报告题目：Modeling the mechanical properties of irradiated polycrystals by the method of VPSC
报 告 人：楚海建 教授（上海大学理学院）
报告时间：2014年9月17日 （星期三）9:30
报告地点：嘉定园区学术活动中心302室

摘要：  
　　In this study, effects of irradiation damage, crystal size and temperature on the mechanical behaviors of polycrystals are explored. By treating the spatial dependent interaction between dislocations and irradiation-induced defect as a tensorial form and taking into account the influence of dislocation source limitation at submicron, a unified size-dependent tensorial plasticity model for irradiated single crystals is developed. Based on the single crystal, a framework is built by means of VPSC (visco-plasticity self-consistent method). The feasibility and accuracy of this method are well validated by comparing numerical results with corresponding experimental data for FCC and BCC polycrystals. It is found that (1) the yield strength of unirradiated FCC copper increases with the decrease of crystal size, which is mainly attributed to the mechanism shifting from dislocation forest strengthening to dislocation source limitation strengthening. (2) For large crystal copper, the yield strength increases with the amount of irradiation, which is attributed to the increase of irradiation-induced SFTs and enhancement of dislocation-defect interaction. The phenomenon of yield dropping is observed when the irradiation is strong. (3) The competition between the irradiation effect and size effect induces the existence of a critical crystal size. Below the critical size, the yield hardening is controlled by size effect. Otherwise, it is controlled by irradiation effect. (4) The temperature effect on the mechanical property is well captured by the method. 
    Keywords: Irradiation effect; Size effect; Temperature effect; Yield stress hardening; Polycrystal

报告人简介：
    楚海建教授，博士，博士生导师，上海高校东方学者特聘教授。 2011.01~2013.01， 美国洛斯阿拉莫斯国家实验室客座研究员；2012.01~2012.06，美国康涅狄格大学工学院研究员； 2009.12~2011.01，美国阿克伦大学工学院访问学者； 2006年7月毕业于北京大学工学院，获理学博士学位；2002年7月毕业于扬州大学水利学院，获工学硕士学位；1996年7月毕业于苏州大学物理学院，获理学学士学位； 2006年获校级优秀青年骨干教师培养对象，2012年获省青蓝工程优秀中青年骨干教师称号；在国际塑性力学（IJP），JMPS，Acta　Materialia等国内外学术刊物上发表学术论文30余篇。 
　　研究领域：微纳米结构的力学性能及其优化，位错动力学与晶体塑性，复合材料力学