Question

What do you understand by plastic strain increment in Elastic perfectly plastic material and explain its importance?

Answer 1

Elastic perfectly plastic material is that in which once yield stress occurs than it will deform plastically. For this type of material we assume that there is no work hardening and the material is perfectly plastic.

Plastic Strain Increment-

Plastic deformation is a path dependent process because of its dissipation characteristics.

When examining the plastic deformation we must work on increment in strain rather than total accumulated strain. The total strain can be obtained by summing up the increments.

The plastic strain increment is assumed to be proportional to the deviatoric stress and " Prandtl-Reuss equation" is used.

Importance of plastic deformation increment -

1. Specifies the onset of plastic deformation for different combination of applied load.

2. Prescribes the work hardening of the material and the change in the yield condition with the progression of plastic deformation.

3. Relates increment of plastic deformation to the stress components.