simply carbon fiber, or even carbon), is an extremely strong and light fiber-reinforced polymer which contains carbon fibers.

The binding polymer is often a thermoset resin such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester or nylon, are sometimes used. The composite may contain other fibers, such as aramid e.g. Kevlar, Twaron, aluminium, or glass fibers, as well as carbon fiber. The properties of the final CFRP product can also be affected by the type of additives introduced to the binding matrix (the resin). The most frequent additive is silica, but other additives such as rubber and carbon nanotubes can be used. CFRPs are commonly used in the transportation industry; normally in cars, boats and trains, and in sporting goods industry for manufacture of bicycles, bicycle components, golfing equipment and fishing rods.

Although carbon fiber can be relatively expensive, it has many applications in aerospace and automotive fields, such as Formula One racing and wherever high strength-to-weight ratio and rigidity are required such as sailing boats and rowing shell hulls, top-end bicycles and motorcycles, As manufacturing techniques improve and costs reduce it is becoming increasingly common in small consumer goods that require strength, lightness and stiffness such as: laptop bodies, tripod legs, tent poles, fishing rods, hockey sticks, bows and arrows, racquet frames, stringed instrument bodies, drum shells, golf clubs, crash helmets and billiards cues.

The material is also referred to as graphite-reinforced polymer or graphite fiber-reinforced polymer (GFRP is less common, as it clashes with glass-(fiber)-reinforced polymer). In product advertisements, it is sometimes referred to simply as graphite fiber for short.

Few of the areas where carbon fiber can be used in our project is in the manufacturing of frame, swingarm and forks.

Methods of using carbon fiber:

Molding

One method of producing graphite-epoxy parts is by layering sheets of carbon fiber cloth into a mold in the shape of the final product. The alignment and weave of the cloth fibers is chosen to optimize the strength and stiffness properties of the resulting material. The mold is then filled with epoxy and is heated or air-cured. The resulting part is very corrosion-resistant, stiff, and strong for its weight. Parts used in less critical areas are manufactured by draping cloth over a mold, with epoxy either preimpregnated into the fibers (also known as pre-preg) or "painted" over it. High-performance parts using single molds are often vacuum-bagged and/or autoclave-cured, because even small air bubbles in the material will reduce strength. An alternative to the autoclave method is to use internal pressure via inflatable air bladders or EPS foam inside the non-cured laid-up carbon fiber.


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Vacuum bagging:

For simple pieces of which relatively few copies are needed (1–2 per day), a vacuum bag can be used. A fiberglass, carbon fiber or aluminum mold is polished and waxed, and has a release agent applied before the fabric and resin are applied, and the vacuum is pulled and set aside to allow the piece to cure (harden). There are two ways to apply the resin to the fabric in a vacuum mold.

The first method is manual and called a wet layup, where the two-part resin is mixed and applied before being laid in the mold and placed in the bag. The other one is done by infusion, where the dry fabric and mold are placed inside the bag while the vacuum pulls the resin through a small tube into the bag, then through a tube with holes or something similar to evenly spread the resin throughout the fabric. Wire loom works perfectly for a tube that requires holes inside the bag. Both of these methods of applying resin require hand work to spread the resin evenly for a glossy finish with very small pin-holes.

A third method of constructing composite materials is known as a dry layup. Here, the carbon fiber material is already impregnated with resin (pre-preg) and is applied to the mold in a similar fashion to adhesive film. The assembly is then placed in a vacuum to cure. The dry layup method has the least amount of resin waste and can achieve lighter constructions than wet layup. Also, because larger amounts of resin are more difficult to bleed out with wet layup methods, pre-preg parts generally have fewer pinholes. Pinhole elimination with minimal resin amounts generally requires the use of autoclave pressures to purge the residual gases out.

Compression molding:

Quicker method uses a compression mold. This is a two-piece (male and female) mold usually made out of fiberglass or aluminum that is bolted together with the fabric and resin between the two. The benefit is that, once it is bolted together, it is relatively clean and can be moved around or stored without a vacuum until after curing. However, the molds require a lot of material to hold together through many uses under that pressure.

Filament winding

For difficult or convoluted shapes, a filament winder can be used to make CFRP parts by winding filaments around a mandrel or a core.


