equivalent plastic strain
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![Page 1: Equivalent Plastic Strain](https://reader036.vdocuments.us/reader036/viewer/2022081820/546961aeaf795922598b4765/html5/thumbnails/1.jpg)
Effective plastic strain rate:
( ) ( ) ( ) ( ) ( ) ( )[ ]{ } 2/12222222
3
2
3
2 pyz
pxz
pxy
pzz
pyy
pxx
pij
pij
p εεεεεεεεε &&&&&&&&& +++++==
Effective plastic strain:
∫= dtpp εε &
For example uniaxial tension in the x-direction the strain rates are
0
0
0
5.0
5.0
=
=
=
−=
−=
=
pyz
pxz
pxy
pzz
pyy
pxx
εε
εεε
εεεε
&
&
&
&&
&&
&&
Where the -0.5 factors are from conservation of volume (“Plastic Poisson’s Ratio” = 0.5). The effective plastic strain rate is
( ) ( ) ( ){ } ( ) εεεεεε &&&&&& ==−+−+= 22/1222
2
3
3
25.05.0
3
2p
So that for uniaxial loading the effective plastic strain rate is equal to the strain rate in the
loading direction (this is the point of the 3/2 factor). This is similar conceptually to effective stress.