"Fatigue Life Model Using Defect Size, Stress, and Life Validated by Te" by Daniel G. Miller, Ryan A. Kemnitz et al. 10.2514/6.2022-4128">
 

Fatigue Life Model Using Defect Size, Stress, and Life Validated by Tension and Vibration Testing

Document Type

Conference Proceeding

Publication Date

6-27-2022

Abstract

The fatigue life of an Additively Manufactured (AM) component is dependent on defect sizes and locations formed during the manufacturing process. One model to predict fatigue failure based on defect size is the El-Haddad model, which has been extensively tested as the boundary between fatigue limited behavior and finite fatigue life. In recent years, the model has been adapted to predict finite fatigue life under simple, uni-axial load conditions with a maximum applied stress and expected maximum defect size. The work here extended the development of the model to a 3D view to analyze both the stress/defect size relationship of the El-Haddad model and the stress/life relationship of the traditional S-N curve with respect to AM defects. Experimental data included uni-axial loading of fatigue bar samples as well as bending load cases for a turbine blade geometry. The resulting El-Haddad model was linked to Finite Element Models (FEMs) of the turbine blades to relate defect locations to applied stress states at the defects. AM test specimens were printed from nickel-based superalloy 718 and subjected to stress relief heat treatment, age hardening, and surface clean-up. Experimental results included defect sizes, locations, and measured life. Comparing the experimental data to the predicted fatigue lives based on the fatal defects demonstrated the validity of using one model for both the axial and bending load cases.

Comments

The full text of this paper is available from AIAA via subscription or purchase through the DOI link below.

Source Publication

AIAA AVIATION 2022 Forum

This document is currently not available here.

Share

COinS