Spatial Poisson processes for fatigue crack initiation

Spatial Poisson processes for fatigue crack initiation

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.​​​​​​​​​​
Ivo Babuska, Zaid Sawlan, Marco Scavino, Barna Szabó, Raúl Tempone
Fatigue crack initiation, Linear elasticity, Notched metallic specimens, Spatial Poisson processes, Fatigue-limit models, Maximum likelihood methods
2019
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 (S-N) curves with averaged effective stress, σeffΔ(x), 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