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In the present paper, the interfacial crack growth of fibre reinforced composites under tension–tension cyclic load was simulated through the secondary development of the commercial finite element package ANSYS. For the importance of frictional degradation on the debonded interface during fatigue process, the modified power degradation model proposed in the authors' previous work is introduced into the present finite element analysis. Energy release rates rather than stress intensity factors are calculated in terms of difference approximation and utilized in Paris formula. Both looping cyclic load, calculating energy release rate, defining debond criterion and crack propagation law; updating parameters are programmed in ANSYS parametric design language, and the relationships between the parameters (such as the damage factor) and the number of cycles are obtained; the non-uniform stiffness degradation of matrix is taken into account. The numerical results are compared and discussed with the analytical solutions and good agreement is found. At the same time, a comparison between the present investigation and an experiment study is addressed.

By the secondary development of a commercial finite element package, the present study simulates the simultaneous growth of interfacial debonding and matrix annular crack surrounding fiber of fiber reinforced composites under tension—tension cyclic load. Energy release rates are utilized in the Paris law to avoid concerning the singularity of crack tips. With the combination of finite element method and difference approximation, the authors program the degradation model of coefficient of friction, debond criterion, propagation law and loop of load process, and then the relationships between the parameters (such as the crack length and debond length) and number of cyclic load are obtained and discussed. The numerical results show that interaction of growth of two cracks plays an important role in fatigue damage of fiber reinforced composites.

By secondary development of the commercial finite element package ANSYS, the present work characterizes the bi-interfacial debonding (fiber/coating and coating/matrix) behavior of coated fiber reinforced composites under tension–tension cyclic load. In the finite element analysis of the double shear-lag model, ordinary mesh and the relationship between stress intensity factor and energy release rate are utilized in order to avoid concerning the singularity of crack tips. Based on the results of strain energy, the debond growth in one cycle is derived from the combined implementation of difference approximation; defining debond criterion and crack propagation law by programming. With the simulation of total fatigue life, the effects of strength and thickness of coating materials on the bi-interfacial crack growth are studied, and two-interface coupling in debonding is found. Furthermore, non-uniform damage of coating materials and other fatigue properties are also discussed.

The aim of this paper is to simulate the rebar/concrete interface debonding of FRP strengthened RC beams under fatigue load and also, to ascertain the influence of design parameters such as the elastic modulus, thickness and length of the FRP plate on the debonding performance. In order to simplify the simulation, some basic equilibrium equations are formulated and then the stresses of the rebar and FRP plate are numerically solved, and stress intensity factor is avoided in the simulation by fundamentals of fracture mechanics because of its complexity around the crack tip of bi-material interface. With the combination of finite element method and difference approximation, authors program the degradation model of coefficient of friction, debond criterion, propagation law and loop of load process into a commercial finite element code to investigate the fatigue debonding. The relationships between the debond length as well as other fatigue parameters and number of cyclic load are obtained and discussed.

Taking the bonding layers and electrodes into account, the multi-layered piezoelectric cantilevers are studied based on the theory of elasticity. Different from the traditional investigations based on the elementary theory of elasticity, the Airy stress function method is used in the present paper. The stress function and induction function are proposed and determined, and then the exact solutions of the static governing equations are found. The material properties and thickness of different layers may be different in the present investigations. As two special cases, the exact static solutions for both unimorph and bimorph are directly obtained by using the present general solutions. The exact solutions obtained in the present paper are compared with the numerical results and others’ investigations, and good agreements are found. In addition, the effects of the properties of both bonding layers and electrodes are discussed. Moreover, the present solution can be used for function graded piezoelectric cantilever beams when the thickness of each bonding layer is taken as zero.

Two different kinds of heterogeneous elastic hollow cylinders are studied herein. One is a cylinder with multi-layers and another is a cylinder with continuously graded properties. A simple and convenient method is obtained to find the exact solutions of a N-layered elastic hollow cylinder submitted to uniform pressures on the inner and outer surfaces. For the hollow cylinder with continuously graded properties, the displacement method is used. A hyper-geometric equation is derived and solved, and then the exact solutions are found. The results obtained in the present paper are compared with both the numerical solutions and other findings provided by some references and good agreements are found. At the end of the present paper, some inherent properties of these two different kinds of heterogeneous graded hollow cylinders are presented and discussed.

