Learning Forum

[Pouria Azarikhah]

Hi

I am simulating a needle penetrating in a plate in explicit dynamic module. I activated the erosion control in order to eliminate elements when they reach their failure criteria. How can I find the penetration depth in results? I found directional deformation which does not show the real penetration depth.

Many Thanks

[Armin_A]

Hi Pouria,
Is the needle initially at a prescribed distance from the plate (before running the simulation)? A picture of the setup would be helpful.
I also assume that the failure criterion is only applied to the plate and not the needle.

[Pouria Azarikhah]

Hi Armin

Thank you for your reply. The needle is attached to the surface of plate. The failure criteria are also considered for both plate and needle.

[Chris Quan]

Yes, it is true that the directional displacement may contain rigid body motion so it may not represent the actual penetration depth. You may click on Solution in Tree Outline and then click on Worksheet from the top toolbar of the Home tab. This will open a list of user-defined variables. The variables LOC_DEF(X/Y/Z) can give you the deformed location of the scoped nodes or vertexes. You need to carefully select the nodes that can represent the depth of penetration and then scope LOC_DEF to these nodes in the correct direction (X/Y/Z). Finally, you can calculate the penetration depth by calculating the difference of LOC_DEF at these selected nodes, either manually by hand or export them to Excel for calculation.

[Pouria Azarikhah]

Dear Chris

Thank you for your kind response. Additionally, I would like to find required directional force in back plate of needle over the time. Only a constant velocity during the penetrating is considered in my model. I obtained force reaction selecting backplate face which does not show accurate trend . On the other hand, I extracted equivalent von mises stress of elements below needle which show acceptable trend. How should I find the required penetration force? Many Thanks.