报告题目：

Prediction of fracture toughness of ceramic composites as function of microstructure

 报告人:                Prof. Min Zhou

The George W. Woodruff School of Mechanical Engineering,

School of Materials Science and Engineering

Georgia Institute of Technology, Atlanta, GA 30332-040, USA

时间：2015年3月18日(周三)  9: 30     

地点：中国科学院力学研究所主楼344会议

报告摘要：

Lower-scale structures determine the macro-scale fracture toughness of materials through the activation of different fracture and dissipation mechanisms. To tailor the fracture toughness through microstructure design, it is important to establish relations between microstructure and fracture toughness. To this end, systematic characterization of microstructures, explicit tracking of crack propagation process and realistic representation of deformation and fracture at different length scales are required. We present a cohesive finite element methods (CFEM) based multi-scale framework for predicting the fracture toughness of brittle materials such as ceramic composites and ductile materials such as alloys as a function of microstructure and basic material attributes. The framework does not involve curve fitting and accounts for the effects of microstructural heterogeneity, phase morphology, constituent behavior and interfacial bonding between constituents in materials. The approach uses the J-integral to calculate the initiation/propagation fracture toughness, allowing explicit representation of realistic microstructures and fundamental fracture mechanisms. Based on the CFEM results, a semi-empirical model is developed to provide a quantitative relation between the propagation toughness and statistical measures of microstructure, fracture mechanisms, and constituent and interfacial properties. The model provides deeper insights into the fracture process as it quantitatively predicts the proportion of each fracture mechanism in the heterogeneous microstructures. For example, to enhance the fracture toughness of two-phase ceramic composites, fine microstructure size scale, rounded reinforcement morphology and appropriately weak bonding strength should be introduced to promote interface debonding and discourage particle cracking. Another insight is that there are optimal levels of interfacial stiffness/toughness that maximize the fracture toughness. The relations and conclusions can be used in the selection of materials and the design of new materials with tailored properties.

报告人简介：

Min Zhou is George W. Woodruff Professor of Mechanical Engineering and Materials Science and Engineering at Georgia Tech. He received his Ph.D. from Brown University in 1993 and was a postdoctoral fellow at Caltech between 1993 and 1995. He joined the faculty at Georgia Tech in 1995. His research focuses on material behavior at several length scales, emphasizing molecular dynamics simulations, multiscale continuum modeling, and experiments with laser interferometry and digital diagnostics. Dr. Zhou is a recipient of the US National Science Foundation (NSF) CAREER award and Sigma Xi Society Georgia Chapter Best Paper Award. He is also a Fellow of the American Society for Mechanical Engineers (ASME).

报告联系人：沈楠  (office@lnm.imech.ac.cn 82543935)