题 目1：Recent Developments in Plasticity and Ductile Fracture Modeling
报告人1：Xiaosheng Gao
时 间：2016年7月4日上午9:30
题 目2：工程结构材料损伤数字仿真
报告人2：吕胜利
时 间：2016年7月4日上午11:00
地 点：实验2号楼625会议室（土木与交通工程学院工程力学研究所）
Biography of Xiaosheng Gao：
EDUCATION
Ph.D., Mechanical Engineering, Brown University, May 1998
Major: Solid Mechanics; Minors: Materials Science & Applied Mathematics
Thesis: Numerical Modeling of Crack Growth in the Ductile / Brittle Transition Regime
M.S., Applied Mathematics, Brown University, May 1995
M.S., Solid Mechanics, Xi’an Jiaotong University (China), June 1990
Thesis: A Study of Mode I Fracture in Functionally Graded Materials
B.S., Engineering Mechanics, Xi’an Jiaotong University (China), July 1987
AREAS OF SPECIALIZATION
Mechanics of materials and structures; Constitutive modeling of advanced materials;
Computational mechanics; Fatigue and fracture mechanics; Micromechanics; Multi-scale
modeling of damage & failure and material characterization with microstructure
PROFESSIONAL EXPERIENCE
Professor, The University of Akron, 2011 – present
Associate Chair for Graduate Programs, Department of Mechanical Engineering, since Aug. 2013
Office of Naval Research (ONR) Summer Faculty Fellow, summer 2006 & 2007
Associate professor, The University of Akron, Aug. 2006 – May 2011
Visiting professor, National University of Singapore, summer 2005
Assistant professor, The University of Akron, Jan. 2001 – May 2006
Postdoctoral researcher, University of Illinois at Urbana-Champaign, Sept. 1997 – Dec. 2000
Visiting scholar, Royal Institute of Technology (Sweden), Nov. 1996 – May 1997
Graduate research assistant, Brown University, Sept. 1992 – Aug. 1997
Assistant professor, Northwestern Polytechnical University (China), June 1990 – Aug. 1992
AWARDS & HONORS
Office of Naval Research (ONR) Young Investigator Award, 2002
Elected as a Fellow of the American Society of Mechanical Engineers (ASME), June 2013
摘要：
This talk summarizes recent developments in modeling plasticity and ductile fracture behavior of metallic structural materials at engineering scales, with emphasis on the effect of the stress state. Increasing experimental evidences have shown that many engineering materials exhibit the strength differential effect and their plastic response cannot be described by the classicalJ2plasticity theory. Analysis of experimental data obtained from a variety of structural alloys result in a general form of plasticity model for isotropic materials, where the yield function and the flow potential are expressed as functions of the first invariant of the stress tensor and the second and third invariants of the deviatoric stress tensor. For anisotropic materials, a method based on the linear transformation of the stress deviator is shown to be effective in formulating the yield function and the flow potential. Stress state also has strong effect on ductile fracture. It is shown that the material failure process is not only influenced by the stress triaxiality but also by the Lode parameter. Consequently a cumulative strain damage model, where the damage parameter depends on the stress triaxiality and the Lode parameter, is developed. Another approach to model ductile fracture is to use porous material models as void nucleation, growth and coalescence represents a major failure mechanism. Recent modifications to the Gurson-type porous material models to include the Lode angle effect and the shear damage contribution have extended the capability of the models to predict damage and fracture under low (even negative) triaxiality conditions. Numerical models combining these newly developedplasticity and ductile damage models have shown great promising for integrity and reliability assessment of engineering components. The predictive power of these models are demonstrated through extensive experimental and numerical studies of various specimens experiencing a wide range of stress states.
吕胜利简历：
西北工业大学无人机重点实验室,研究员，博士生导师，1987年在西北工业大学获得工程力学专业学士学位，1990年在西安交通获得固体力学专业硕士学位，1999年在西北工业大学获得固体力学专业博士学位。近年来主要从事飞机结构的腐蚀与疲劳、新型轻质复合材料结构设计与数字仿真技术、材料科学数据库设计与虚拟现实技术研究。在国内外核心刊物发表论文100多篇，SCI、EI收录20多篇，出版专著2部，获省部级壹等奖1项，主持国家科技支撑计划、973、总装预研基金、航空基金、航天科技创新基金、中石油创新基金等科研项目。
摘要：
介绍重大工程结构损伤仿真试验系统，建立工程结构材料各种服役环境和载荷的数字化模型，实现工程结构材料服役环境的真实模拟与再现，为工程结构材料损伤及失效过程的数字仿真试验提供基础。然后针对飞机、风电等海洋产业的部件耐腐需求，从飞机铝合金结构海洋环境腐蚀形貌表征、图像特征提取及三维建模仿真等方面介绍我们的具体研究工作，最后介绍我们利用海洋腐蚀损伤和寿命预测方面的基础研究成果，研发得海洋腐蚀数据库与数字仿真系统，建立的数据共享网站（www.dematers.com)。
