basics of mechanical engineering designweb.mit.edu/2.00b/www/lectures/2017_lecture11.pdf · bolt...

Engineering Design

Basicsof Mechanical

Blade Boxes As you leave class today, look at all the boxesList your 3 favorite designs on ballot

LogisticsSketch Model Expo!

Informal, but prepared4 sketch models

Play testing at the Boston Children’s Museum Friday 6:30–8:30PM

feedback: receiving, relaying

Prepare! Prepare because:

1. You will know what you’re looking for

2. You don’t know what people will ask

3. Reviewers are here to help

Structure will help you distill feedback for most pertinent and meaningful

information

Credibility

To be persuasive we must be believable;to be believable we must be credible;to be credible we must be truthful.

—Edward R. Murrow

Popular Mistakes Game!silicone vs. silicon

silicon is an element that makes up sand and is used to make semiconductor wafers

silicone is a manmade rubber-like polymer

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

electric motors convert electricity into mechanical motion

engines produce kinetic energy from a fuel source

a nut is a threaded fastener used with a bolt

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

nut vs. washer

a washer is a ring with a hole used for distributing a load and sometimes spacing

silicone vs. silicon

engine vs. motor

nut vs. washer

bolt vs. screw

screws are shafts, typically tapered, with a helical groove or thread formed on its surface

bolts are externally threaded fasteners designed for insertion through holes tightened with a nut.

Popular Mistakes Game!requires a

through hole or a tapped

hole

requires a pilot hole

there are many metals which are basic elements

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

nut vs. washer

bolt vs. screw

metal vs. steel

steel is a metal alloy of iron and carbon

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

nut vs. washer

bolt vs. screw

metal vs. steel

tap vs. die

a die is a tool used to cut threads on a shaft

a tap is a tool used to cut threads in a hole

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

nut vs. washer

bolt vs. screw

metal vs. steel

tap vs. die

stiff vs. strong vs. tough

strength refers to materials ability to withstand load without failure

stiffness how a material deforms when loaded

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

nut vs. washer

bolt vs. screw

metal vs. steel

tap vs. die

stiff vs. strong vs. tough

strength refers to materials ability to withstand load without failure

toughness is the amount of energy per volume before failure, or resistance to fracture

stiffness how a material deforms when loaded

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

nut vs. washer

bolt vs. screw

metal vs. steel

tap vs. die

stiff vs. strong vs. tough

milling and turning

milling is like drilling but can cut in the sideways directions too

turning is machining cylindrical parts on a lathe

Popular Mistakes Game!silicone vs. silicon

engine vs. motor

nut vs. washer

bolt vs. screw

metal vs. steel

tap vs. die

stiff vs. strong vs. tough

milling and turning

chamfer vs. fillet vs. roundfillet is the rounding of an interior edge

chamfer is a beveled edge connecting two surfaces

round is the rounding of an exterior edge

Estimation!

Estimation!

Estimation!is a super important thing!

Quiz!What is your name?

What is energy? Units?

What is power? Units?

What are the top three sources of electricity in the USA?

Energya measure of the potential for change

never created or destroyed

converted between different forms!

Joules!

J = N⋅m = kg m2/s2

10 kg, 1 m

per day

Energy Range

10 MJ1kJ 100 MJ100 J 100 kJ10 kJ 1 MJ

1 Gallon 1.5 ton car

D Cell

AA Cell

sunflower seed

kJ = Thousand JMJ= Million J

PowerRate

Amount of work or energy transfer per unit time

Units of Watts or J/s

1 horsepower = 746 W =x 850

nascar engine = 634 kW

Power Range

1 MW100W 10 MW1 W 10 kW1 kW 100 kW

kW = Thousand WMW= Million W

MIT Building 39

TOYS

sinks

30 MJ / kg.05$ / kg

Energy for Electricity?

other

hydro 7%

nuclear 20%

gas 27%

coal 39%

USA energy production, 2015

How many Prudential Centers fit lying down across the Harvard bridge?

What is the cost per popcorn kernel at the movie theatre?

In the ToothTunes tooth brush how much should the battery pack weigh?

Can you power a mechanical bull in your house on a standard wall outlet?

How long will it take to heat a hot dog with an Easy Bake Oven?

Team Estimation Game

Game show!

Sketch Model Expodoes this sketch model explain more than the poster?

is it obvious that something was learned from making this model?

what’s the play?

is it fun?

Vote on Blade boxes