Mechanical Properties: Review

1
Mechanical Properties Review
nominal (engineering)
true
F
stress
strain
l0
elastic stretch chemical bonds
sy
plastic rearrange chemical bonds
s (stress)
Y
e (strain)
2
Shear stress from uniaxial tension
force is normal to the plane
normal stress
F
consider what happens on some other plane, A
A
need to know area of A'
A' A/cos(f)
f
q
F'
consider shear force parallel to A'
strain
A'
need to know magnitude of F'
elastic stretch chemical bonds
F' Fcos(q)
F' can be along any direction parallel to A'
(each corresponds to a different q)
Final result tmax s/2, in the orientation f
q p/4
plastic rearrange chemical bonds
s (stress)
Y
e (strain)
3
Solute Hardening
4
Precipitate Hardening
incoherent
coherent