新闻中心


美国德州农工大学J.N.Reddy教授莅临我院做学术报告
2019-10-24 胡健英 

美国德州农工大学J.N.Reddy教授莅临我院做学术报告

 

美国工程院院士德州农工大学J.N.Reddy教授20191015日星期二来机械工程与力学学院开展学术访问和交流活动,并为学院教师和学生做了题为“Robust, Locking-Free Shell Finite Elements for Large Deformation Analysis of Structures”的学术报告。

报告会上,Reddy教授描述了基于七参数和十二参数壳层理论的复合壳结构大变形分析的壳层有限元方法。七参数壳单元是基于改进的利用位移场七参数展开的一阶壳理论;十二参数壳单元则是建立在三阶厚度伸长动力学之上。他耐心地讲解了虚拟功的表达式是如何通过中表面每一个交点的壳层厚度进行数值积分的。采用适当的高阶高斯-勒让德求积规则,可以对有限元系数矩阵和力矢量进行了数值计算。对于复合材料层合壳,他表示通过用户指定的与壳中表面相切的向量场(在节点处定义),可以在实际的有限元模拟中自由地使用倾斜和/或任意弯曲的元素。最后,通过对精心选择的基准问题的数值模拟,他展示了所开发的壳单元对所有形式的数值锁定和严重的几何畸变都不敏感,可以非常有效地预测位移和应力场。Reddy教授表明必须采用强健的计算工具来推进力学问题的理论发展和数值计算。Reddy教授的报告吸引了学院的很多师生前来参加,报告厅里座无虚席,与会教师和学生与他在报告会上互动频繁,Reddy老师对所提疑问一一作了解答。

会后Reddy教授还与学院青年教师就计算力学问题展开进一步的讨论。Reddy教授亲切的回答与会青年学者提出的问题,甚至现场直接耐心细致地进行公式推导。与会青年学者皆被Reddy教授扎实深厚的力学功底所折服,为其持之以恒、笔耕不辍的科研态度所感动。Reddy教授就我们一些老师提出的问题进行了深入解答,也表示会在一些问题上开展合作研究。

Reddy教授以其在应用力学领域的重要贡献而闻名,是ISI上高被引的研究人员。他撰写了大量的期刊论文和21本教科书,开发了剪切变形板壳理论及其有限元方法。他在剪切变形理论发展方面的开创性著作(以他的名字命名的Reddy三阶板理论和Reddy分层理论)产生了重大影响,促进了新的研究发展和应用。近年来,Reddy教授的研究主要集中在非自锁壳有限元和非局部、非经典连续介质力学问题的发展上,涉及到耦合应力、表面应力效应和微极性内聚损伤。雷迪博士获得过无数荣誉和奖项,其中包括2019年美国机械工程师协会颁发的应用力学界最高奖项Timoshenko Medal,2018年美国土木工程师协会工程力学研究所颁发的Theodore von Karman Medal,2017年美国计算力学协会颁发的John von Neumann Medal,2016年工程科学学会颁发的Prager Medal,2016年从美国机械工程师学会ASME奖章。他是美国工程院院士,印度国家工程院、加拿大工程院和巴西国家工程院外籍院士。在最近的世界工程研究人员排名中,他在所有工程科研人员中排名第13,在机械工程中排名第5

 

Prof. J.N. Reddy Delivered a Talk in His Visit

 

Prof. J.N. Reddy, Texas A&M University, College Station, and a member of the US National Academy of Engineering, presented a talk entitled "Robust, Locking-Free Shell Finite Elements for Large Deformation Analysis of Structures" to a broad audience of faculty and students on Oct. 15, 2019 in Ningbo University.

In his presentation, Prof. Reddy described shell finite elements based on seven-parameter and twelve-parameter shell theories for large deformation analysis of composite shell structures. The seven-parameter shell element is based on a modified first-order shell theory using a seven-parameter expansion of the displacement field. The twelve-parameter shell element is developed using third-order thickness stretch kinematics. He patiently derived how the virtual work statement is integrated numerically through the shell thickness at each quadrature point of the mid-surface. 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, he introduced a user prescribed vector field (defined at the nodes) tangent to the shell mid-surface, thus exhibiting that the user is free to employ skewed and/or arbitrarily curved elements in actual finite element simulations. At last, through the numerical simulation of carefully chosen benchmark problems, he showed 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. Prof. Reddy's lecture attracted many teachers and students. Prof. Reddy concluded that we must develop robust computational tools that make use of advances made in theoretical developments and numerical methods.

Prof. Reddy's talk attracted a lot of faculty and students. Participants attended the lecture interacted with him frequently in the lecture, and Prof. Reddy answered questions one by one.

After the meeting, Prof. Reddy also had a further discussion with the young professors on computational mechanics. Prof. Reddy kindly answered the questions raised by the young scholars, and even patiently deduced the formula on the spot. The young scholars were all impressed by Prof. Reddy's wide mechanical knowledge and touched by his persistent and tireless attitude towards scientific research.  There were discussions on collaborative research with faculty members of Ningbo University with topics raised during the talk and meeting.

Prof. Reddy is an ISI highly-cited researcher, 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.

 

上一条:王骥教授在国际会议ICMRA 2019做大会报告
下一条:第三届全国热应力大会第二轮征文通知
关闭窗口

更多消息请联系:

宁波大学压电器件技术实验室

联系人:王丽琳
联系电话:0574-8760 0467
E-mail:wanglilin@nbu.edu.cn

网站:http://piezo.nbu.edu.cn/

Powered by 压电器件技术重点实验室

管理登陆