Sensitivity of numerically modelled crack closure to material

Abstract

Crack closure is a phenomenon which slows down fatigue crack propagation and leads to higher residual life of components and to a change in the crack front curvature. Because of the significant impact on the fatigue crack growth rate, the scientific and engineering community has been trying to describe this phenomenon very precisely. One of the most frequently described closure mechanisms is plasticity-induced crack closure (PICC) which is dominant in the Paris regime. In the presented work, a CT specimen has been modelled three-dimensionally and the PICC estimations have been done for different models of materials to investigate their sensitivity. The models were cyclically loaded by forces inducing maximal stress intensity factor of 17 MPam at the load ratio R=0.1. The crack was curved according to conducted experiments. Even though Newman’s equation estimates PICC almost constant, differences were observed from finite element simulations.Crack closure is a phenomenon which slows down fatigue crack propagation and leads to higher residual life of components and to a change in the crack front curvature. Because of the significant impact on the fatigue crack growth rate, the scientific and engineering community has been trying to describe this phenomenon very precisely. One of the most frequently described closure mechanisms is plasticity-induced crack closure (PICC) which is dominant in the Paris regime. In the presented work, a CT specimen has been modelled three-dimensionally and the PICC estimations have been done for different models of materials to investigate their sensitivity. The models were cyclically loaded by forces inducing maximal stress intensity factor of 17 MPam at the load ratio R=0.1. The crack was curved according to conducted experiments. Even though Newman’s equation estimates PICC almost constant, differences were observed from finite element simulations.