Ansys Learning Forum Forums Discuss Simulation General Mechanical Apply prestress with the inistate command, for a hyperelastic material (Yeoh) Reply To: Apply prestress with the inistate command, for a hyperelastic material (Yeoh)

peteroznewman
Subscriber

Hello Charlotte,

Yes, Inistate works for NLGEOM.

When a FEA model converges, the internal forces in all the elements are in equilibrium. In the first model, the internal forces include the gravity body force pulling the mass down, while tensile stress in the element on top and compressive stress in the elements on the bottom form an equilibrium with the gravity force.  The stresses are written into the ini file.

When you apply that state of stress to the horizontal mesh without gravity body forces, the internal forces created by the inistate stresses are no longer in equilibrium. The out-of-balance tensile stress on the top is reduced by the mesh contracting while the out-of-balance compressive stress on the bottom is reduced by the mesh expanding, resulting in the deformed shape you show on the right. If you left gravity on, the mesh would remain close to horizontal.

Regards,
Peter