PKG 221 EXAMS SCRIPT UPDATED QUESTIONS AND
ANSWERS GRADED A+
✔✔ceramics - ✔✔glass, brick, concrete
✔✔plastics - ✔✔polyethylene, pp, rubber, wood
✔✔stiffness - ✔✔measure of how easily it will stretch/ bend
✔✔toughness - ✔✔mesure of how much energy a material can absorb without breaking
✔✔ductile - ✔✔metal and plastic can stretch a lot before rupture
✔✔brittle - ✔✔glass breaks easily
✔✔permeability - ✔✔measure of how easily gases move through barrier
✔✔alloying - ✔✔adding elements
✔✔cold working - ✔✔deform at room temperature
forging
drawing
✔✔annealing - ✔✔heat to soften, reverse of cold work, relieve stress
✔✔quenching - ✔✔opposite of annealing (fast cooling)
✔✔cross sectional area - ✔✔area of cross section piece of material
✔✔stress - ✔✔force/ csa unit: psi
✔✔strain - ✔✔change in L/ original L
✔✔modulus of elasticity - ✔✔stress at PL/ Strain at PL
✔✔percent neckdown - ✔✔change in width @PL/ original W*100
✔✔Atmospheric pressure - ✔✔weight of a column of air from sea level to the top of the
atmosphere
✔✔1 atm - ✔✔14.7 psi measured with manometer
✔✔axial stress - ✔✔in direction of axis (up and down)
, ✔✔hoop stress - ✔✔around the can
✔✔pressurized can Compression strength - ✔✔empty can CS + gas pressure X area of
the top
✔✔Stress Concentration - ✔✔small defects are stress concentrators (cracks, scratches)
forces stress into small area and raises stress
✔✔factors affecting stress test - ✔✔temperature and test rate
✔✔creep - ✔✔deflecting under constant laod over time
✔✔stress retentnion - ✔✔final stress/ initial stress * 100%
✔✔thermal expansion - ✔✔expand and contract due to temperature
proportional to temp change
✔✔strain - ✔✔expansion coeff * temperature change
✔✔Viscoplasticity - ✔✔material property where the deformation under load is rate
dependant (how fast the force applied)
demonstrates both viscous
✔✔thermal stress - ✔✔a material may be restrained from expanding or contracting by
intself rather than some external agent
✔✔restraining stress - ✔✔MOE * expansion coeff. * temperature change
✔✔4 factors that control tension produced - ✔✔MOE
wall thickness
absolute temp difference
ration of surface coeff and the internal thermal conductivity
✔✔New length - ✔✔old L + (old L x coeff x temp change)
✔✔Friction - ✔✔force resisting relative motion
necessary for packaging
✔✔Static Friction - ✔✔minimum angle for block to start moving
✔✔Kinetic Friction - ✔✔minimum angle for block to keep moving once it has started
✔✔force to start the blocksliding - ✔✔P= us(W)
ANSWERS GRADED A+
✔✔ceramics - ✔✔glass, brick, concrete
✔✔plastics - ✔✔polyethylene, pp, rubber, wood
✔✔stiffness - ✔✔measure of how easily it will stretch/ bend
✔✔toughness - ✔✔mesure of how much energy a material can absorb without breaking
✔✔ductile - ✔✔metal and plastic can stretch a lot before rupture
✔✔brittle - ✔✔glass breaks easily
✔✔permeability - ✔✔measure of how easily gases move through barrier
✔✔alloying - ✔✔adding elements
✔✔cold working - ✔✔deform at room temperature
forging
drawing
✔✔annealing - ✔✔heat to soften, reverse of cold work, relieve stress
✔✔quenching - ✔✔opposite of annealing (fast cooling)
✔✔cross sectional area - ✔✔area of cross section piece of material
✔✔stress - ✔✔force/ csa unit: psi
✔✔strain - ✔✔change in L/ original L
✔✔modulus of elasticity - ✔✔stress at PL/ Strain at PL
✔✔percent neckdown - ✔✔change in width @PL/ original W*100
✔✔Atmospheric pressure - ✔✔weight of a column of air from sea level to the top of the
atmosphere
✔✔1 atm - ✔✔14.7 psi measured with manometer
✔✔axial stress - ✔✔in direction of axis (up and down)
, ✔✔hoop stress - ✔✔around the can
✔✔pressurized can Compression strength - ✔✔empty can CS + gas pressure X area of
the top
✔✔Stress Concentration - ✔✔small defects are stress concentrators (cracks, scratches)
forces stress into small area and raises stress
✔✔factors affecting stress test - ✔✔temperature and test rate
✔✔creep - ✔✔deflecting under constant laod over time
✔✔stress retentnion - ✔✔final stress/ initial stress * 100%
✔✔thermal expansion - ✔✔expand and contract due to temperature
proportional to temp change
✔✔strain - ✔✔expansion coeff * temperature change
✔✔Viscoplasticity - ✔✔material property where the deformation under load is rate
dependant (how fast the force applied)
demonstrates both viscous
✔✔thermal stress - ✔✔a material may be restrained from expanding or contracting by
intself rather than some external agent
✔✔restraining stress - ✔✔MOE * expansion coeff. * temperature change
✔✔4 factors that control tension produced - ✔✔MOE
wall thickness
absolute temp difference
ration of surface coeff and the internal thermal conductivity
✔✔New length - ✔✔old L + (old L x coeff x temp change)
✔✔Friction - ✔✔force resisting relative motion
necessary for packaging
✔✔Static Friction - ✔✔minimum angle for block to start moving
✔✔Kinetic Friction - ✔✔minimum angle for block to keep moving once it has started
✔✔force to start the blocksliding - ✔✔P= us(W)
