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Author Topic: Flatwise Tension with solid elements  (Read 10053 times)

SD_Gabe

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Flatwise Tension with solid elements
« on: February 06, 2012, 01:12:12 PM »
I have a question with the way HyperSizer is calculating sigma-rr in the FWT calcs. It looks as though it is generating a Moment from the model (not from the facesheets) and using that to calculate the FWT. How is that moment calculated when using 3D solid elements?

Thanks.

SD_Gabe

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Re: Flatwise Tension with solid elements
« Reply #1 on: February 07, 2012, 11:36:51 AM »
As we looked closer at the analysis it looks like HyperSizer is using the stress in the 'Z' direction directly for the sigma-rr term. However, it seems to be using negative stresses for FWT calcs. I believe that is telling me it is using a compressive stress for a tension calc. Is it supposed to do that?

James

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Re: Flatwise Tension with solid elements
« Reply #2 on: February 07, 2012, 07:04:46 PM »

The (Sig_rr) normal stress  is computed for a solid element by averaging the Normal_Z stresses at each grid.

Sig_rr = Sig_Z Average (G1:G8)

This stress is passed directly into the Flatwise Tension analysis, the panel bending moments are not used to determine the Sig_rr. If the average stress is compressive, the Flatwise tension analysis should be disabled.

If you have a case that is behaving otherwise, could you please send me the example.