Discussion Forum

Posted: 9 years ago 25 août 2015, 14:40 UTC−4

Hi normally there are no tricks, nor bugs, but for us out here on the Forum to understand really what is your issue we would need far more info, best the model itself. In Structural you have only the mechanical behaviour, while in Electromechanics you have normally coupling of electric and mechanical effects. So if you are i.e. talking about an electrostatic actuator model, you will have a very non-linear pull-in effect in electro-mechanics, by coupling the electrostatic forces and the mechanical deflection, while in structural, if you put a linear force BC you will get a linear response out. But you do not really tell us what is different in your case between the two physics and models you are using, so I cannot guess any better ;) -- Good luck Ivar

Posted: 9 years ago 25 août 2015, 20:34 UTC−4

Hello Ivar, Thanks for your valuable answer. To make it clear, I am simulating the parallel-plate capacitive sensor, with upper electrode as flexible diaphragm and bottom one mechanically fixed as another electrode. In Solid Mechanics, I constrained edge of diaphragm and applied pressure to see the output deflection over pressure, that's something really simple. In Electromechanics, I chose the same material, Linear Elastic Material and Solver setting for diaphragm, adding a air gap as dielectric material without any mechanical properties, and defined electrical terminals for both topper and bottom eletrodes, to see the output deflection over pressure and its corresponding capacitance change . After simulation, the deflection results from Solid Mechanics and Electromechanics are different, up to 30%. The solid Mechanics gives the value the same to theoretical calculation with linear output, but that from Electromecahnics shows nonlinear deflection. When I chose the Linear Elastic Material as "imcompressive" and "linear strain over stress" in Electromechanics, it gives closer results to that in Solid Mechanics, but I didn't chose these two options in Solid Mechanics. So I wonder if it is a bug there. [QUOTE] Hi normally there are no tricks, nor bugs, but for us out here on the Forum to understand really what is your issue we would need far more info, best the model itself. In Structural you have only the mechanical behaviour, while in Electromechanics you have normally coupling of electric and mechanical effects. So if you are i.e. talking about an electrostatic actuator model, you will have a very non-linear pull-in effect in electro-mechanics, by coupling the electrostatic forces and the mechanical deflection, while in structural, if you put a linear force BC you will get a linear response out. But you do not really tell us what is different in your case between the two physics and models you are using, so I cannot guess any better ;) -- Good luck Ivar [/QUOTE]