This week I participated in an NESC conference in Los Angeles. One of my colleagues brought up the following point.
Finite element models are created to represent physical models for analysis purposes. The finite element model natural frequencies can then be compared to data from a modal test of the actual hardware. At this point, the finite element model can then be “calibrated” so that its fundamental frequency agrees with the test results. This can be done, for example, by scaling the elastic modulus in the analytical model.
There are two problems with this approach:
1. The analytical model no longer “matches the drawing” of the hardware, (although this is an inherent flaw in all models to some extent).
2. Changing the elastic modulus will throw off any dynamic stress calculations.
This dilemma deserves further thought…