Learning Forum

[3343534645]

I've been trying to implement eigenvalue buckling simulation for solid elements using MATLAB to perform linear buckling analysis. When calculating the geometric stiffness matrix for eigenvalue buckling, I referred to ANSYS documentation Help 3-61: https://www.mm.bme.hu/~gyebro/files/ans_help_v182/ans_thry/thy_geo3.html. However, after trying it out, I found that the geometric stiffness matrix calculated using the formula differs from the one output by ANSYS APDL, which makes me doubt the result. Does anyone know how to solve this? I’d appreciate any help or advice from experienced folks.

 

[3343534645]

I derived Cook's theory and also rewrote Borst's theory. When they introduced the calculation formula for the geometric stiffness matrix of solid elements, the geometric stiffness matrix they computed had non-zero elements. Why is the geometric stiffness matrix output by ANSYS APDL entirely composed of non-zero elements? Was the calculation incorrect?

[3343534645]

Thank you for your reply. Could you recommend any literature? I would also like to personally implement linear buckling analysis in MATLAB and benchmark it against ANSYS, which would be a very rewarding task! Thank you so much!

[3343534645]

Why haven't any ANSYS staff responded to me? Recently, I also tried Němec's theory (http://creativecommons.org/licenses/by/4.0/). However, the geometric stiffness matrix calculated from the theoretical formulas still doesn't match the one in ANSYS APDL. What could be the reason for this? I sincerely hope that someone knowledgeable can resolve this long-standing confusion for me.

[bonnietracks1]

Implementing eigenvalue buckling analysis for solid elements involves using the linearized buckling method, which computes the critical load factors at which a structure becomes unstable. This is typically done in finite element analysis (FEA) software, but it can also be implemented from scratch or in custom codes using linear algebra libraries.

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[emmamiaa867]

Eigenvalue buckling with solid elements can be tricky honista APK—make sure your mesh is refined enough and that boundary conditions match real-world constraints. Also, using weak springs or stabilization can help if the model is unstable.

[jamesrichered753]

It’s great that you're working on eigenvalue buckling in MATLAB. The discrepancy with ANSYS may come from element formulation differences or how boundary conditions are applied. Double-check your stress distribution and integration scheme. Also, ensure your geometric stiffness matrix matches the stress state used in ANSYS. zombiecatcherapk.com