I am trying to simulate  human foot in standing condition. I am interested to calculate stress, pressure and stiffness on foot pad to optimize the geometry and lattice density. The material for foot is selected as structural steel (rigid) and for pad is hard rubbed (flexible). I tried the case in explict dynamics but while exporting in topology optimization the objective function is showing question mark. I am searching for compliance but only mass and volume is available to choose. please look into the file attached and suggest me solver setting. it is also showing error when i tried solved to solve in static structural.  

error: The solver engine was unable to converge on a solution for the nonlinear problem as constrained.  Please see the Troubleshooting section of the Help System for more information.

warning: Large deformation effects are active which may have invalidated some of your applied supports such as displacement, cylindrical, frictionless, or compression only.  Refer to Troubleshooting in the Help System for more details.

warning: The unconverged solution (identified as Substep 999999) is output for analysis debug purposes. Results at this time should not be used for any other purpose.

Solver output