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Guided wave propagation in multilayered piezoelectric structures

Science china(Physics,mechanics & Astronomy) 2009年第7期52卷 1094-1104页

作者： GUO YongQiang1, CHEN WeiQiu2.3 & ZHANG YongLiang4 1 Key Laboratory of mechanics on Disaster and Environment in Western china, Ministry of Education, and School of Civil {2. and mechanics, Lanzhou university, Lanzhou 730000, china 2.Key Laboratory of Soft Soils and Geoenvironmental {2., Ministry of Education, and department of Civil {2., zhejiang university, Hangzhou 310058, china 3 department of engineering mechanics, zhejiang university, Hangzhou 31002., china 4 School of Civil {2., Lanzhou Jiaotong university, Lanzhou 730070, china Key Laboratory of mechanics on Disaster and Environment in Western china Ministry of Education and School of Civil Engineering and Mechanics Lanzhou University Lanzhou 730000 China Key Laboratory of Soft Soils and Geoenvironmental engineering Ministry of Education and Department of Civil Engineering Zhejiang University Hangzhou 310058 China department of engineering {2. Zhejiang University Hangzhou 310027 China School of Civil engineering Lanzhou Jiaotong University Lanzhou 730070 China

A general formulation of the method of the reverberation-ray matrix (MRRM) based on the state space formalism and plane wave expansion technique is presented for the analysis of guided waves in multilayered piezoelectric structures. Each layer of the structure is made of an arbitrarily anisotropic piezoelectric material. Since the state equation of each layer is derived from the three-dimensional theory of linear piezoelectricity, all wave modes are included in the formulation. Within the framework of the MRRM, the phase relation is properly established by excluding exponentially growing functions, while the scattering relation is also appropriately set up by avoiding matrix inversion operation. Consequently, the present MRRM is unconditionally numerically stable and free from computational limitations to the total number of layers, the thickness of individual layers, and the frequency range. Numerical examples are given to illustrate the good performance of the proposed formulation for the analysis of the dispersion characteristic of waves in layered piezoelectric structures.

关键词： multilayered piezoelectric structures the method of reverberation-ray matrix guided waves dispersion characteristic

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Analytical solution and semi-analytical solution for anisotropic functionally graded beam subject to arbitrary loading

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Science china(Physics,mechanics & Astronomy) 2009年第8期52卷 1244-1256页

作者： HUANG DeJin1,2.DING HaoJiang1 & CHEN WeiQiu3 1 Key Laboratory of Soft Soils and Geoenvironmental engineering,Ministry of Education,zhejiang university,Hangzhou {2.,china 2.Faculty of engineering,Ningbo university,Ningbo 3152.1,china 3 department of engineering mechanics,zhejiang university,Hangzhou {2.,china Key Laboratory of Soft Soils and Geoenvironmental engineering Ministry of Education Zhejiang University Hangzhou 310027 China Faculty of engineering Ningbo University Ningbo 315211 China department of engineering {2. Zhejiang University Hangzhou 310027 China

Analytical and semi-analytical solutions are presented for anisotropic functionally graded beams subject to an arbitrary load,which can be expanded in terms of sinusoidal *** plane stress problems,the stress function is assumed to consist of two parts,one being a product of a trigonometric function of the longitudinal coordinate(x) and an undetermined function of the thickness coordinate(y),and the other a linear polynomial of x with unknown coefficients depending on *** governing equations satisfied by these y-dependent functions are *** expressions for stresses,resultant forces and displacements are then deduced,with integral constants determinable from the boundary *** the analytical solution is derived for the beam with material coefficients varying exponentially or in a power law along the thickness,the semi-analytical solution is sought by making use of the sub-layer approximation for the beam with an arbitrary variation of material parameters along the *** present analysis is applicable to beams with various boundary conditions at the two *** numerical examples are presented for validation of the theory and illustration of the effects of certain parameters.

关键词： anisotropic material functionally graded arbitrary loading stress function analytical solution semi-analytical solution

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Analysis on cohesive crack opening displacement considering the strain softening effect

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Science china(Physics,mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1, XU Shilang2.& ZHAO Xiqiang3 1. mechanics department, Shandong {2. of Technology, Zibo 2.5049, china 2. Civil engineering department, Dalian {2. of Technology, Dalian 11602., china 3. Mathematics department, Ocean {2. of china, Qingdao 2.6071, china mechanics department Shandong University of Technology Zibo 255049 China Civil engineering department Dalian University of Technology Dalian 116024 China Mathematics department Ocean University of China Qingdao 266071 China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

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A low frequency piezoelectric power harvester using a spiral-shaped bimorph

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Science china(Physics,mechanics & Astronomy) 2006年第6期49卷 649-659页

