Analysis of the stress intensity factor along the thickness: The concept of pivot node on straight crack fronts

摘要

This paper focuses on calculating and analysing the thickness and load level influence on the stress intensity factor distribution along the thickness, both individually and together. The main objective is improving the knowledge about the small region existing near the surface where the stress intensity factor results remain independent of external factor as load level or thickness. It is found that this phenomenon occurs around a pivot node within the crack front (P_1) that presents advantages for the correlation of numerical and experimental studies. The work evaluates the finite element model of an Al 2024-T35 compact tension specimen with no plastic wake effect introduced. The three-dimensional behaviour near the crack front is simulated through numerical analysis with ANSYS code, and J-integral method is used to determinate the curves of K evolution along the thickness. The results are studied according to a series of parameters that characterize the curves. Conclusions are presented on the areas of influence of each factor involved.