A comparison of fixed-base and driven-base modal testing of an electronics package
This paper compares results for a fixed-base and a driven-base modal test of an electronics package. A fixed-base modal test uses the common testing procedure of attaching the structure to a large inertial mass which is freely suspended. The problem with this approach is that the input levels are typically limited by the strength of the structure and stinger attachment. An attractive alternative to fixed-base modal testing is to use high force shaker-tables to provide a driven-base input. Some of the issues of concern are: properly simulating the fixed boundary conditions, applying modal estimation algorithms to motion-to-motion frequency response functions vs. motion-to-force frequency response functions, non-linearity effects and testing at very low input levels vs. levels equal to those of the field environment, complications involved with shaker resonances, exciting the ''response-critical'' modes of the structure, and consistency of the modal parameters using driven-base tests vs. fixed-base modal tests. Experimental results are presented which demonstrate the adequacy of using vibration shake tables to excite the fixed-based modes of the system. A direct comparison of the modes acquired using fixed-base and driven-base excitation for the electronics package shows very close agreement. A discussion of the theory for driven-base testing is given, as well as a brief presentation of analytical predictions for the structure. 4 refs., 11 figs., 1 tab.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5733099
- Report Number(s):
- SAND-88-1765; ON: DE89016673
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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