IvanoviSALEDamageModel modification to read plasticStrainRate

[YT610]

Dear Spheral,
Refer to the JohnsonCookDamage, JohnsonCookDamagePolicy and JohnsonCookFailureStrainPolicy, I want to make IvanoviSALEDamageModel to be plasticStrainRate dependent.
I simply added the following to the IvanoviSALEDamagePolicy

const auto psrKey = State::buildFieldKey(SolidFieldNames::plasticStrainRate, nodeListKey);
CHECK(derivs.registered(psrKey));
const auto& plasticStrainRate = derivs.field(psrKey, 0.0);

But it seems impossible to read plasticStrainRate, and always return the default value 0.0. Is it necessary to add other parameters?