Conservatism in least favorable response analysis and testing
In order to assure that mechanical structures can meet design requirements it is desirable to test a structure using an input which is conservative but not a severe overtest. One method available for the specification of shock tests is the method of least favorable response. This method can be used analytically or in the laboratory and is guaranteed to provide tests which are conservative, at least in one sense. When the impulse response function, or equivalently the frequency response function, is available between a point of interest on a structure and the input point of the structure, and when we know the real function which envelops the modulus of the Fourier transform of all possible inputs which might excite the structure, then the method of least favorable response can be used to find an upper bound on the response which the point of interest on the structure can realize. We use this in the analysis of structural peak response. In the laboratory the least favorable response is generated experimentally, for example, by testing the structural unit on a shake table. If the structure survives the laboratory test, then we assume that it could survive any input in the class of inputs whose Fourier transform moduli are enveloped by the function used in the analysis. The objective of this study was to analyze the inherent conservatism of the method of least favorable response. A technique that can be used to do this is demonstrated. First, the method of least favorable response is reviewed and how it is used analytically and experimentally is demonstrated. Next the technique used to measure the conservatism in a least favorable response test is developed. Finally, the method is applied in some numerical examples where the degree of conservatism in the tests of some specific structures is measured. (LCL)
- Research Organization:
- New Mexico Univ., Albuquerque (USA). Dept. of Civil Engineering
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5065938
- Report Number(s):
- SAND-80-2093C; CONF-801033-2
- Resource Relation:
- Conference: Shock and vibration symposium, San Diego, CA, USA, 21 Oct 1980
- Country of Publication:
- United States
- Language:
- English
Similar Records
Conservatism implications of shock test tailoring for multiple design environments
Evaluation and control of conservatism in drop-table shock tests