To put it simpler: a flat thin rectangular body is rotating around one axis perpendicular to its large face. There are no other degrees of freedom. in a transient structural simulation TEMP is undefined. When I enable structural thermal via "et,matid,226,11" APDL command, and start to rotate the body, the result is that its temperature drops. Increasing number of time steps helps to keep the temperature closer to its initial value but then the number of time steps required for this is massive. It appears to make no sense to me from physics or numerical point of view. Advice would be appreciated. Many thanks.