Risk Analysis for Modeling Damage at Multiple Sites
Final rept 23 Sep 92-31 Jan 94
CSA ENGINEERING INC PALO ALTO CA
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In this first phase of a two phase study to develop a computer program for risk analysis of fatigue damage at multiple sites, the computer code PROF was demonstrated to be applicable to the multi-element damage MED problem. The application requires the damage tolerant analysis and crack size input for each of the relevant structural elements and for the relevant combinations of intact and failed conditions of the subcritical structural elements on the critical elements. The demonstration was preformed incorporating the effects of two subcritical elements on the failure probability of the chordwise joint at WS405 of the C-141 airframe. The application of PROF in the MSD area is not as clear. Since the largest crack in a lap joint will grow the fastest, the population of crack sizes to be modelled should be defined in terms of the largest crack in the zones of equivalent stresses. The sizes of the cracks in the holes immediately adjacent to the largest crack must be accounted for but several studies have indicated that the sizes of the cracks in more remote holes are not important drivers. Reasonable scenarios can be defined to bound the fracture probabilities given complete damage tolerant analyses and crack size data.
- Transport Aircraft
- Computer Programming and Software