Session: MF-17-01 Advanced and Additive Manufacturing and Material Technologies (joint with D&A)

Paper Number: 62996

Start Time: Thursday, July 15, 2021, 09:00 AM

62996 - Prediction of Residual Stresses and Stress Intensity Factors in Fracture Mechanics Samples Manufactured by Laser Powder Bed Fusion 

The extent to which residual stresses in AM components affects the performance in a fatigue crack growth (FCG) test is not fully understood. The aim of this project is to develop a model of the AM  process for single edge notch samples of SLM 316L steel. This model will then be used to create a range of single edge notched bend and compact tension fracture mechanics samples for analysis, using varying construction methods. Finite element analysis methods will be used to analyse the residual stress relaxation at the crack tip in the models during simulated FCG tests, for comparison with existing test data. Experimental test results have shown that fatigue crack growth rates have decreased with crack length in a limited number of tests performed and the reasons for this not explained by metallurgy. A possible explanation is that that large residual stresses exist, which combine with the applied load to generate amplified stresses at the crack tip i.e. the total stress intrenisty factor K, is the sum of that from the applied load, K_p.  and residual stress, K_s. These crack tip residual stresses are expected to decrease as the crack propagated through the sample, and hence even is the value of K_p increases with crack length the total value of K will decrease. In this work the residual stress field and K_s at the crack tip of a SLM fracture mecanics sample will be quantified as the crack grows. The influence of sample build orientation will also be examined

Presenting Author: Michael Fielden Imperial College London

Authors:

Michael Fielden Imperial College London
Catrin Mair Davies Imperial College London