报告题目： EFFICIENT 7 and 12-PARAMETER LOCKING-FREE SHELL FINITE ELEMENTS FOR LARGE DEFORMATION ANALYSIS OF STRUCTURES
报告时间： 2019年10月17日（周四）上午10:00-11:30
报告地点： 安中大楼一楼内庭院多功能厅
报告简介：
In this lecture, shell finite elements based on seven-parameter and twelve-parameter shell theories for large deformation analysis of composite shell structures are discussed. The seven-parameter shell element is based on a modified first-order shell theory using a seven-parameter expansion of the displacement field [1-3]. The twelve-parameter shell element is developed using third-order thickness stretch kinematics [4]. Both theories require the use of fully three-dimensional constitutive equations. The virtual work statement is integrated numerically through the shell thickness at each quadrature point of the mid-surface; hence no thin-shell approximations are imposed in the numerical implementation. The finite element coefficient matrices and force vectors are evaluated numerically using appropriate high-order Gauss-Legendre quadrature rules at the appropriate quadrature points of the element mid-surface. For laminated composite shells, a user prescribed vector field (defined at the nodes) tangent to the shell mid-surface is introduced. This discrete tangent vector allows for simple construction of the local bases associated with the principal orthotropic material directions of each lamina. As a result, one is free to employ skewed and/or arbitrarily curved elements in actual finite element simulations. Through the numerical simulation of carefully chosen benchmark problems, it is shown that the developed shell elements are insensitive to all forms of numerical locking and severe geometric distortions and predict very accurate displacement and stress fields. They are the best alternative to 3-D finite elements in saving computational resources.
References
1. JN Reddy, Mechanics of Laminated Composite Plates and Shells, 2nd ed., CRC Pressi, Boca Raton, FL, 2004.
2. G.S. Payette and J.N. Reddy, Computer Methods in Applied Mechanics and Engineering. 278, 664704, 2014.
3. M.E. Gutierrez Rivera and J.N. Reddy, Mechanics Research Communications, 78, 6070, Dec 2016.
4. M.E. Gutierrez Rivera, J.N. Reddy, M. Amabili, Composite Structures, 151, 183196, Sept. 2016.
报告人简介：
J. N. Reddy教授是国际著名的应用力学家，在计算力学、复合材料力学等诸多方向做出了系列开拓性贡献。比如，在复合材料力学领域，他提出的三阶剪切变形理论被广泛应用于分析复合材料层合板壳结构，他在国际上首先系统深入地开展了功能梯度材料结构的研究。除了在科学研究上的贡献外，他在工程教育上也倾注了大量心血，撰写了十余本教材，涉及有限元计算、变分原理、板壳分析等多个主题，在国际上影响巨大。
J. N. Reddy教授于2015年当选为美国工程院院士和印度科学院外籍院士，2017年当选为加拿大工程院外籍院士和巴西工程院外籍院士。他在国际上获奖无数，代表性的有：2014年获美国土木工程师学会（ASCE）R. D. Mindlin奖，2016年获美国机械工程师学会（ASME）最高奖ASME Medal和工程科学协会（SES）William Prager奖，2018年获ASCE Theodore von Kármán奖，2019年获美国ASME Timoshenko Medal（被称为力学的诺贝尔奖）。他于2009年被葡萄牙里斯本技术大学授予荣誉学位，2011年被阿塞拜疆Odlar Yurdu University授予荣誉博士学位；自2007年起，他是中国南方科技大学名誉教授，自2018年起，他成为秘鲁Universidad Peruana de Ciencias Aplicadas名誉教授。Reddy院士乐于为学术共同体献策献力，他创办了多个学术期刊，包括Mechanics of Advanced Materials and Structures、International Journal for Computational Methods in Engineering Science and Mechanics、International Journal of Structural Stability and Dynamics，这些期刊每年发表大量高水平论文，已成为力学界的标杆旗杆。他目前还担任近30本期刊的编委，曾担任更多期刊的主编、副主编或编委。
Brief Vitae of J.N. Reddy
Dr. Reddy is a Distinguished Professor, Regents’ Professor, and inaugural holder of the Oscar S. Wyatt Endowed Chair in Mechanical Engineering at Texas A&M University, College Station, Texas. Dr. Reddy earned a Ph.D. in Engineering Mechanics in 1974 from University of Alabama in Huntsville. He worked as a Post-Doctoral Fellow in Texas Institute for Computational Mechanics (now ICES) at the University of Texas at Austin, Research Scientist for Lockheed Missiles and Space Company, Huntsville, during l974-75, and taught at the University of Oklahoma from 1975 to 1980, Virginia Polytechnic Institute & State University from 1980 to 1992, and at Texas A&M University from 1992.
Dr. Reddy, an ISI highly-cited researcher,is known for his significant contributions to the field of applied mechanics through the authorship of a large number of journal papers and 21 textbooks and the development of shear deformation plate and shell theories and their finite elements. His pioneering works on the development of shear deformation theories (that bear his name in the literature as the Reddy third-order plate theory and the Reddy layerwise theory) have had a major impact and have led to new research developments and applications. In recent years, Reddy's research has focused on the development of locking-free shell finite elements and nonlocal and non-classical continuum mechanics problems, involving couple stresses, surface stress effects, and micropolar cohesive damage.
Dr. Reddy has received numerous honors and awards. Most recent ones include: 2019 Timoshenko Medal from the American Society of Mechanical Engineers, 2018 Theodore von Karman Medal from the Engineering Mechanics Institute of the American Society of Civil Engineers, the 2017 John von Neumann Medal from the U.S. Association of Computational Mechanics, the 2016 Prager Medal, Society of Engineering Science, and 2016 ASME Medal from the American Society of Mechanical Engineers. He is a member US National Academy of Engineering and foreign fellow of Indian National Academy of Engineering, the Canadian Academy of Engineering, and the Brazilian National Academy of Engineering. In a recent world ranking of researchers in engineering, he is #13 in all of engineering and #5 in mechanical engineering.