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PHOTOGRAPHS DURING MANUFACTURING PROCESS

Photo 1: Cutting the sheet metal for the frame

Photo 2: One half of the frame


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Photos 3 and 4: Bending the sheet metal for the top part of the frame


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Photos 5 to 8: Fixing the two frame plates and the front fork


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Photo 9: Complete assembly of the swing arm


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Photo 10: Final assembly of the prototype


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CONCLUSION

The journey from the conception of this to project to the realization of the prototype has been a fruitful and learning process. It not only tested our academic skills, but also qualities of leadership, team work, financial management, and optimal utilization of time.

Although our prototype projects certain lacunae, we are proud of our achievement, given the fact that we were not working with extremely sophisticated equipment. The drawbacks may be attributed to a certain lack of specific knowledge or skill set, scarce availability of testing equipment, delays in procurement and manufacturing, and the most important factor, financial limitation.

We are thankful to all those who were involved in making this project a success, and we hope that projects such as ours or similar to ours, gain more and more momentum amongst industrial giants, and help revolutionalize the field of solo transportation, thus achieving the goal of environmentally friendly and technically unique means of transport.


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FINAL RENDERING OF THE BICYCLE ASSEMBLY


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BIBLIOGRAPHY OF REFERENCES

1. Literature reviews/ papers:

1.1. Bicycle and motorcycle balance and steer dynamics, by Jim Papadoupolos (Assistant Professor, Northern Illinois University), and Andy Ruina (Cornell University)

1.2. Forces in bicycle pedaling, by Jim Papadoupolos, PhD1.3. The long- distance bicycle, article from Bike Tech Magazine, by Chris Kostman1.4. Bicycle dynamics, by Jim Papadoupolos, PhD1.5. Measuring dynamic loads on a foldable city bicycle, from the University of

Ljubljana, Slovenia1.6. The Innovative Design of Quick Folding Bicycle with High Rigidity, by Hsieh,

Long-Chang; Chen, Tzu-Hsia1.7. Material Properties and Design Aspects of Folding Bicycle Frame, by M.S.J.

Hashmi, S. Mridha and S. Naher1.8. Characterizing and modeling of foldable cycle in Nanjing, China, by Yi Qi1.9. Using concept sketches to track design process, by P.A. Rodgers and A.

McGown1.10. Foldable bicycle; evaluation of current designs and novel design proposals, by

Arunachalam M., Rajesh R., and Arun Prakash R1.11. Engineering design process, by Yousef Haik, 2009

2. Websites:

2.1. www.bsahercules.com2.2. http://www.fietsberaad.nl/library/repository/bestanden/121107_Schwab_bicycling-safety-

and-the-lateral-stability-of-the-bicycle.pdf2.3. www.eurolines.co.uk/ documents /conditionsofcarriage.pdf 2.4. www.velobility.net/fileadmin/bilder/ Paper _ Bicycle / paper _ bicycle _EN.pdf 2.5. http://cozybeehive.blogspot.in/2008/11/design-case-study-innovation-of.html2.6. http://www.real-world-physics-problems.com/bicycle-physics.html 2.7. Bicycle power calculator,

http://www.mne.psu.edu/lamancusa/proddiss/bicycle/bikecalc1.htm2.8. Ultra cycling blog, http://www.blog.ultracycle.net/2010/05/cycling-power-

calculations2.9. www.goldenmotor.com2.10. www.netcomposites.com 2.11. www.azom.com


http://www.azom.com/

http://www.netcomposites.com/

http://www.goldenmotor.com/

http://www.blog.ultracycle.net/2010/05/cycling-power-calculations

http://www.blog.ultracycle.net/2010/05/cycling-power-calculations

http://www.mne.psu.edu/lamancusa/proddiss/bicycle/bikecalc1.htm

http://www.real-world-physics-problems.com/bicycle-physics.html

http://cozybeehive.blogspot.in/2008/11/design-case-study-innovation-of.html

http://www.velobility.net/fileadmin/bilder/Paper_Bicycle/paper_bicycle_EN.pdf

http://www.eurolines.co.uk/documents/conditionsofcarriage.pdf

http://www.fietsberaad.nl/library/repository/bestanden/121107_Schwab_bicycling-safety-and-the-lateral-stability-of-the-bicycle.pdf

http://www.fietsberaad.nl/library/repository/bestanden/121107_Schwab_bicycling-safety-and-the-lateral-stability-of-the-bicycle.pdf

http://www.bsahercules.com/

edited be report.docx

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