Syllabus objectives Flashcards
what is a community problem that a mechanical engineer would solve?
Providing clean and accessible water to communities in need by designing and developing systems which can remove bacteria and impurities and water to provide clean and accessible water to everyone.
what is a community problem that a mechatronics engineer would solve?
improving emergency response through the development of robots and drones enabling autonomous navigation, obstacle avoidance, debris removal and delivery of supplies.
what is a community problem that a biomechanics engineer would solve?
they can develop advanced prosthetic limbs, orthotic devices ad mobility aids to improve the quality of life for individuals with limb loss or mobility impairments within the community.
what engineering understanding do biomechanical engineers need to develop prosthetic limbs for communities?
- structural analysis to ensure the prosthetic can withstand various loads and forces encountered during regular use.
- expertise in selecting materials that balance strength, durability, weight and biocompatibility
- metals, polymers and composites.
- understanding of biomechanics and anatomy to replicate natural movements.
what engineering understanding do mechatronics engineers need to develop emergency response robots and drones?
- control software for autonomous navigation
- understanding of materials like aluminium, steel, or composite materials to ensure strength, durability and lightweight construction
- understanding of sensor materials and technology
what engineering understanding do mechanical engineers need to develop water filtration systems for communities?
- understanding of technology and materials to ensure its functionality, durability and effectiveness
- understanding of materials such as PVC, stainless steel, non corrosive materials and abrasive resistant materials
how does a bicycle provide mechanical advantage?
its gear system allows the rider to convert a small input force into a larger output force. the longer pedal arms (cranks) are allow the rider to generate a greater torque on the crank, which translates into more power
how does a car jack provide mechanical advantage?
a car jack employs a screw thread for heavy lifting. A small force is applied in a horizontal plane and used to raise or lower a large load.
how does a crow bar provide mechanical advantage?
a crow bar is a class one lever as the effort force and applied force at at either end of the fulcrum. A crowbar provides mechanical advantage through leverage as the smaller effort distance translates to a larger load distance.
what is linear motion?
motion in a straight line in a horizontal or vertical direction
what is rotary motion?
motion in a continuously circular path that is about an axis
what is oscillatory motion?
repeated motion
what is reciprocal motion?
repetitive back and forth or up and down
what is mechanical advantage?
the ratio of the output force produced by a machine to the force applied to it
what is velocity ratio?
the ratio of distance moved by the effort to the distance moved by the load
what is the mechanical advantage of an inclined plane?
length/height
what is the total acting force on an inclined plane?
Ff + mgsin0
what is a first class lever?
fulcrum between the load and effort
what is a second class lever?
load between the fulcrum and effort
what is a third class lever?
effort between the fulcrum and the load
what is the VR of a spur gear?
no. teeth on driven/ no. teeth on the driver
what is the VR of a worm gear?
no. teeth on worm wheel/ no. of threads on worm
what is the VR of a rack and pinion?
no. of teeth on pinion x no. of teeth on the rack
what is the VR of a pulley?
number of ropes attached to a moving pulley
what is friction?
the force opposing motion
what is the angle of repose?
the steepest angle at which a sloping surface formed of loose material stable
what is the normal force?
component of a contact force that is perpendicular to the surface that an object contacts
what is the x axis of the stress strain curve?
strain
what is the y axis of the stress strain curve?
stress
how can you determine stiffness from the stress strain curve?
youngs modulus = rise/run= stiffness
what is stiffness?
the extent to which an object resists deformation in response to an applied force
what is toughness?
the ability of a material to absorb energy and plastically deform without fracturing
what is the proportional limit?
the highest stress point at which the material exhibits purely elastic behaviour while there is a proportional correlation between stress and strain
what is yield strength?
indicates the limit of elastic behaviour and the beginning of plastic behaviour
what is ultimate tensile strength?
the maximum stress that a material can withstand while being being stretched or pulled before breaking
how can you find toughness on a stress strain curve?
area under the curve
what is the behaviour of ceramics on a stress strain curve?
ceramics can withstand high levels of stress (stiffness) but small amounts of strain before breaking - brittle and strong but not ductile
what is the behaviour of mild steel on a stress strain curve?
portrays the usual curve can withstand a regular amount of stress and then enters the plastic region. has the largest area under the curve = tough and ductile
what is the behaviour of polymers on a stress strain curve?
can withstand only small amounts of stress (not stiff) and high levels of strain = most ductile material
what is the eutectic temperature on a lead tin thermal equilibrium phase diargam?
