Needle Piercing Simulation: Abnormal Results (Solid Mechanics, Stationary Study)

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Dear all, For the past week, I've been trying to set up a simulation comprising an arrow-like needle piercing a skin-like substrate. As I haven't found a similar (3D) example in COMSOL's Application Gallery or Learning Center so far, I have followed analytical step-by-step instructions by three different AI chatbots (Gemini, Perplexity, Claude). After days of trial-and-error and diagnostic tests, I have reached the point where all three of them agree with each other that my method was set up correctly. Nevertheless, the results (see 1.png in attachments) indicate abnormally low pressure values on the needle, with the appearing scale being on the order of E-4 N/m2 (whereas, e.g., atmospheric pressure is at E5 N/m2), while zero pressure appears on the skin-like substrate. The AI chatbots claim that the needle is faulty (it's an imported .stp file from Autodesk Inventor), but I cannot really trust them. All my Model Builder data can be seen in the 2.png attachment. I'm also attaching the simulation file (NP.mph).

Any kind of help will be sincerely appreciated! Thank you everyone in advance.



1 Reply Last Post 21 mai 2026, 04:53 UTC−4
Acculution ApS Certified Consultant

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Posted: 1 hour ago 21 mai 2026, 04:53 UTC−4
Updated: 1 hour ago 21 mai 2026, 04:59 UTC−4

You have a negative sign on the parameter disp under the Prescribed Displacement, but also a negative sign on the values for disp in the parametric sweep. So, the needle is moving the wrong way. There is probably a lot more to it than that, but that must be an important point.

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René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
You have a negative sign on the parameter disp under the Prescribed Displacement, but also a negative sign on the values for disp in the parametric sweep. So, the needle is moving the wrong way. There is probably a lot more to it than that, but that must be an important point.

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