作者： HU Yuantai1,2.HU Hongping2.& YANG Jiashi3 1. Institute of mechanics and Sensing Technology,Central South university,Changsha 410083,{2. 2. department of mechanics,Huazhong university of Science and Technology,Wuhan 430074,{2. 3. department of engineering mechanics,university of Nebraska,Lincoln,NE 68588-052.,USA 1. Institute of mechanics and Sensing Technology Central South University Changsha 410083 China 2. department of mechanics Huazhong University of Science and Technology Wuhan 430074 China 3. department of engineering {2. University of Nebraska Lincoln NE 68588-0526 USA

We propose a spiral-shaped piezoelectric bimorph power harvester operating with coupled flexural and extensional vibration modes for applications to low frequency energy sources. A theoretical analysis is performed and the computational results show that the spiral structure has relatively low operating frequency compared to beam power harvesters of the same size. It is found that to optimize the performance of a piezoelectric spiral-shaped harvester careful design is needed.

关键词： spiral-shaped bimorph,piezoelectric harvester,power density.

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Modeling of multi-inclusion composites with interfacial imperfections:Micromechanical and numerical simulations

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Science china(Technological Sciences) 2010年第3期53卷 720-730页

作者： CHEN WeiQiu 1,ZHU XingYi 2.&HUANG ZhiYi 2.1 department of engineering {2.,Yuquan Campus,zhejiang university,Hangzhou 31002.,china 2.Key Laboratory of Soft Soils and Geoenvironmental engineering,Ministry of Education department of Civil engineering,Zijingang Campus,zhejiang university,Hangzhou 310058,china 1. department of engineering {2. Yuquan Campus Zhejiang University Hangzhou 310027 China2. Key Laboratory of Soft Soils and Geoenvironmental Engineering Ministry of Education Hangzhou 310058 China3. Department of Civil Engineering Zijingang Campus Zhejiang University Hangzhou 310058 China

A micromechanical approach based on a two-layer built-in model and a numerical simulation based on boundary element method are proposed to predict the effective properties of the multi-inclusion composite with imperfect *** spring model is introduced to simulate the interface *** two methods are compared with each other,and good agreement is *** effects of interface spring stiffness,volume ratio and stiffness of inclusions on the micro-and macro-mechanical behaviors of fiber-reinforced composites are *** is shown that the developed micromechanical method is very comprehensive and efficient for fast prediction of effective properties of composites,while the numerical method is very accurate in detailed modeling of the mechanical behavior of composites with multiple inclusions.

关键词： micromechanics boundary element method interface multi-inclusion composite effective elastic property

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Noether-type theory for discrete mechanico-electrical dynamical systems with nonregular lattices

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Science china(Physics,mechanics & Astronomy) 2010年第9期53卷 1687-1698页

作者： FU JingLi1,CHEN LiQun2.& CHEN BenYong3 1 Institute of Mathematical Physics,zhejiang Sci-Tech university,Hangzhou 310018,{2. 2.department of mechanics,Shanghai university,Shanghai 2.0072.{2. 3 Faculty of Mechanical-engineering & Automation,zhejiang Sci-Tech university,Hangzhou 310018,{2. 1. Institute of Mathematical Physics Zhejiang Sci-Tech University Hangzhou 310018 China2. Department of Mechanics Shanghai University Shanghai 200072 China3. Faculty of Mechanical-Engineering & Automation Zhejiang Sci-Tech University Hangzhou 310018 China

We investigate Noether symmetries and conservation laws of the discrete mechanico-electrical systems with nonregular *** operators of discrete transformation and discrete differentiation to the right and left are introduced for the *** on the invariance of discrete Hamilton action on nonregular lattices of the systems with the dissipation forces under the infinitesimal transformations with respect to the time,generalized coordinates and generalized charge quantities,we work out the discrete analog of the generalized variational *** this formula we derive the discrete analog of generalized Noether-type identity,and then we present the generalized quasi-extremal equations and properties of these equations for the *** also obtain the discrete analog of Noether-type conserved laws and the discrete analog of generalized Noether theorems for the *** we use an example to illustrate these results.

关键词： Noether symmetry variational formula quasi-extremal equation conservation law discrete mechanico-electrical dynamical system

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Two-dimensional thermoelasticity solution for functionally graded thick beams

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Science china(Physics,mechanics & Astronomy) 2006年第4期49卷 451-460页

作者： Lü Chaofeng1, CHEN Weiqiu1 & ZHONG Zheng2.1. department of Civil engineering, {2., Hangzhou 31002., china 2. Key Laboratory of Solid mechanics of Ministry of Education, School of Aerospace engineering and Ap- plied mechanics, Tongji university, Shanghai 2.0092. china department of Civil engineering Zhejiang University Hangzhou 310027 China Key Laboratory of Solid mechanics of Ministry of Education School of Aerospace Engineering Applied mechanics Tongji University Shanghai 200092 China

Two-dimensional thermoelasticity analysis of functionally graded thick beams is presented using the state space method coupled with the technique of differential quadrature. Material properties vary continuously and smoothly through the beam thickness, leading to variable coefficients in the state equation derived from the elasticity equations. Approximate laminate model is employed to translate the state equation into the one with constant coefficients in each layer. To avoid numerical instability, joint coupling matrices are introduced according to the continuity conditions at interfaces in the approximate model. The differential quadrature procedure is applied to discretizing the beam in the axial direction to make easy the treatment of arbitrary end conditions. A simply-supported beam with exponentially varying material properties is considered to validate the present method. Numerical examples are performed to investigate the influences of relative parameters.

