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Showing results for tags 'nonlinear analysis'.
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Dear all, Lately I am having some problems solving a problem that might seem "trivial", however I am still having problems getting some meaningful results. As seen from the files attached, the problem consists of two aluminium plates connected with a steel bolt and a bushing. There is a press fit of 0,2mm (if I remember well) between the bushing and the two plates. The upper plate has one of its sides fixed and a compressive force of 90 kN is acted on the lower plate. Although I have simulated the contact* between all components (plates, bolt, bushing) and ran a quassi static NL analysis, I keep getting extremely high stresses at the area seen on the attached picture. It is probably some mistake with the contact there but I cannot find it. Please have a look on the attached .hm file. There are no contacts defined to allow you to use your own approach to the problem. You can use any of the latest HM versions to setup the problem. Thank you in advance for your kind assistance. *: a number of approaches used: friction, no friction, slide, freeze etc. bolt_coupon.hm
Hi All, I'm doing nonlinear quasi-static analysis in Optistruct. in order to better undestand the convergence of the simulation (expecially in case of non-convergent solution), it could be helpfull to output the residual in Hyperview. Is there a way to do this? regards, Luke31
Hello, I would like to have your expert opinion in one of the problems I am currently working on. Part of the simplified geometry is shown in the attached picture. As seen I have two cylindrical parts in contact with an interference fit of 0.001 inches. In addition to that a pin is installed and goes through (with a size to size connection) both cylindrical parts. I decided to perform a quasi static non-linear analysis, firstly by solving the interference fit and pin connection load case and then continuing with the load on the structure as a second load case. When I solved the press fit problem (without the pins), I had no problems, both the displacements and the stresses looked reasonable. But when the pins are included into the solution I am having a band of peak stresses (well beyond the material's yield point) where the pin contacts both cylinders (see red oval in the attached pic). This happened with almost every type of contact connection I tried between the pins and the cylinders (freeze, slide, friction etc). Same results when I replaced the 3D pins with 1D elements with RBE2 connections (to connect them with the cylinders). One solution is to ignore the pins and continue with my solution and then perform a detail stress analysis of the pins based on my results, but before doing so, I would like to know that I have tried all possible scenarios with the pins' contact. Any suggestions? Thank you in advance. pin.bmp
Hi all, I'm trying to learn about the random vibration analysis. From what I know, RVA uses the modal superposition method as its basis. Since it uses the modal superposition, it implies that random vibration analysis is a linear dynamic analysis. Lets say if you have a model with two or more parts, and you define some connection (spot-welds or elastic beams Rbe3) for them. The connection usually will introduce nonlinearity into the system. So then, in the end, I'm guessing the analysis will output nonlinear solutions. The thing that I have trouble understanding is that how is it possible to start out with a linear analysis and end up with a nonlinear solutions? Doesn't the nonlinear random vibration analysis violate the superposition method that it uses as the basis? Any comments or tips would greatly appreciated. Regards,