# Deformation and stress in moment of hit (Ansys)

This how task goes: i need to find deformation and stress of piston in moment of hit between piston and tool (tool is stationary). Velocity of a piston is (5-7 m/s) and forces are in picture below. I was analyzing it in "Transient Structural" because of a low velocities, but it seems not to work out.

1. Why i can't fixate a tool by "Fixed Support" or "Displacement" (i can't choose any geometry)?

2. Do i need to make any "Contact" or "Body Interaction"?

3. What time to put for a solution? (I didn't quite understand this part)

• Why not consider things like impact testing, see google.com/… Commented Apr 27, 2020 at 9:10

• "Time for a solution" is something asked by the software? I guess it might be the total time of the analysis. Considering that to model car crashes we usually run 250ms simulation, in your case 100 ms might be enough... You will have to verify it though by checking that the stress field in the part of interest has reached a stable state (that the wave of stress created by the shock should have gone through all your part). You can also estimate it better by using the speed of sound $$v$$ of your the material that your part is made of and its dimension $$L$$:
$$t \approx L/v$$