关键词： state equation differential quadrature approximate laminate model joint coupling matrices thermal stresses.

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Electro-mechanical response of functionally graded beams with imperfectly integrated surface piezoelectric layers

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Science china(Physics,mechanics & Astronomy) 2006年第5期49卷 513-525页

作者： YAN Wei1 & CHEN Weiqiu1,2.1. department of Civil engineering, {2., Hangzhou 31002., china 2. State Key Lab of CAD & CG, {2., Hangzhou 31002., china 1. department of Civil engineering Zhejiang University Hangzhou 310027 China 2. State Key Lab of CAD & CG Zhejiang University Hangzhou 310027 China

The time-dependent behavior of a simply-supported functionally graded beam bonded with piezoelectric sensors and actuators is studied using the state-space method. The creep behavior of bonding adhesives between piezoelectric layers and beam is characterized by a Kelvin-Voigt viscoelastic model, which is practical in a high temperature circumstance. Both the host elastic functionally graded beam and the piezoelectric layers are orthotropic and in a state of plane stress, with the former being inhomogeneous along the thickness direction. A laminate model is employed to approximate the host beam. Moreover, the coupling effect between the elastic deformation and electric field in piezoelectric layers is considered. Results indicate that the viscoelastic property of interfacial adhesives has a significant effect on the function of bonded actuators and sensors with time elapsing.

关键词： functionally graded beam piezoelectric layers Kelvin-Voigt model state-space method

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Dynamic behavior of polymer surface and the time dependence of contact angle

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Science china Chemistry 2005年第6期48卷 553-559页

作者： WANG Xinping1, CHEN Zhifang1 & SHEN Zhiquan2.1. Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Education Ministry, department of Applied Chemistry, zhejiang Institute of Science and Technology, Hangzhou 310033, {2. 2. department of Polymer Science and engineering, zhejiang university, Hangzhou 31002., {2. 1. department of Applied Chemistry Zhejiang Institute of Science and Technology Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Education Ministry 310033 Hangzhou China 2. department of Polymer Science and engineering Zhejiang University 310027 Hangzhou China

Time-dependent contact angles were measured by depositing sessile drops of wa-ter on the polymer surfaces and monitoring the drop shape as a function of time. It was found that contact angles decreased sharply with contact time and the equilibrium contact angle was finally attained after a certain time. Values of starting (θ s) and equilibrium contact angles (θ e) obtained by the sessile drop method depend on polymer properties. The Wilhelmy plate technique was used to measure advancing and receding contact angles. The variations of starting (θ s) and equilibrium contact angles (θ e), advancing (θ a) and receding contact angles (θ r) have been studied on the oxidized surface of polymers containing polybutadiene block to explore the cause of time-dependence in contact angle measurement and the meaning of θ s and θ e. The results showed the linear relationships between starting (θ s) and advancing contact angles (θ a), the equilibrium (θ e) and receding contact angles (θ r). The similar relationship was also established between the contact angle hysteresis (θ a?θ r) and differences (θ s ?θ e) in starting contact angles and equilibrium contact angles. Therefore, time-dependence in contact angle measurement was mainly attributed to the surface reconstruction when water drops were deposited on polymer surfaces. The starting contact angle was contributed by the hydrophobic component on polymer surface and the equilibrium contact angle mainly by the hydrophilic component of polymer. These results not only demonstrated the interdependency between two contact angle measurements, the sessile drop method and the Wilhelmy plate technique, but also provided the experimental evidence to explain the cause of time-dependent contact angle. This may also provide a new method to study dynamic behavior of polymer surface.

关键词： contact angle, surface dynamic behavior, polymer surface, dynamic contact angle, time-dependence.

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A theoretical model of turbulent fiber suspension and its application to the channel flow

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Science china(Physics,mechanics & Astronomy) 2010年第9期53卷 1659-1670页

作者： LIN JianZhong1,2.& SHEN SuHua1 1 department of mechanics,{2.,Hangzhou 31002.,china 2.china Jiliang university,Hangzhou 310018,china 1. department of mechanics Zhejiang University Hangzhou 310027 China2. China Jiliang University Hangzhou 310018 China

A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of *** order to close the above equations,the equation of probability distribution function for mean fiber orientation is also *** theoretical model is applied to the turbulent channel flow and the corresponding equations are solved *** numerical results are verified by comparisons with the experimental *** effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are *** on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.

关键词： theoretical model turbulent fiber suspension numerical simulation channel flow modification of velocity profile

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