Learning Forum

[KristofVC]

Hello everyone,

 

I am working on a modal analysis of a steel plate structure for my thesis. The structure is made up of welded steel plates, reinforced with a variety of stiffeners. My university has constrained me to using the student version of the software.

With the complexity of the structure, I easily surpass the limit of 30k elements that is present in this licensse. To reduce the amount of elements in the model, I would like to simplify some plates in the model by "incorporating" the stiffeners in the plate itself, by adding the added moment of inertia and mass directly to the plate itself. However, when I try to do this in Mechanical, the geometric parameters of the plates are locked. I have looked through the program to override these numbers, but so far I have been unable to do so. Can anyone lead me to the solution for this problem? Thanks in advance

P.S. Due to the NDA that I had to sign, I unfortunately am unable to attach the project file.

Thanks in advance for your help!

[peteroznewman]

Open the geometry in SpaceClaim and use the Midsurface feature on the Prepare tab to convert all the solid steel plates to surfaces, which will be meshed with shell elements.

You can do the same with the stiffeners, or you can convert the stiffeners to Beams using the Extract button on the Prepare tab.

By using shell and beam elements, you will easily keep this project within the Student license limits and get better results.

[KristofVC]

Dear Peter,

Thanks for your answer. Unfortunately, I already have modelled the structure using midsurfaces and lines for the stiffeners (using self made cross sections). Even with these simplifications I go well above the allowed element number.

 

Is there no way to manually assign moments of inertia and mass to a specific body in a structure?

[peteroznewman]

I would push back on the constraints of using the Student license if you have already done midsurface and beam elements and it still doesn't fit within the limits. The university should either provide a Research license or reduce the scope of the project to a much smaller part of the structure.

A beam element can have a user-defined cross-sectional area properties, so you could continue with the full structure with more abstraction. For example, you can model an entire building with 20 elements. You just won't have much fidelity in the results.

[Sand_1234]

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Hi Peter,

Does manually writing over the geometric section properties (Area, Moment along x and y axis) in spaceclaim properties section effect the analysis?

Thanks

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