NASA/TP-97-206238, Verderaime, V., Inherent Conservatism in Deterministic Quasi-Static Structural Analysis, Structures and Dynamics Laboratory, Science and Engineering Directorate, NASA Marshall Space Flight Center, AL 35812, November 1997, pp. 40, Format(s): PDF 325k |
The cause of the long-suspected excessive conservatism in the prevailing structural deterministic safety factor has been identified as an inherent violation of the error propagation laws when reducing statistical data to deterministic values and then combining them algebraically through successive structural computational processes. These errors are restricted to the applied stress computations, and because mean and variations of the tolerance limit format are added, the errors are positive, serially cumulative, and excessively conservative. Reliability methods circumvent these errors and provide more efficient and uniform safe structures. The document is a tutorial on the deficiencies and nature of the current safety factor and of its improvement and transition to absolute reliability
| Keywords: | safety factors, deterministic method, error propagation laws, safety factor conservatism, structural reliability, first order reliability, structural failure concept, safety index, mises failure criterion |
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| Subjects: | Engineering: Structural Mechanics: Stress Analysis |
| ID Code: | 446 |
| Deposited On: | 19 July 2002 |