MAT E 202 EXAM QUESTIONS WELL ANSWERED LATEST UPDATE 2026
metals & alloys - Answers strong, ductile, moderate elasticity, 1-3 valence e-, sea of e-, non-
directional bond
ceramics & glasses - covalent - Answers strong, brittle, high elasticity, poor conductivity, sharing of
valence e-, directional bond, electronegativity
ceramics & glasses - ionic - Answers strong, hard, brittle, high elasticity, between cation & anion,
requires e- transfer, non-directional bond
polymers - intrachain bonding - Answers covalent
polymers - interchain bonding - Answers weak van der Waals forces
types of stress - Answers tensile, compressive, shear
Bauschinger Effect - Answers mechanical properties cannot be assumed equal under loading
elastic deformation (non-permanent) - Answers material will return to original shape on unloading
modulus of elasticity - Answers slope of elastic region, tangent to force curve at r0, inversely
proportional to CTE
microstructure (atomic) - Answers bonding between 2 atoms
microstructure (local) - Answers unit cell
microstructure (groups) - Answers crystalline/amorphous
covalent bond energy - Answers can be weak or strong
ionic bond energy - Answers high
metallic bond energy - Answers range
secondary bond energy - Answers weak
r0 - Answers equilibrium separation of atom centres at 0K, energy state where attractive / repulsive
forces are equal
E0 - Answers bond energy, energy required to separate 2 atoms an infinite distance from each other,
proportionate to melting temp.
plastic deformation (permanent) - Answers material doesn't return to original shape on unloading
yield stress - Answers stress at which plastic deformation begins
proportional limit - Answers idealized transition between elastic & plastic deformation
0.2% offset method - Answers standardized method to determine yield stress
ultimate tensile strength - Answers max. stress, where necking starts
ductility - Answers ability of a material to undergo plastic deformation
hardness - Answers measure of a material's resistance to plastic deformation (ceramics), 3UTS
rockwell hardness test - Answers measure depth of indentation made by cone (hard) or sphere (soft)
vickers hardness test - Answers dimensions of indentation are measured
brinell hardness test - Answers diameter of indentation is measured
catastrophic failure - Answers occurs instantly
fatigue - Answers occurs over a period of time
creep - Answers failure at high temperatures
macro level of failure - Answers one piece becomes two
micro level of failure - Answers breaking of bonds
brittle fracture - Answers bonds break suddenly, flat fracture surface (ceramics)
ductile fracture - Answers doesn't fail suddenly, energy absorbed in PD before failure, surface is
cup/cone (macro), dimples (micro) (metals)
griffith theory - Answers existing crack will propogate when the energy available is equal to the
energy required to form two new surfaces
toughness - Answers resistance to fracture, ability to absorb energy through PD (metals)
tensile toughness - Answers area under stress-strain curve, increases with area
plain strain fracture toughness - Answers measure of a material's resistance to fracture in the
presence of a flaw
factors affecting PD - Answers strain rate (inverse), temp. (proportional), state of stress
impact testing - Answers determine material's resistance to brittle fracture
charpy impact test - Answers notched sample, tested at high & low temp, loaded rapidly, energy
absorbed measured
ductile to brittle transition temperature - Answers temperature where sample absorbs less than 20J
of energy (average between upper & lower shelf energies), fracture appearance is 50% fibrous,
ensures materials are used at appropriate temperature
metals & alloys - Answers strong, ductile, moderate elasticity, 1-3 valence e-, sea of e-, non-
directional bond
ceramics & glasses - covalent - Answers strong, brittle, high elasticity, poor conductivity, sharing of
valence e-, directional bond, electronegativity
ceramics & glasses - ionic - Answers strong, hard, brittle, high elasticity, between cation & anion,
requires e- transfer, non-directional bond
polymers - intrachain bonding - Answers covalent
polymers - interchain bonding - Answers weak van der Waals forces
types of stress - Answers tensile, compressive, shear
Bauschinger Effect - Answers mechanical properties cannot be assumed equal under loading
elastic deformation (non-permanent) - Answers material will return to original shape on unloading
modulus of elasticity - Answers slope of elastic region, tangent to force curve at r0, inversely
proportional to CTE
microstructure (atomic) - Answers bonding between 2 atoms
microstructure (local) - Answers unit cell
microstructure (groups) - Answers crystalline/amorphous
covalent bond energy - Answers can be weak or strong
ionic bond energy - Answers high
metallic bond energy - Answers range
secondary bond energy - Answers weak
r0 - Answers equilibrium separation of atom centres at 0K, energy state where attractive / repulsive
forces are equal
E0 - Answers bond energy, energy required to separate 2 atoms an infinite distance from each other,
proportionate to melting temp.
plastic deformation (permanent) - Answers material doesn't return to original shape on unloading
yield stress - Answers stress at which plastic deformation begins
proportional limit - Answers idealized transition between elastic & plastic deformation
0.2% offset method - Answers standardized method to determine yield stress
ultimate tensile strength - Answers max. stress, where necking starts
ductility - Answers ability of a material to undergo plastic deformation
hardness - Answers measure of a material's resistance to plastic deformation (ceramics), 3UTS
rockwell hardness test - Answers measure depth of indentation made by cone (hard) or sphere (soft)
vickers hardness test - Answers dimensions of indentation are measured
brinell hardness test - Answers diameter of indentation is measured
catastrophic failure - Answers occurs instantly
fatigue - Answers occurs over a period of time
creep - Answers failure at high temperatures
macro level of failure - Answers one piece becomes two
micro level of failure - Answers breaking of bonds
brittle fracture - Answers bonds break suddenly, flat fracture surface (ceramics)
ductile fracture - Answers doesn't fail suddenly, energy absorbed in PD before failure, surface is
cup/cone (macro), dimples (micro) (metals)
griffith theory - Answers existing crack will propogate when the energy available is equal to the
energy required to form two new surfaces
toughness - Answers resistance to fracture, ability to absorb energy through PD (metals)
tensile toughness - Answers area under stress-strain curve, increases with area
plain strain fracture toughness - Answers measure of a material's resistance to fracture in the
presence of a flaw
factors affecting PD - Answers strain rate (inverse), temp. (proportional), state of stress
impact testing - Answers determine material's resistance to brittle fracture
charpy impact test - Answers notched sample, tested at high & low temp, loaded rapidly, energy
absorbed measured
ductile to brittle transition temperature - Answers temperature where sample absorbs less than 20J
of energy (average between upper & lower shelf energies), fracture appearance is 50% fibrous,
ensures materials are used at appropriate temperature