183 degrees celsius
what is the eutectic composition on a lead-tin thermal equilibrium phase diagram?
62% tin (Sn)
38% lead (Pb)
what are the 4 different microstructures as a 5% Sn composition cools on a lead-tin thermal equilibrium phase diagram?
- pure liquid austenite
- liquid austenite with bits of ferrite
- solid ferrite
- solid ferrite with bits of cementite
how do you find % weight solid?
distance from liquidus line to compositon/ distance from liquidus line to solidus line
how do you find % weight liquid?
distance from solidus line to compositon/ distance from solidus line to liquidus line
what is the total composition of C on an iron carbon phase diagram?
6.7%
what is the portion of steel on a n iron carbon phase diagram?
0 - 2% carbon
what is the portion of cast-iron on an iron carbon phase diagram?
2 - 6.7% carbon
what is the microstructure of hypo-eutectoid steel?
pearlite with bits of ferrite
what is the microstructure of hyper-eutectoid steel?
pearlite with cementite
what is the section of hypo eutectoid steel on an iron carbon phase diagram?
0 - 0.76% carbon
what is the section of hyper eutectoid steel on an iron carbon phase diagram?
0.76 - 2.14% carbon
what is the effect of decreasing carbon content on steel?
as carbon content is decreased, the amount of ferrite increases, increasing ductility and reducing strength
what is the effect of increasing carbon content on steel?
as carbon content is increased, the amount of cementite is increases, increasing strength and reducing ductility.
what is the % carbon of low carbon steel and what are its applications?
0.07-0.15% carbon
- automobile parts
- wire products
what is the % carbon of mild carbon steel and what are its applications?
0.15 - 0.3% carbon
- structural plates and sections
- stampings
- forgings
what is the % carbon of medium carbon steel and what are its applications?
0.3 - 0.6% carbon
- forgings
- automotive components
what is the % carbon of high carbon steel and what are its applications?
0.6 - 1.25% carbon
- cutting tools
- punches
- dies
- industrial knives
what is the % carbon of ultra high carbon steel and what are its applications?
1.25 - 2% carbon
- non industrial knives
- punches
- axles
what are the properties of low carbon steel?
- soft
- ductile
- tough
what are the properties of mild carbon steel?
- ductile
- weldable
- high tensile strength
what are the properties of medium carbon steel?
- strong
- wear resistant
- tough
what are the properties of high carbon steel?
- strong
- hard
- resistant
- less ductile
what are the properties of ultra-high carbon steel?
- strong
- hard
- brittle
what are the two eutectoid temperatures on an iron-carbon phase diagram?
1147 degrees celsius
723 degrees celsius
how does the microstructure of a 3% carbon cast iron change during cooling between the eutectoid temperatures?
when temp 1147 is reached the residual liquid forms the eutectic mixture of austenite and cementite along with austenite dendrites. as the temp drops to 723 carbon precipitates out of the austenite to be deposited as growing areas if eutectic cementite. when 723 is reached the remaining austenite changes to pearlite.
what are the uses of polyethylene?
- plastic containers
- water pipes
- cable insulation
what are the uses of polypropylene
- lab equipment
- electronics
- automobile products
what are the uses of acrylonitrile butadiene styrene?
- automotive body parts
- household electronics
- electrical appliances
what are the uses of polylactic acid?
- automobile interiors
- medical implants
what are the uses of polyvinyl chloride?
- automobile parts
- electronic and electrical equipment
- waste/water drainage pipe
what are the uses of nylon?
- gears
- rollers
- bearings
what is the truth table of a AND gate?
00=0
01=0
10=0
11=1
what is the truth table of a NAND gate?
00=1
01=1
10=1
11=0
what is the truth table of an OR gate?
00=0
01=1
10=1
11=1
what is the truth table of a NOR gate?
00=1
01=0
10=0
11=0
what is the truth table of an XOR gate?
00=0
01=1
10=1
11=0
what is the truth table of an XNOR gate?
00=1
01=0
10=0
11=1
describe a community problem related to a sustainability issue that engineers have developed a solution for?
- stoves in developing countries used biomass such as timber as fuel
- contributes to poor air quality
- engineers have used their knowledge of ‘high tech’ alloys and ceramics to develop low cost stove solutions
- they have improved burning efficiency, reduced size, and reduced smoke output
- improved air quality improving health and impact on global warming.
