Fatigue Crack Propagation under Random Loading

Abstract

To supply data needed for a rational fatigue design of structures subject to random load there must be some appropriate testing methods which are able to reproduce a specified time history of the random variable such as load, stress, strain and stress intensity factor and also must be inexpensive to be popular ones.With a small micro computer system alone, it is very difficult to perform exact experiments considering the dynamic characters of the test system varying as the fatigue damage accumulates in the specimen. In this report, two Micro Processing Units are used to perform experiments with or without response compensation by FFT. Stationary Gaussian random processes are generated with a large computer and data are packed into special forms to be sent through TSS within a reasonable time.The developed soft and hardware are satisfactory and fatige crack growth tests under a stationary random stress intensity factor showed the effect of the compensation and indicated the possibility of a simplified and less time consuming test method without response compensation.