Discussion Forum

Hey guys, I'm very new to COMSOL. I have a problem I'm hoping somebody with more experience can solve.

I am trying to simulate the displacement of an elastomer (PDMS) wall over time at different applied pressures. The wall is part of a larger PDMS geometry, the model of which is imported via the SolidWorks Livelink.

I have applied a hyperelastic domain to the body, using a Neo-Hookean material model. I have read that PDMS is a nearly-incompressible material, and have therefore selected that option. The applied pressure is in the form of a boundary load applied to the wall interior. A fixed constraint is applied to the bottom of my model, simulating an inextensible side of the geometry.

I want to measure the deformation of my wall when pressure is applied for 1 second. I have therefore used a time-dependent study. To measure what happens over a range of different pressures, I have also used an auxiliary sweep, listing my pressure parameter with a range of 100-1000Pa and steps of 50Pa.

To summarize, I want to see what happens when I apply different pressures to a PDMS wall. I want each of these pressures to be applied for 1s. All of this can hopefully be seen in the attached mph file.

The problem I have is that the study fails once the sweep reaches 650Pa, at the time of approximately 0.15s. The following error message is shown: "Parametric solver stopped. Not all parameter steps returned." When I check my log, I see that the step sizes reduce to a very small number to the order of 10^-12 right before the study fails.

I have tried starting a new study with an auxiliary sweep range of 650 to 1000Pa. The same result occurs almost immediately. So I can only get data for up to 600Pa. The nature of my project means that I will be applying much higher pressures (in the range of 1-10psi), which I currently can't do.

Does anybody know where I'm going wrong? I've tried to explain what I've done as well as I can, though it is very possible that I left out some critical info.

Thanks, Alex