Hello.

Can you suggest how to SfePy set the second time derivative (with existing term or with new).

The essence of the problem simple Mx (d2u/dt2) + Cx (du / dt) + Kxu = Q. This is a classical significance equation of motion mechanical system with damping.

All my attempts to hurriedly add the desired derivative unaesthetic or ineffectual.

Artem Sobolev.