Spring element extension does not match theory.

Hi Gavril, 

             The reason for this discrepancy would be that the simulation is not being pure static. Dytran is an explicit solver, which means it is primarily designed for transient dynamic simulations (e.g., crash, impact, blast, drop tests). Explicit solvers do not perform true static equilibrium calculations as an implicit solver (like MSC Nastran SOL101 or Marc) would.

If your simulation is not purely static, the mass might be oscillating around the equilibrium position, especially if there's no damping. This can momentarily lead to larger displacements. Try adding damping or running the simulation for a longer time to see if it settles at the expected 34.073 mm.

Hi Shank! Thank you for your reply!

I should have mentioned the the system is damped and the value of 68.12 mm is obtained after everything settles.

That's interesting. Then another possibility would be that the model is overdamped. It might seem like everything is settled down but may not have actually reached steady state. How are you applying the damping? And if you plot the deformation vs time graph, how does that compare with the theoretical one? 

That's interesting. Then another possibility would be that the model is overdamped. It might seem like everything is settled down but may not have actually reached steady state. How are you applying the damping? And if you plot the deformation vs time graph, how does that compare with the theoretical one?