Basics of Mechanical Engineering Designweb.mit.edu/2.00b/www/lectures/2017_lecture11.pdf · bolt...
Transcript of 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