Study of Crack Front Distribution During Crack Propagation Stage in High Performance Alloys.
Annual rept. 15 Sep 83-14 Sep 84,
RHODE ISLAND UNIV KINGSTON DEPT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS
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A stochastic model describing the crack evolution and scatter associated with the crack propagation process has been built on the basis of the discontinuous Markovian process. In this model the distributions of both the propagation life necessary to reach a specified crack length and the crack length at a specific number of cycles are derived in terms of constant probability crack growth curves. The significance of this model is that, by considering the crack growth curve obtained using any continuum model as being the mean growth curve, the present model is sufficient for the identification of the crack evolution and associated scatter without the necessity of performing scatter experiments. The validity of the model is established by comparing crack growth curves generated to Al 2024-T3 and Al 7075-T6 at specific loading conditions with those experimentally obtained and reported in literature. Emphasis is place, during the development of the model, on its adherence to the physical aspects of the crack growth mechanism and the degree of agreement between theoretical results and corresponding experimental data.