题目：Large Nonlinear Dynamic Responses of Shell Structures with PiezoelectricSensing and Actuating Layers
报告人：Prof. Cho Wing Solomon To（美国内布拉斯加大学林肯分校）
Over the last forty years or so, considerable research effort has been exerted on adaptive structures that based on the application of sensors and actuators. This is, perhaps, due to their useful and potential applications in aerospace, and, to a lesser extent, in shipbuilding as well as automotive engineering industries. Applications of materials such as piezoelectrics, shape memory alloys, and magnetostrictive materials have further been expanded in other fields such as robotics, highway engineering, and biomechanics. Piezoelectrics are perhaps the most widely used of these active materials due mainly to their high stiffnesses and their properties of being easily controlled through the use of applied voltage or surface charge. Compared with the use of piezoelectrics in transducer fabrications, the control of structural vibration by using distributed actuators and sensors is another important area of active research. In structural vibration control, for example, the relatively complex geometrical configurations of structural systems and nature of physical characteristics of piezoelectrics render analytical methods impossible or infeasible. Therefore, the versatile numerical approach, the finite element method (FEM) has been employed.
Since the pioneering work of Allik and Hughes (1970) many publications of linear and nonlinear analysis of structures with piezoelectric properties have been presented. Among these publications various shell finite elements with piezoelectric effects were reported. In particular, the three node triangular shell finite elements with piezoelectric effects presented by the author and his associates (2001, 2003) are good examples. The main features of these three node triangular shell elements are: (a) every node has six degrees-of-freedom (dof) and one electric potential dof, (b) hybrid strain-based formulation, (c) element mass and stiffness matrices are explicit in the sense that no numerical matrix inversion and integration are required in their derivations, and (d) two of these shell finite elements can give correctly the six rigid body modes. In the investigation being reported in this presentation, the foregoing features are expanded to include features of large nonlinear dynamic responses of finite strains and finite rotations, thickness updating, and director formulation. The latter feature is of particular importance in cases where large rotational displacements cannot be obtained by non-director formulations. In this presentation, selected computed results are included to demonstrate the aforementioned features.
Cho Wing Solomon To (杜楚荣)，工学博士，美国内布拉斯加大学林肯分校机械与材料工程学院教授。杜博士毕业于英国南安普敦大学。曾在英国南安普敦大学噪声与振动研究所、加拿大西安大略大学、加拿大卡尔加里大学等就职，现为美国内布拉斯加大学林肯分校机械与材料工程学院终身教授。
杜博士是美国机械工程师学会会士、英国诊断工程师学会创始会士、美国力学学会、美国工业与应用数学学会会员，曾是美国机械工程师学会有限元及计算技术委员会主席、国际力学期刊，应用与理论力学学报的副主编。工程动力学与振动 eBook Series主编。主要研究领域包括噪声与振动、固体和计算力学、系统动力学及控制等，特别是非线性、随机及混沌振动，机械结构噪声与振动控制，信号分析及机械噪声诊断，线性及非线性有限元方法及应用等。出版有《Introduction to Dynamics and Control in Mechanical Engineering Systems》, 2016, ASME and Wiley;《Stochastic Structural Dynamics: Application of Finite Element Methods》, 2014,Wiley; 《Nonlinear Random Vibration: Analytical Techniques and Applications, 2nd Edition》, 2012, Taylor and Francis;《Nonlinear Random Vibration: Computational Methods》, 2010, Zip Publishing等多部著作。