Sheet Metal Forming

Abbreviations and Symbols / xiii
ε
e,o
elastic limit 
ε
o
initial strain
ε
pl
plastic strain
ε
r
strain in radial direction
ε
t
total strain, strain in thickness 
direction, strain in tangential 
direction
ε
w
width strain
ε
z
strain in axial direction
ε
0
prestrain
ε
θ
strain in the hoop direction
ε
φ
strain in the longitudinal 
direction
ε
equivalent strain, effective strain
ε
p
plastic strain
·
ε
equivalent strain rate, effective 
strain rate, von Mises equivalent 
plastic strain
η
lubricant viscosity, deformation 
efficiency, efficiency factor 
θ 
bending angle, punch angle, 
crankshaft rotation, temperature 
θ' 
final bend angle
θ
p 
half bending angle
θ
s
springback angle
θ
1
half angle (under load)
θ
2
half angle (unloaded)
θθ 
hoop stress
θφ 
axial stress
∆θ
springback angle
κ
bulk modulus
λ
hole expansion ratio, roughness 
parameter
µ
coefficient of friction 
µ
m
mean coefficient of friction
ν
Poisson’s ratio
ρ
e
elastic radius of curvature
ρ
0
radius of curvature
σ
stress, flow stress, true normal 
stress
σ
b
yield stress in balanced biaxial 
state
σ
CY
compressive yield strength
σ
e
engineering stress
σ
f
flow stress
σ
m
stress quantity, mean stress
σ
n
normal stress
σ
oc
compression yield stress
σ
r
rupture stress, stress in radial 
direction
σ
t
stress in tangential direction
σ
UTS
ultimate tensile strength
σ
Y
yield strength
σ
z
longitudinal stress, stress in axial 
direction
σ
0
initial yield stress
σ
hoop stress
σ
flow stress, instantaneous yield 
stress
τ
shear stress, frictional shear 
stress
τ
a
average shear stress at contacting 
asperity peaks
τ
b
average shear stress at lubricant 
pockets
τ
f
,
 
τ
f
frictional shear stress
τ
s
shear stress
φ
bend angle, logarithmic strain
ω
angular speed or velocity
2-D 
two-dimensional
3-D 
three-dimensional

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Sheet Metal Forming—Processes and Applications 
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T. Altan and A.E. Tekkaya, editors 
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