1) Put three orthogonal planes through the center of your solid and Split the body three times. You now have 8 pieces. Keep the one piece in the positive quadrant and delete the rest. You will use three displacement conditions on those three cut faces. On the +Z face of the 1/8 model is where you need a thin block larger than the 1/8 body to press down on it. The symmetry plane on the -Z face of the 1/8 model will support that load.

HOW TO DO IT? DID NOT GET IT. can u explain it to me pictorially? 

i created the part in SOLIDWORKS. can i redesign it there itself. .? if so  WHAT SHOULD BE THE FINAL DIMENSIONS OF SPECIMEN TO BE USED FOR SIMULATION.?

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