Inventor 2025 Modal analysis: weird resonnance frequency

bguennecGS5A8 — Sat, 17 May 2025 06:54:34 GMT

Dear everyone,

I'm trying to reconfirm the natural frequency of test piece by Inventor Professional 2025.

The figure below is one result on the analysis I made using a hourglass shape specimen, where on end is fixed. This specimen is designed to show the resonance mode shown in the figure (tension/compression mode) at a frequency of 20 kHz in theory (already confirmed by other analyses and experimentally proven).

Using Inventor 2025, this mode is found at a frequency of approximately 12 kHz is found (see figure)

Further precision:

* a fine mesh has been implemented in this analysis (more than 300,000 elements). Sufficient for precise analysis.

* Material properties: E=206 GPa, density=7.85 g/cm3. Using another steel material preset in the software database do not considerably change the resonance frequencies. No effect of the dampling factor neither.

* Effect of the gravity has been checked and is negligible, which is reasonable since the specimen total length is 83 mm.

May anyone has an idea to explain this discrepancy between the analysis results and actual resonance frequency?

Than you very much.

Re: Inventor 2025 Modal analysis: weird resonnance frequency

JDMather — Sat, 17 May 2025 14:23:21 GMT

@bguennecGS5A8

Can you Attach the file here?

Re: Inventor 2025 Modal analysis: weird resonnance frequency

bguennecGS5A8 — Tue, 20 May 2025 02:36:49 GMT

Dear JDMather,

Thank you for your reply.

After additional check, I figured out a mistake from my own about the limit conditions and the corrected configuration gives a reasonable behavior.

Sorry for the inconvenience on this case.

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Inventor 2025 Modal analysis: weird resonnance frequency

Re: Inventor 2025 Modal analysis: weird resonnance frequency

Re: Inventor 2025 Modal analysis: weird resonnance frequency