Transcript lecture 16 powerpoint

Mechanical Properties: Review
nominal (engineering)
F
A0
stress
 FA
0
strain  
l  l0
l0
true
 FA
i
l
l 
dl
dl
d 
  total    ln  
l
l
 l0 
l
0
elastic – stretch chemical bonds
 (stress)
l0
y
plastic – rearrange chemical bonds
Y
 (strain)
Shear stress from uniaxial tension
normal stress
F
A
 FA
force is normal to the plane
consider what happens on some other plane, A’
need to know area of A′
A′ = A/cos(f)
f q
n̂
A′
F′
consider shear force parallel to A′
need to know magnitude of F′
F′ = Fcos(q)
F′ can be along any direction parallel to A′
(each corresponds to a different q)
Final result: tmax = /2, in the orientation f = q = p/4
Solute Hardening
Precipitate Hardening
coherent
incoherent