The objective of this paper is to study the bending behavior of 2–2 multi-layered piezoelectric curved actuators. Unlike the traditional investigations based on the elementary theory of elasticity, the governing equations of a curved actuator are solved based on the general theory of elasticity and piezoelectricity. The Airy stress function method is utilized and both the piezoelectric coefficient and the thickness for different layers are taken as variables in the analysis, which makes it easy to consider the effect of elastic layers or electrodes on the bending behavior of the actuators. By introducing several recurrence formulae, the exact solutions are obtained. Furthermore, good agreement is shown by comparing the theoretical results with numerical ones.

Based on the theory of elasticity, the electrostatic behavior of functionally graded piezoelectric cantilevers is studied where the nonlinear profile of the piezoelectric parameter g31 is taken into account. Theoretical solutions and numerical results under both plane strain and plane stress conditions are obtained. It is found that the theoretical solutions obtained in the present study under the plane stress condition agree very well with both the finite element results and Hauke's experimental findings. Although no suitable experimental results under the plane strain condition can be used for a comparison at present, the theoretical solutions obtained in the present study under this loading case also agree very well with the numerical findings. At the end of this study, a general formula is suggested that can be used to calculate the tip deflection of a functionally graded piezoelectric actuator when neither the plane stress condition nor the plane strain condition is satisfied.

The frequency dispersion characteristics of pile barriers are receiving more attention due to their effectiveness and a better understanding of their behavior at attenuating middle and lower frequency ground vibrations. Based on a comprehensive study, this paper proposes a two-dimensional periodic pile barrier system, which can produce low-frequency or middle-frequency attenuation zones (AZs). Periodic pile barriers are composed of periodically arranged hollow piles filled with either soft or hard in-fill materials. Finite element method and plane wave expansion method are first used to study dispersion curves, AZs, and corresponding wave dispersion mechanisms. Influencing factors of the periodic pile barrier on the AZs are then identified based on a parametric study. To further illustrate the effectiveness of the vibration attenuation, a three-dimensional pile–soil finite element model with combined periodic pile barriers is analyzed, and the frequency ranges of vibration reduction are found to b...

Both multi-layer piezoelectric cantilevers and multi-layer piezoelectric composite cantilevers are studied based on 2D linear theory of elasticity and piezoelectricity. Both the piezoelectric coefficient and the thickness for different layers are taken as variables. As opposed to traditional investigations based on the elementary theory of elasticity, the present investigation gives exact solutions for the variation of these parameters by introducing several recurrence formulae. The solutions obtained in the present paper are compared with numerical results and the results obtained by other investigators; good agreement is found.

The bond decay at the bar–concrete interface under variable fatigue loads is investigated in this paper. Two kinds of loading paths are considered: low- and high-amplitude cycles. Based on the shear-lag model, the governing equations of the problem are established and solved with reference to three different interfacial degradation models. By the aid of Paris formula, the interfacial debonding rate, the debonded length, and the pull-out force are studied. The effect of the amplitude of the middle applied load and of several material parameters on bond decay is discussed. It is found that the power-degradation model is suitable for short embedment lengths, while both the linear-degradation model and the modified power-degradation model are advantageous in study of bond in long embedment length. It is also found that interfacial friction plays an important role in resisting interfacial debonding, in spite of the effects of Poisson's contraction.

In this paper, both piezoelectric curved multi-layered actuators and functionally gradient curved actuators made of functionally gradient materials (FGM) are investigated. The exact solutions of mechanical and electrical fields of the above two types of curved actuators are obtained on the basis of the theory of elasticity. Comparisons indicate that deflections of gradient curved actuators are slightly smaller than those of curved multi-layered actuators; however, the internal normal stresses of former ones are significantly smaller. Moreover, as the number of layers increases and the depth of layers decreases, the limitation of the results of a multi-layered actuator asymptotically approaches the results of gradient actuators. It is also found that, in general, non-zero stresses exist in the gradient piezoelectric curved actuator when the actuator is subject to an external voltage. This phenomenon is quite different from the results obtained for the gradient piezoelectric flat actuator. Finally, comparisons with the FGM results are performed and good agreements are shown.

