Hi everyone,

I am trying to simulate a drop test to see whether a shield protection is effective or not with solidworks simulation professional.

I have a disk that is travelling at 40 m/s hitting a static steel protection structure bolted at ground (see fig below).

I know that with SW sim professional I can't simulate the effective impact between the two bodies but I would like to know if there is a way to do that "approximately" anyway.

I thought this alternative:

1) evaluate the normal and tangential distributed stiffness of the protection through a static simulation where I apply a unit distributed pressure P = 1 (N/m^2) on one direction and then evalute the displacement u (m) of the structure in the same direction. Then the distributed stiffness is = P / u [(N/m^2)/m]. (NOTE: with this option I get very low stiffness values compared to the drop tests tutorials)

2) run a drop test sim of the disk, setting the target to be flexible with the same stiffness values of point 1). (NOTE: what thickness should I apply to the target considered that the protection is a mix of UPN beams for frame and sheet metal as cover)

3) check the max. stress of the simulation at point 2) and then apply it with a static simulation to the steel protection structure to see whether the protection is effective or not.

What is your opinion? Any other strategies (especially to calculate the effective stiffness)?

I have already started simulating this way but, as mentioned, I am obtaining very low stiffness values (2.9E9 (N/m^2)/m)...

Thank you very much for your help

Not to be the bearer of bad news but I don't think this will be possible even as an approximation with Simulation Professional. With the tools you have now I'd recommend using the Linear Static study as qualitative tool to improve the design applying some estimated loads in various locations and trying to reinforce any weak point areas.

I'm assuming the projectile is of substantial mass and stiffness (such as a a steel disk, flying at a high velocity)

Generally protection systems require nonlinear analysis because they are more focused around energy absorption / dissipation than outright peak stress.

Ask yourself "Would it be acceptable if the puck left a dent in the sheet metal as long as it didn't damage anything or cause risk to anyone on the other side?"

If the answer is yes (which it almost always is for protection systems) then you just proved that Linear Static can't solve this because of the permanent deformations. I guess it could solve for a drastically overbuilt scenario (something akin to the steel plate you'd need to keep stresses below yield)

Making some assumptions with a nonlinear static approach, the kinetic energy of the projectile could be hand calculated, and then apply load to the structure and integrate the area under the response curve to calculate energy absorbed. Identify the load step where the energy absorbed exceeds the energy from the projectile that is expected to be transferred then make determinations about the state of the design at said load step.

With nonlinear dynamics you could conceivably simulate the entire process including the projectile body with appropriate initial conditions. But for this type of analysis other tools such as Abaqus/CAE are really the preferred approach and would have an easier time with the contact interactions between projectile and surfaces.