Evaluation of fatigue crack initiation using accumulated entropy

TL;DR

This study uses accumulated entropy to evaluate fatigue crack initiation in stainless steel 304, analyzing thermography data and deformation effects to understand crack growth under cyclic loading.

Contribution

It introduces a novel application of accumulated entropy for crack initiation assessment and incorporates anelastic deformation effects into the analysis.

Findings

Accumulated entropy remains nearly constant during crack initiation.

Notch radius influences thermography measurements of crack growth.

Anelastic deformation affects temperature evolution at the start of testing.

Abstract

The accumulated entropy is used to evaluate the initiation of crack in flat notched specimen made of stainless steel 304. Two notch radii have been studied to capture the thermography of crack initiation and measure accumulated heat dissipation. It has been observed that under pull-push loading with an R-ratio of -1, the accumulated entropy for crack initiation and crack length's growth up to a specific number, Fracture Fatigue Entropy remains nearly constant. Anaclastic deformation dissipation has been taken into account and a mathematical model based on Kelvin-Voigt type element has been discussed. The effect of anelastic deformation has been studied in terms of temperature evolution at the beginning of the test.