Hi Siddharth,
Please note that the meshing algorithm works differently for different physics. So, the EM mesh generated by HFSS would not help your case for static structural analysis in Workbench.
Yes, it is possible to do mechanical stress analysis in the AEDT. Please go through the AEDT Mechanical help document and structural solution - power resistor getting started guide for detailed information.
Best regards,
Praneeth.