Hello,
You can change Young modulus during calculation.
The modulus can be set respect to field dependecies and value of field variable
can be control respect to analysis time with *FIELD keyword or if necessary control with a subroutine.
Search for "field variable" on the forum and also check Abaqus documentation:
Abaqus Analysis User's Manual, Part VII: Prescribed Conditions, 32.6.1 Predefined fields
If you need detail information please let me know.
Regards,
Bartosz