Influencia de diferentes parámetros en la propagación de grietas a fatiga considerando efectos en punta de grieta

Abstract

A reliable fatigue crack growth prediction (FCGP) results from an optimal material characterisation and proper use of finite element models (FEM) or analytical expressions available in the literature. In practice, two-dimensional assumptions are assumed, and local phenomena such as plasticity-induced crack closure (PICC) that significantly influence crack growth are not properly considered. Therefore, the work aims to develop advanced three-dimensional models that consider the effect of PICC on FCGP. For this purpose, standardised specimens made of S275 structural steel widely used in the industry are used. The methodology followed is based on experimental tests to characterise the material and analyse the real crack behaviour and geometry, and numerical simulations using elastic-plastic FEMs that accurately reproduce the FCG. The main results of this work showed incongruities in the standard experimental characterisation of the material propagation curves, and a method to correct them was proposed; FEMs reducible to analytical equations that consider the PICC were implemented, and a methodology to quantify the numerical PICC for any stress ratio was developed.