題目：Large Nonlinear Dynamic Responses of Shell Structures with PiezoelectricSensing and Actuating Layers

報告人：Prof. Cho Wing Solomon To（美國內布拉斯加大學林肯分校）

時間：2017年7月11日（周二）下午14：00-15：30

地點：明故宮校區A18-529

主辦單位：國際合作處、科協、航空宇航學院、機械結構力學及控制國家重點實驗室、

報告摘要：

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.

報告人簡介：

Cho Wing Solomon To (杜楚榮)，工學博士，美國內布拉斯加大學林肯分校機械與材料工程學院教授。杜博士畢業于英國南安普敦大學。曾在英國南安普敦大學噪聲與振動研究所、加拿大西安大略大學、加拿大卡爾加里大學等就職，現為美國內布拉斯加大學林肯分校機械與材料工程學院終身教授。

杜博士是美國機械工程師學會會士、英國診斷工程師學會創始會士、美國力學學會、美國工業與應用數學學會會員，曾是美國機械工程師學會有限元及計算技術委員會主席、國際力學期刊，應用與理論力學學報的副主編。工程動力學與振動 eBook Series主編。主要研究領域包括噪聲與振動、固體和計算力學、系統動力學及控制等，特別是非線性、隨機及混沌振動，機械結構噪聲與振動控制，信號分析及機械噪聲診斷，線性及非線性有限元方法及應用等。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。