[sur4j]

I am trying to create a time and temperature dependant variable within the solidDisplacementFoam solver, currently the value is defined as a constant volScalarField as shown:
volScalarField mu("mu", E/(2.0*(1.0 + nu)));
I need this to change in the following way: When reaching a certain temperature it should start increasing at a constant rate in time up till reaching a final value at which it stops increasing. I attempted to do this by adding the following code into the main .C file:

forAll(mu.internalField(), cellI)
{
if(T.internalField()[cellI]>330){
 mu.internalField()[cellI] = 10e+06;
      }
}
mu.correctBoundaryConditions();

mu currently is set to a constant value upon reaching 330K temperature, how would I make this so that it increases at a constant rate in time and stops at a new larger value of mu when reaching the temperature?

Any help at all with this problem would be greatly appreciated. Thank you.