报告人：胥柏香(Bai-Xiang Xu)  教授

Mechanics of Functional Materials, Institute of Materials Science

     德国 达姆施塔特工业大学

              Email: xu@mfm.tu-darmstadt.de,

              http://www.mawi.tu-darmstadt.de/mfm

时  间：2019年5月30日（星期四）上午10:00-11:00

地  点：北京大学工学院一号楼212会议室

主持人：易新   特聘研究员

报告内容简介:  There exists large potential for the mechanical and functional property of the additively manufactured part to be optimized with respect to the process and material parameters. Compared with the expensive trial-and-error principle, physical models and numerical simulations are much more efficient in terms of both cost and time. They allow massive parameter studies which can provide large database for statistical analysis such as machine learning to extract the process-microstructure-property relation. One needs hence a reliable physical model, which can recapture the processing and the microstructure development. 

    In this work we present a thermodynamically consistent phase-field model and the finite element simulations of microstructure evolution (pore and grain structure) during powder bed fusion additive manufacturing of metallic materials. Preliminary work has been done on the particle level and the mesoscopic level. Furthermore, we study both the selective laser sintering (SLS) and selective laser melting (SLM). The model includes simultaneously complex underlying physics, such as extreme heat diffusion, melting, solidification and grain coalescence. The models are parameterized using measured thermodynamic and kinetic data. For the process simulation, we overcome the numerical challenges on powder bed deposition, power injection and strategies to reduce the computation cost by a novel algorithm analogy to minimum coloring problem and grain tracking approach. Simulation results will be shown for e.g. stainless steel 316L and Fe-alloys. We reveal the influences of process parameters e.g. the laser power and scan speed on the microstructure features, such as porosity, surface morphology, geometric variation of grains and densification. The simulation results will be discussed in comparison with the experimental data available in the literature. Moreover, through micromechanics tools, the effective mechanical properties of the simulated microstructure will be evaluated.

报告人简介: 胥柏香教授，2002年获得南京河海大学学士学位，2008年获得北京大学博士学位，同年获得德国洪堡奖学金。2016年获得德国达姆斯塔特工学大学材料科学系终身教授。近期研究课题着重于功能及能源材料的多场耦合问题的理论建模及数值模拟，成型/微结构/性能之间的关联性的研究，主要涉及纳米及微米尺度。近五年主持或参与科研项目12项（欧洲项目1项、德国联邦政府项目9项，德国黑森州项目2项）。近五年在Nature Communications, Materials Horizons, Nano Energy，Acta Materialia，Int. J. Plasticity, IJSS等重要国际期刊上发表SCI论文60余篇。

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