Mechanical properties Flashcards
What is Yield strength
O’ y
Stress at which noticeable plastic deformation has occurred
What is Ultimate Tensile Strength (UTS)
Maximum stress on engineering stress-strain curve
What is ductility
Measure of the degree of plastic deformation that has been sustained at fracture
What is toughness
Ability to absorb energy and plastically deform before fracturing
What is resilience
Ability to store energy (elastic region)
What is hardness
Measure of resistance to surface plastic deformation (dent, scratch)
What is factor of safety
A coefficient applied to calculated stress to account for imperfections/ slips, returning design stress
Write the expression for Engineering tensile stress
O’ = Ft / Ao
Ft : force tensile (N)
Ao: original area (m^2)
Write the expression for Eng shear stress
T = Fs/ Ao
Fs = force shear (N)
Ao = original area (m^2)
Expression for Eng tensile strain
E = o’ / Lo
E = epsilon
o’ = stress (N/m^2)
Lo = original length
Expression for Eng shear strain
Y = delta X / y = tan (theta)
Expression for Hooke’s law
o’ = E * e
Stress = modulus of elasticity * strain
Expression for Modulus of elasticity in terms of interatomic force or potential energy
E <x (dF/ dr)
E is proportional to the slope of Force / seperation at equilibrium
Expression for poisson’s ratio
V = - Ex / Ez
Ex = delta diameter/ original diameter
Ez = delta length / og length
Expression for measurement of ductility
%EL = (Lf-Lo)/Lo *100 %
%RA = (Ao - Af)/Ao *100%
