measurement of evolution of damage variable

Hi All,

I want to use ductile damage model in ABAQUS to model the damage of thermoplastic polymers, in which I need to input the damage evolution law (\dot{d}).

My question is on the way we have to measure the variable d.

Suppose I have 10 cycles of load-unload test. For slope of the first load will be initial Young's modulus at undamaged state E_0. now for the next cycle, which part of the curve we need to measure their slope to get the damage variable (d = 1 - E/E_0).