A Study of Analog Programming for Prediction of Crack Growth in Aircraft Structures Subjected to Random Loads
Final rept. Sep 1976-Jun 1977
MASSACHUSETTS INST OF TECH CAMBRIDGE AEROELASTIC AND STRUCTURES RESEARCH LAB
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Results of a program to study an analog approach to risk analysis of random-load crack growth are presented. The two major objectives were to implement certain specific simulations of crack growth on hybrid analogdigital hardware, and to develop an improved approach to the modeling of random loads. Under the first objective, all but two of the specific simulations were implemented and verified. One not implemented required hardware unavailable at the installation utilized for the simulations. The other was identified as not condusive to analog simulation. These simulations utilized a damage parameter rather than crack size itself as the random variable to provide well behaved and stable analog behavior. Under the second objective, a method of generating load statistics by direct inspection of large quantities of flight data was developed. In the course of this development, the applicability of estimation theory to the present problem was identified. The techniques of estimation theory, applied to analysis of damage in terms of an appropriately chosen damage parameter, promise to provide improved efficiency and accuracy in aircraft fatigue damage risk analysis.
- Computer Programming and Software
- Computer Hardware