In the present paper, two kinds of thick-walled hollow cylinders are studied. One is the cylinder with multi-layers and another is functionally graded cylinder. Both the cylinders are made of piezoelectric materials. Based on the basic piezoelectric equations, the exact solutions for the elastic hollow cylinder with N-layers submitted to external voltage are obtained. For the graded hollow cylinder the exact solutions are obtained by using displacement method and three hypergeometric functions. Comparisons demonstrate that the limitation of the multilayer cases is consistent with that of graded cases.

In the present paper, a long thick-walled piezothermoelastic hollow cylinder under a symmetric thermal loading is studied. Based on the theory of elasticity, the mechanical and electrical as well as the thermal fields of the cylinder are obtained. Besides, the effects of both temperature change and the material difference between two layers on the mechanical responses and electric output of the cylinder are investigated in detail. For comparison, some discussions of numerical results are addressed at the end of this paper.

Bending behaviors of both a piezoelectric curved bi-morph actuator and a functional gradient piezoelectric curved actuator are studied and compared. The exact solutions of both mechanical and electrical fields of the actuators are obtained based fully on the theory of elasticity. It is found that non-zero normal stresses exist in the gradient piezoelectric curved actuator when the actuator is subjected to an external voltage, which is different from the results obtained in our previous works on the gradient piezoelectric flat actuator. It is also proved that the internal stresses are drastically reduced although the deflection of the gradient curved actuator is quite small. The present analytical solutions are compared with the FEM results and a good agreement is found.

In the present paper, the problem of a functionally graded piezoelectric cantilever beam subjected to different loadings is studied. The piezoelectric beam is characterized by continuously graded properties for one elastic parameter and the material density. A pair of stress and induction functions in the form of polynomials is proposed and determined. Based on these functions, a set of analytical solutions for the beam subjected to different loadings is obtained. As particular cases, series of solutions for some canonical problems can be directly obtained from the solutions of the present paper, such as for the problems of a piezoelectric cantilever beam with constant body force or without body forces, etc.

A four-point bending RC beam strengthened with FRP plate is investigated based on the theory of elasticity. Taking the adhesive layer into account but ignoring some secondary parameters, the analytical solutions of the normal stress and shear stress on concrete-adhesive interface are obtained and discussed. Besides, the pure bending region of the beam is analyzed and the ultimate load of the beam is predicted. The results obtained in the present paper agree very well with both the results of FEM and the experimental findings.

Interfacial fatigue of reinforced concrete under tension fatigue loading is simulated based on the shear-lag model. The effects of degradation of concrete strength, the loading frequency and the stress ratio as well as corrosive environment on the interfacial fatigue are considered and discussed. It is found that: (1) degradation of concrete strength and corrosive environment result in opposite effects on interfacial fatigue. (2) Degradation of concrete strength will result in larger effects on interfacial damage in low stress ratio than that in high stress ratio. (3) With a decrease of loading frequency, interfacial corrosion damage will remarkably increase though loading frequency has a small effect on fatigue crack growth in inert media.

The contact of a rubber cone with a rigid socket is analyzed by asymptotic method. The problem is treated as an axially symmetric case, and the contact surface is smooth. The stress and strain field near the apex of the rubber cone is shown to be singular, and the angular distributions of stress and strain are obtained. The analytical result is verified by numerical calculation of finite element method.

The interfacial behaviour of fibre-reinforced composites subjected to tension fatigue loading is studied based on the shear-lag model. The governing equations of this problem are obtained and solved. In order to describe the interfacial debonding, the Paris fatigue crack growth formula as well as a modified degradation model for the coefficient of friction is adopted. Finally some important values related to interfacial debonding are obtained. In the present investigation, Poisson's contraction is considered.

