From the course: Autodesk Nastran In-CAD: Dynamic Analysis
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Modal and direct methods - Nastran In-CAD Tutorial
From the course: Autodesk Nastran In-CAD: Dynamic Analysis
Modal and direct methods
- [Instructor] Now in this video we're going to talk about the difference between modal methods and direct methods of solution. And the transient response and frequency response are split into these two fields. When we're thinking in modal methods, an example might be, the first four Mode Shapes of the plates that we see here. These are the Eigenvectors, or the Mode Shapes, we call them Phi one, Phi two, Phi three, and Phi four. So the Normal Modes analysis can store these Mode Shapes, we're going to see an example of what we call a Modal Database in Autodesk Nastran, an MDB where these can be stored away. So that database, we can think of like a big storage bucket which is saving the Mode Shapes, so those four Mode Shapes saved off in the Modal Database. The stored Mode Shapes, or Eigenvectors, can be then used in response analysis. We're going to see examples where we can very nicely re-use this data. In transient response excitation, we have a particular deflection shown at 0.097…
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