Pressure modeling with Shell41

[UMEngineer]

I have poked around the documentation for quite a while now, and have searched high and low for an answer, but I cannot seem to come up with the right one. I have been tasked with using ANSYS to model something very similar to a pumpkin balloon. I've decided to start small and model a small square of the fabric with a pressure behind into the tenons that keep the structures shape.

This is where I run into my problem. When I apply a pressure load to the fabric, I get no deformation at all. Because we only have access to the student version of Ansys, I am using SHELL41 with the cloth only option, along with Orthotropic Elastic for the material model. The fabric is still under going testing so the numbers are slightly fudged, but I am using the properties of rubber just to get a basic idea. It's a simple 1x1 foot square with a pressure of 4 PSI applied to one side. I have tried putting DOF constraints on combinations of lines, nodes and keypoints, but I still do not get the bulge I should be seeing. I am at a loss right now, and have come to seek help.

Thanks.

 

[UMEngineer]

Any ideas at all?

 

[Drej]

I would try using SHELL181 with the membrane-only option activated. It's worth a try. It's difficult to offer advice without knowing the details, but would check rigorously the material model parameters you use and possibly going with some standard constitutive model first (such as steel with a modified modulus maybe) and then build up to using the more complicated material models.


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