Avaliação da propagação de trincas em problemas de fadiga por fretting através da implementação de um método semianalítico

Abstract

The aim of this work is to evaluate the crack propagation in cylindrical contacts under fretting fatigue conditions in a Ti-6Al-4V alloy. For such, a semi-analytical method based on the distributed dislocation technique was implemented with the assistance of the Python programming language, which enabled the calculation of the stress intensity factor for the problem investigated. This parameter, in its turn, allowed the application of the Paris’ law in order to estimate the crack propagation life in fretting fatigue problems. These results were then compared to the number of cycles to failure of laboratory tests collected from the literature, where it was then possible to estimate the crack initiation life for the investigated problem. The initiation life was also determined for conventional fatigue tests, which allowed to evaluate the effect of fretting loads on crack initiation. In the end, it was possible to verify that crack nucleation occurs faster in components subjected to fretting loading, which is in agreement with observations from previous works. Furthermore, it is worth noting that the methodology for calculating the stress intensity factor implemented in this work takes into account the effect of the finite thickness of the specimen in the analyses, which makes the solution more robust and closer to the real condition. It also presents a low computational cost, especially when considering fully numerical approaches such as the finite element method and the boundary element method.