From the course: Autodesk Nastran In-CAD: Dynamic Analysis

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Stiffness modeling in dynamics

Stiffness modeling in dynamics - Nastran In-CAD Tutorial

From the course: Autodesk Nastran In-CAD: Dynamic Analysis

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Stiffness modeling in dynamics

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- [Instructor] In this video, we're going to look at some of the things which affect the stiffness distribution inside of modeling dynamics. So, in other words, stiffness modeling, and one of the first things is the mesh density, and that's controlled by the highest order mode shape. We look here at, say, mode 10, 2,000 hertz, and we've got to have a very fine mesh to capture that shape. Both mode nine and mode 10 are complicated shapes. If we don't have a fine enough mesh, then we don't capture the shape, and in fact, it usually ends up over-stiff. We're going to run an example where we actually deliberately set up a very poor mesh, and so now the mode nine and 10 are completely different. In fact, they're probably not realistic, and they're probably nonsensical. We have to have adequate mesh to capture that higher frequency content. What can happen though is that the very coarse mesh I've got there has actually captured pretty well what we call the first extensional mode and the…

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