# A Life Prediction Model Considering Material Ductility in Multiaxial Fatigue Damage Analysis

## TL;DR

This paper introduces a new model for predicting material fatigue life by considering material ductility and stress interactions during crack propagation.

## Contribution

A novel multiaxial fatigue damage parameter that accounts for material ductility and stress interactions without new material constants.

## Key findings

- The new model reliably predicts fatigue life across various verification materials.
- The model captures microcrack propagation effects like friction and interlock on crack surfaces.
- No new material constant is required, simplifying the model's application.

## Abstract

In this paper, a novel multiaxial fatigue damage parameter was developed based on the critical plane-energy method. The proposed damage parameter considers the sensitivity difference of the material ductility to the out-of-phase loads and takes the function of material elongation as an adjustment function. At the same time, the mutual promotion of shear stress and normal stress in the process of microcrack propagation was considered to characterize the friction and interlock phenomenon on the crack surface in the new parameter. It is indicated that the new model has reliable prediction results for all verification materials. Furthermore, the new model also has the benefit of not requiring the introduction of a new material constant.