Hi everyone,

constant pressure on the shell that contacts with particles is needed in the powder-friction-test. I can realize the movement of the rigid shell by defining the pressure with no particle involved, as shown in Fig.1. But after adding particles (transformed from C3D8R), the movement of the shell becomes out-of-controlled (it goes up suddenly) as shown in Fig.2. Does anyone know what happened? Thanks for your guidance!

Abaqus ​​​​​​​