BYMUKUL KASHIWAL

PRESENTATIONON

BAJA VEHICLE CHASIS DESIGN

CATIA INTRODUCTION CATIA (Computer Aided Three-dimensioning Interactive

Application) is a computer aided design tool programmed in C++ language by Dassault Systems and marketed by IBM.

CATIA is the world’s leading CAD/CAM/CAE software.

It is also called as 3D ‘Product Lifecycle Management’ software because it is also used at various industrial levels from design process to manufacturing level of various products.

CATIA offers a solution to shape design, styling, surfacing workflow and visualization to create modify, and validate complex innovative shapes .

BAJA

Baja SAE is an intercollegiate design competition run by the Society of Automotive Engineers (SAE).

The goal in Baja SAE racing is to design, build and race off-road vehicles.

Baja is sponsored by “Mahindra & Mahindra Limited”.

CHASSIS

Roll Cage can be called as skeleton of a vehicle, its main purpose is to form a frame or so called Chassis.

Types of Chassis

LADDER FRAME CHASSIS TUBULAR SPACE FRAME CHASSIS MONOCOQUE FRAME CHASSIS ULSAB MONOCOQUE BACKBONE FRAME CHASSIS ALUMINIUM SPACE FRAME CARBON-FIBBER MONOCOQUE

LADDER FRAME CHASSIS

Advantages- The following are the advantages - it is easy cheap for hand build Proves good for SUVs.

Disadvantages- Torsional rigidity is very much lower especially when dealing

with vertical load or bumps.

Who use it ?It is used by Most SUVs, classic cars, Lincoln Town Car, Ford,

Crown Victoria etc.

TUBULAR SPACE FRAME CHASSIS

3 dimensional design high-end sports cars adopt tubular space frame to enhance the

rigidity / weight ratio tubes are welded together and forms a very complex structure

Advantages- Very strong in any direction. (compare with ladder chassis and

monocoque chassis of the same weight) Disadvantages- Very complex. Costly and time consuming to be built. Impossible for robotised production. Besides, it engages a lot of space, Raise the door sill and result in difficult access to the cabin.

Who use it ?It was used by all Ferrari before the 360M, Lamborghini Diablo,

Jaguar XJ220, Cater ham, TVR etc.

MONOCOQUE FRAME CHASSIS

Monocoque is a one-piece structure which defines the overall shape of the car.

The floor pan, which is the largest piece, and other pieces are press-made by big stamping machines.

Chassis is actually made by spot welding several pieces together.

Advantages- Cheap for mass production. Inherently good crash protection. Space efficient. Disadvantages- Heavy. Impossible for small-volume production.

Who use it ? Nearly all mass production cars, all current Porsche

ULSAB MONOCOQUE

Ultra Light Steel Auto Body (ULSAB) It has the same structure as a conventional monocoque It differs from its donor is in minor details - the use of "Hydro-form" parts

Advantages- Stronger and lighter than conventional monocoque without increasing

production cost.

Disadvantages- Still not strong or light enough for the best sports

cars.

Who use it ? Opel Astra, BMW 3-series.

BACKBONE FRAME CHASSIS

It's strong enough for smaller sports cars but not up to the job for high-end ones.

A strong tubular backbone (usually in rectangular section) connects the front and rear axle and provides nearly all the mechanical strength.

Advantages- Strong enough for smaller sports cars. Easy to be made by hand thus cheap for low-volume

production. Simple structure benefit cost.

Disadvantages- Not strong enough for high-end sports cars.

The backbone does not provide protection against side impact or off-set crash.

Therefore it needed other compensation means in the body. Cost ineffective for mass production.

Who use it ? Lotus Esprit, Élan Mk II, TVR, Marcos.

ALUMINIUM SPACE FRAME

Consists of extruded aluminium sections, vacuum die cast Components and aluminium sheets of different thicknesses.

It's quite complex and production cost is far higher than steel monocoque.

 Advantages- Lighter than steel monocoque. As space efficient as it.

Disadvantages- Still expensive for mass production.

Who use it ? Audi

CARBON-FIBBER MONOCOQUE

Most so-called "supercars" use carbon-fibber in body panels only.

Kelvar is the most common Carbon-fibre used in motor industry due to its highest rigidity-to-weight ratio.

Advantages- The lightest and stiffest chassis.

Disadvantages- By far the most expensive.

Who use it ? McLaren F1, Bugatti EB110SS, Ferrari F50.

Chassis Design Considerations Stiffness Weight Fitment and Packaging

Chassis Material Considerations Steel Aluminium

AISI 1018The chassis can be broken up into three plane structures and two

tubular sections that connect them. Starting from the front of the chassis and working back, these sections are-

Front Bulkhead

o It is “a planar structure that defines the forward plane of the Major Structure of the Frame”.

Front Roll Hoop

o It is “a roll bar located above the driver’s legs, in proximity to the steering wheel.”

Front Bulkhead Support System and Front Hoop Supports

Front hoop supportThis is the structure which connects the front hoop

and front bulkhead.

Front bulkhead support system

The bulkhead support system was made by incorporating the front suspension box in a support structure that supports the front hoop support, bulkhead and triangulated with the base rod

Main Hoop, Main Hoop Bracing

Side Impact Structure

Rear Suspension and Engine Housing

STRUCTURAL ANALYSIS

Vehicle loading Longitudinal Torsion Vertical Bending Lateral Bending Horizontal Lozenging

FINITE ELEMENT ANALYSIS After finalizing the frame along with its material and

cross section, it is very essential to test the rigidity and strength of the frame under severe conditions. The frame should be able to withstand the impact, torsion, roll over conditions and provide utmost safety to the driver without undergoing much deformation. Following tests were performed on the roll cage-

Front impact, Side impact, Rear impact, Roll Over

Front impact analysis Impact load calculation: Using the projected vehicle/driver mass of 325 kg,

the impact force was calculated base on a G-load of 10 for extremely worst condition.

F = ma …. (1) = 325*10*10 = 32500 N Impact Time= weight*(velocity/load)… (2) = 325*(16.67/36000) = 0.15 seconds.

Rear impact analysis Impact load calculation: Using the projected vehicle/driver mass of 325 kg,

the impact force was calculated base on a G-load of 10 for extremely worst condition.

F = ma …. (1) = 325*10*10 = 32500 N Impact Time= weight*(velocity/load)… (2) = 325*(16.67/36000) = 0.15 seconds

Side impact Analysis Impact load calculation: Using the projected vehicle/driver mass of 325 kg,

the impact force was calculated base on a G-load of 5 for extremely worst condition.

F = ma …. (1) = 325*5*10 =16250N

Roll Over Analysis Impact load calculation: Using the projected vehicle/driver mass of 325 kg,

the impact force was calculated base on a G-load of 2 for extremely worst condition.

F = ma …. (1) = 325*2*10 =6500N

APPLIED

FORCE

MAXIMUM

STRESS

(Von-Misses)

MAXIMUM

STRESS

(Principal

Stress)

MAXIMUM

DEFORMATION

FACTOR

OF

SAFETY

FRONT IMPACT

36000N 180MPa 149MPa 5.75mm 2.06

REARIMPACT

36000N 195MPa 128MPa 5.5mm 1.9

SIDE IMPACT

18000N 161MPa 156MPa 1.65mm 2.3

ROLL OVER

7400N 114MPa 68.17MPa 0.8mm 3.25

RESULTS

Thank You