How can be the strain greater than unity?

[zhankeliu]

Does anyone know how can the plastic strain be greater than unity? Such as in the benchmark manual 3.2.10 Indentation of a crushable foam plate:

*CRUSHABLE FOAM HARDENING
0.2000E6, 0.0000
0.2577E6, 0.0094
0.2760E6, 0.0258
0.3053E6, 0.0452
0.3267E6, 0.0655
0.3623E6, 0.1084
0.3891E6, 0.1540
0.4250E6, 0.2405
0.4568E6, 0.3812
0.4738E6, 0.4600
0.5170E6, 0.6391
0.5862E6, 0.8570
0.6503E6, 0.9857
0.7470E6, 1.1324
0.9820E6, 1.2965
1.4702E6, 1.4808
2.7262E6, 1.6609
5.3911E6, 1.9000

 

[TGS4]

You seem to be under the impression that a plastic strain greater than 1 is somehow not allowed. Why? There's nothing magical about a strain of 1 (or unity as you called it). This material can simply handle a significant amount of deformation before reaching its ultimate stress.

 

[gurmeet2003]

Plastic strain is defined in terms of 'True' strain. This may explain why it can be greater than 1.

Gurmeet