Nonlinear finite elements/Homework 11/Solutions/Problem 1/Part 1

Problem 1: Part 1: Evolution rule for plastic flowEdit

Let   be the equivalent plastic strain, defined as

 

Express the time derivative of   in terms of   and  . This is the evolution law for  .

The time derivative of   is given by

 

Now,

 

Therefore,

 

Using

 

we get