WIT Press

Fatigue Crack Growth And Interactions


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WIT Press


P. Brož


An algorithm to model 2D crack growth is given. The stepwise technique on the pattern of local criteria of growth is employed, together with two propagation criteria. At the first phase of growth, the maximum tension stress gauge is used to consider the sudden variation in tangent course, and at ensuing stages, the supposition that the stress intensity factor K2 = 0 at the current crack tip is utilized. Further, to investigate the interactions of a fatigue crack and a microdefect such as a void, a rigid inclusion or a transformation one, the mixed boundary integral equation method is applied. The pseudo-tractions technique is used to study the influence of a transformation inclusion. An element incorporating the mixed-mode stress intensity factors is employed to describe the singularity at a moving crack tip. The analysis of a crack issuing from a circular hole in a finite plate is presented. Keywords: angle of deviation, displacement discontinuities, inclusion, microdefect, round arc. 1 Introduction In the main, the work tackling numerical simulation uses the stepwise procedure to model crack growth. Concurrently, the crack path is taken into account to be a sequence of small steps. At each step of propagation, the crack is extended from the previous tip by a length increment δl in some course that may be determined from the growth criterion chosen. The criterion of maximum tensile stress was used as a matter of priority. The SIFs encompassed in this criterion are specified by dint of boundary element or finite element methods. This conception results in the crack path that looks like a jigsaw line, in defiance of the expectation of a smooth crack path. To arrange a smooth path, the only stepwise algorithm was proposed. It is based on the use of maximum tensile stress criteria. In compliance


angle of deviation, displacement discontinuities, inclusion, microdefect, round arc