Spatial Poisson processes for fatigue crack initiation

by Ivo Babuska, Zaid Sawlan, Barna Szabó, Raul Tempone
Year: 2019

Bibliography

Babuska, Ivo, Zaid Sawlan, Marco Scavino, Barna Szabó, Raúl Tempone, "Spatial Poisson processes for fatigue crack initiation"Computer Methods in Applied Mechanics and Engineering, Volume 345, 1 March 2019, Pages 454-475.​

Abstract

​In this work we propose a stochastic model for estimating the occurrence of crack initiations on the surface of metallic specimens in fatigue problems that can be applied to a general class of geometries. The stochastic model is based on spatial Poisson processes with intensity function that combines stress-life  curves with averaged effective stress, σeffΔ, which is computed after solving numerically the linear elasticity equations on the specimen domains using finite element methods. Here, Δ is a parameter that characterizes the size of the neighbors covering the domain boundary. The averaged effective stress, parameterized by Δ, maps the stress tensor to a scalar field upon the specimen domain. Data from fatigue experiments on notched and unnotched sheet specimens of 75S-T6 aluminum alloys are used to calibrate the model parameters for the individual data sets and their combination. Bayesian and classical approaches are applied to estimate the survival-probability function for any specimen tested under a prescribed fatigue experimental setup. Our proposed model can predict the initiation of cracks in specimens made from the same material with new geometries.​
 0045-7825

Keywords

Fatigue crack initiation, Linear elasticity Notched metallic specimens, Spatial Poisson processes Fatigue-limit models Maximum likelihood methods