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Hello, I have convergence problem when using NLGEOM key word for a structural simulation of an elastomer submitted to large deformation. To try to identify the issue, I have simulated something extremely simple: A 3mmx3mmx30mm sample submitted to uniaxial tensile stress. One of the two small...

Thank you for your reply, I will try it right away. I found a workaround by applying the pressure on the elements, but it is a little bit more work to select the correct elements. It is actually a little bit dumb of me to have gone in the right direction by selecting just the elements that were...

Hello, I am trying to model the deformation of a soft elastomeric cylinder, under the action of a compressive electrostatic force (i.e. electroactive polymer). To correctly model the situation, I should used couple physics, solve the electrostatic problem, compute the force, and then solve the...

This is perfect, thanks a lot. Samuel

Hello, This is a really dumb question, but I used to simulate membranes with an axisymmetric model (i.e. representing the cross section). For several reasons, I have now made a 3D model. According to PLNSOL documentation, I should be able to plot results (for example stress) of the membrane...

That is the approach I used, with good correlation between predicted results using Rayleigh Ritz approximation and measured results. Thank you all for your help

Thank you very much for your replies. I am measuring membranes which are 40 um thick and have a diameter of 2 mm. As I am exciting them at their first natural frequency, it means that the spatial wavelength of the oscillations is 4 mm. I have therefore a ratio Wavelength/Thickness of 100, and it...

I am looking for a formula describing the natural resonance frequency of thin circular stressed membranes with a fixed edge. I know the formula for the situation without stress, which depends on the membrane's geometry and mechanical properties (Young Modulus, Poisson coefficient). I have found...

DOH! Never mind, I turned my brain on and figured this out...

I have a simple question which is bothering me : If I take a clamped-clamped beam submitted to a uniformely distributed force, I can calculate its shape for a given force per unit length, as long as one stays with small deformation. Because the deflection at any position along the beam is...

What you describe is different from my problem, but is normal. I would suggest you read the help file for a more complete explanation, but in short, in an axisymmetric analysis, the Y axis (x=0) is defined as the axis of rotation of the model. It is therefore impossible to have any node with a...

Thank you for your replies. I indeed try to avoid high distortion of the mesh. If this happens I refine it and start again. But I need to run a couple simulations in a batch and then come back to the problematic ones. Your replies will help me to do so. Thanks a lot.

Hello, I am performing nonlinear analysis, and sometimes, if elements get very distorted, a dialogue box appears saying something like : Some elements have become highly distorted(...) The simulation stops until the user press on OK. This is rather anoying if a batch of simulation is run, for...

There is one thing I might have done wrong : I haven't set a SYMM boundary condition on the Y=0 line, for I thought it was implicit, due to the fact I defined the element with the axisymmetrical keyopt. I've tried with and without it with small actuation voltage and as I didn't notice any...

Hello, I am doing coupled field electrostatics/structural analysis. It means that I calculate an electrostatic force, then the displacement of the structure due to this force. After that I do a mesh morphing to calculate the new electrical field and electrostatic force, and so on until...

I don't think there is an analytical formula for a square diaphragm. I came across this apporximation though : V=Vo/2*P44*DP*0.2*(L/t)^2 I haven't checked it, so I don't know why the (1-nu) term is missing. It might be included in the 0.2 factor. I found this in a silicon-related book, so it...

Hello, Being myself a beginner in ANSYS in need of help, I can't help you with the ansys related questions, but to answer your first question, and assuming your diaphragm is circular, you would get the following formula linking the applied pressure to the voltage in full wheatstone bridge...

Hello, I am trying to do couple physics using physics files. I calculate a force , and then apply it to a structural model with the LDREAD function. Then I recalculate the force using the new geometry and after that I need to re-run the structural analysis and so on until convergence is...

I have some trouble to simulate coupled field physics and I hope that you will be able to give me advices. What I am trying to do is pretty simple : I'd like to model an elecroactive polymer plate. It is simply a dielectric plate of elastomer whose top and bottom surface are made conductive. A...

Thank you for your reply, I indeed only mesh the areas, so I don't need to use the LATT command. I thought I had to, because I was applying loads on lines, but if I'm not mistaken, this doesn't matter becuse loads are transfered to the nodes, and the nodes are created during the meshing of the...