报告题目：Experimental and numerical investigation of laser shock peening regarding residual stresses and fatigue
报告人：Benjamin Klusemann 教授，德国亥姆霍兹-吉斯达赫特国家研究中心
联系人：王 敏 教授
Benjamin Klusemann studied mechanical engineering at the TU Dortmund, Germany where he spend also one semester at the University of Idaho, USA as exchange student. He did his PhD in computational mechanics under the supervision of Bob Svendsen at TU Dortmund, Germany, graduating in 2010 followed by a postdoctoral period at the RWTH Aachen, Germany. In 2012, he moved to the TU Hamburg, Germany to join the institute of continuum mechanics and material mechanics as senior researcher. With a Humboldt fellowship, he joint the California Institute of Technology, USA as postdoctoral scholar in 2013. Since October 2015, he is professor for local engineering, in particular process simulation at the Leuphana University of Lüneburg. Currently he is head of the working group “Residual stress engineering” at the Helmholtz-Zentrum Geesthacht as well. He received a number of awards, including the dissertation award 2011 of the TU Dortmund, the teaching award 2016 of Leuphana University of Lüneburg and the Richard-von-Mises-Prize of GAMM 2017. His research interests include various topics in the field of joining and modification techniques, micromechanics and multi-scale modeling, crystal plasticity and further numerical methods, in particular in terms of experimental-modeling correlations.
Laser shock peening (LSP) is an innovative surface treatment technique that is applied to modify the local properties to improve for example the overall fatigue performance of metallic structures. The peening locally generates deep compressive stresses, which retard or even suppress crack initiation and growth. Arranging the shots in an optimal design, a significant improved fatigue behavior can be observed. As LSP includes a number of process parameters, a purely experimental based optimization of LSP is a time consuming task. In this regard, statistical or numerical approaches can significant help to understand and systematically analyze the effect of LSP. In this work a combined experimental-numerical study on the residual stress distribution and the resulting fatigue crack propagation in aluminum alloys is presented. A multi-stage simulation strategy will be presented. This involves an LSP-process simulation to predict the plastic deformations, a transfer approach based on the eigenstrain-method to include the plastic deformations in a finite element (FE) model of a C(T)-specimen as well as a FE-simulation of the C(T)-specimen to predict the residual stresses and the stress concentration for different external loads. Based on these information, the FCP rate is finally determined via different empirical FCP-equations. The FE-model of the CT-specimen is also applied to study the mechanisms at the crack tip (e.g. crack closure effects) and the redistribution of the residual stresses caused by the crack growth. The application of LSP to a larger specimen will be shown.