Abstract: The scatter of the fatigue life of additive manufacturing specimens is quite large because of the defects dispersed in material. Due to the various defects and the large life scatter of additive manufacturing material, the relationship between life and defect characterization parameters such as defect type, defect location, and defect size are complex. This paper analyses the effect of defects on fatigue life from the perspective of statistical sense. The statistical results based on both the minimum life of the samples under the same stress level and the half of the samples with the fatigue life less than the median show that the defect size has a great influence on the fatigue life. However, the "effective area", i.e., the projection area of a defect on the plane vertical the loading direction, is not an ideal parameter to characterize the defect. In other word, the sample with the maximum defect in term of the effective area is not necessarily the shortest life sample. Fatigue life is more sensitive to the defects on surface or near-surface than those inside a specimen. There is little difference in the hazards of the two types of defects to fatigue performance, porosity defect induced failure is slightly higher than non-fusion defect induced failure.

Keywords: Additive manufacturing material, defects, defect size, defect location, fatigue life.

Biography: Prof. Liyang Xie is a professor of Mechanical Engineering at Northeastern University, Shenyang, China. He received his BS (1982) in mechanical Manufacturing, MS (1985) & PhD (1988) in structural integrity from Northeastern University, Shenyang, China. He worked one year (1996) in the Probabilistic Safety Analysis Institute, TUVE Nord, Hamburg, Germany, two years (1997-1998) in the Department of Plant Safety, Otto-von-Guericke University, Magdeburg, Germany, and three months in Karlsruhe Research Center, Karlsruhe, Germany, supported by DFG. His research interests include structural integrity, reliability and system probabilistic risk analysis. He has published more than 100 research papers in peer reviewed journals and six books. He is editorial board member of Int. J. Reliability Science and Engineering and Engineering Failure Analysis. He is the Chairman of Reliability Engineering Branch of the Chinese Society of Mechanical Engineering.