Fatigue life prediction of additively manufactured material: Effects of surface roughness, defect size, and shape

Purpose The purpose of this paper is to obtain a more accurate fatigue life of structures by introducing the surface roughness into fatigue life prediction model. Design/methodology/approach Based on the fatigue life prediction model with surface roughness correction, the shock absorber cylinder is taken as an example to verify the feasibility of the improved method. Based on the load of the shock absorber cylinder during driving, fatigue experiments are performed under longitudinal and lateral forces, respectively. Then, the fatigue life predicted by the modified model is compared with that predicted by the traditional model. Findings By comparing with the test results, considering the influence of mean stress, the Manson method is more accurate in life prediction. Then, the modified Manson-Coffin and Manson method with surface roughness is more accurate in life prediction under longitudinal force and lateral forces, respectively. This verifies the feasibility of the improved method with the surface roughness. Originality/value The research on the influence of surface roughness on fatigue life can lay the technical foundation for the life prediction of products and have great significance to the quality evaluation of products.

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A Simple Fatigue Life Prediction Algorithm Using the Modified NASGRO Equation

Mathematical Problems in Engineering ◽

10.1155/2016/4298507 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Wei Zhang ◽

Qiang Wang ◽

Xiaoyang Li ◽

Jingjing He

Keyword(s):

Fatigue Life ◽

Fatigue Limit ◽

Life Prediction ◽

Defect Size ◽

Fatigue Life Prediction ◽

Prediction Algorithm ◽

Critical Crack ◽

Initial Defect ◽

Effective Threshold ◽

Crack Growth Model

A simple fatigue life prediction algorithm using the modified NASGRO equation is proposed in this paper. The NASGRO equation is modified by introducing the concept of intrinsic effective threshold stress intensity factor (SIF) rangeΔKeffth. One advantage of the proposed method is that the complex growth behavior analysis of small cracks can be avoided, and then the fatigue life can be calculated by directly integrating the crack growth model from the initial defect size to the critical crack size. The fatigue limit and the intrinsic effective threshold SIF rangeΔKeffthare used to calculate the initial defect size or initial flaw size. The value ofΔKeffthis determined by extrapolating the crack propagation rate curves. Instead of using the fatigue limit determined by the fatigue strength at the specific fatigue life, the fatigue limit is selected based on the horizontal tendency of theS-Ncurve. The calculated fatigue lives are compared to the experimental data of two different alloys. The predictedS-Ncurves agree with the test data well. Besides, the prediction results are compared with that calculated using the FASTRAN code. Results indicate that the proposed life prediction algorithm is simple and efficient.

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The fatigue failure analysis and fatigue life prediction model of FV520B-I as a function of surface roughness in HCF regime

Journal of Materials Research ◽

10.1557/jmr.2016.513 ◽

2017 ◽

Vol 32 (3) ◽

pp. 634-643 ◽

Cited By ~ 4

Author(s):

Jin-long Wang ◽

Yuan-liang Zhang ◽

Qing-chen Zhao ◽

Min Zhang ◽

Ze-ming Guan ◽

...

Keyword(s):

Surface Roughness ◽

Fatigue Life ◽

Prediction Model ◽

Failure Analysis ◽

Fatigue Failure ◽

Life Prediction ◽

Fatigue Life Prediction ◽

Image Position ◽

Life Prediction Model

Abstract

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Study on Fracture Mechanism and Fatigue Life Prediction for Cutting In-Situ TiB2/7050Al MMCs

Volume 12: Advanced Materials: Design, Processing, Characterization, and Applications ◽

10.1115/imece2019-10901 ◽

2019 ◽

Author(s):

Yi-feng Xiong ◽

Wen-hu Wang ◽

Kun-yang Lin ◽

Xiao-fen Liu ◽

Rui-song Jiang ◽

...

Keyword(s):

Surface Roughness ◽

Fatigue Life ◽

Prediction Model ◽

Fracture Mechanism ◽

Life Prediction ◽

Fatigue Life Prediction ◽

Matrix Composites ◽

Machined Parts ◽

Life Prediction Model

Abstract For machined parts, the surface roughness and profile would have a significant impact on the fatigue life and fracture mechanism. At present, a lot of research have been carried out on the cutting mechanism, modeling and machining performance of particle reinforced Al-based metal matrix composites. However, the study of fatigue life and fracture mechanism of machined parts after cutting particle reinforced Al-based metal matrix composites is rarely reported. In this paper, the fatigue life and fatigue fracture morphology of in-situ TiB2/7050Al MMCs were studied by high cycle fatigue test under different loading stresses. It was found that the surface roughness influenced the fatigue life greatly. With surface roughness decreasing, the fatigue life of machined parts increased exponentially. The fracture mechanism of cutting in-situ TiB2/7050Al MMCs was found to be brittle fracture due to the existence of fine particles. Besides, a fatigue life prediction model was established based on the machined surface roughness. With validation, the relative errors between prediction model and experiment were smaller than 11% indicating that the proposed fatigue life prediction model of machined in-situ TiB2/7050Al MMCs parts was of good reliability and accuracy.

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