In this paper, a novel energy transducer named double piezoelectric energy harvesting cell (DPEHC) consisting of two flex-compressive piezoelectric energy harvesting cells (F-C PEHCs) is proposed. At the very beginning, two F-C PEHCs, a kind of cymbal type energy transducer, are assembled together sharing the same end just in order to be placed steady. However, throughout an open-circuit voltage test, additional energy harvesting performance of the DPEHC prototype appears. Taking the interaction between the two F-C PEHCs into account, a mechanical model for analyzing the DPEHC is established. The electric output of the DPEHC under harmonic excitation is obtained theoretically and verified experimentally, and good agreement is found. In addition, as an inverse problem, the method for identifying the key mechanical parameters of the DPEHC is recommended. Finally, the additional energy harvesting performance of the DPEHC is quantitatively discussed. Numerical results show that the additional energy harvesting performance of the DPEHC is correlated with the key mechanical parameters of the DPEHC. For the present DPEHC prototype, the energy harvesting addition is over 400% compared with two independent F-C PEHCs under the same load condition.

A new type of periodic foundation (PF) with rotational oscillators was developed, and its locally resonant attenuation feature was analyzed numerically and experimentally. The proposed PF was composed of a concrete matrix in which local resonators consisting of steel cores with rubber linkers were attached. Finite element method was employed to comprehensively investigate influences of material and geometrical parameters on the attenuation zones. Furthermore, a scaled PF was fabricated and shake tests were performed. The locally resonant mechanism within the rotational resonator can produce extremely low-frequency wave-forbidding capability. The results demonstrated that a PF can isolate seismic waves with frequencies lower than 10 Hz, sufficient to serve as a seismic isolation foundation for civil engineering structures. This kind of foundation system opens up new perspectives for the development of seismic isolation foundations for low-frequency applications.

The concept of periodic materials, based on solid state physics theory, is applied to earthquake engineering. The periodic material is a material which possesses distinct characteristics that do not allow waves with certain frequencies to be transmitted through; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. In designing a periodic foundation, the first step is to match band gaps of the periodic foundation with the natural frequencies of the superstructure. This is an iterative process. Starting with a design of the periodic foundation, the band gaps are identified by performing finite element analyses using ABAQUS. This design process is repeated until the band gaps match natural frequencies of the superstructure, and the field tests of a scaled specimen are conducted to validate the design. This is an on-going research project. Presented in this paper are the preliminary results, which show that the three dimensional periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitations.Copyright © 2014 by ASME

This paper presents accurate electromechanical analysis of piezoelectric beam-type transducers with interlayer slip, based on the Euler-Bernoulli beam theory. The closed solutions of two different kinds of piezoelectric beam-type transducers under external harmonic loads are derived. The effects of the interfacial slip parameter on the responses of the transducers are discussed. Comparisons with other related experimental and theoretical results are also given, and good agreement is found.

An analytical model of the dynamic characteristics of an axially polarized multilayer piezoelectric/elastic composite cylindrical transducer is proposed in this paper. Based on the plane stress assumption, the dynamic analytical solution of the transducer under an external harmonic voltage load is obtained, and the electric admittance is also derived analytically. Inherent properties of the transducer, such as resonance and anti-resonance frequencies, are presented and discussed. In addition, comparisons with other related investigations are also given, and good agreement is found. The present investigation is very helpful for the design of axially polarized multilayer piezoelectric/elastic composite cylindrical transducers, which can be used in applications related to ultrasonic and underwater sound waves.

Smart aggregate (SA), as a piezoceramic-based multi-functional device, is formed by sandwiching two lead zirconate titanate (PZT) patches with copper shielding between a pair of solid-machined cylindrical marble blocks with epoxy. Previous researches have successfully demonstrated the capability and reliability of versatile SAs to monitor the structural health of concrete structures. However, the previous works concentrated mainly on the applications of SAs in structural health monitoring; no reasonable theoretical model of SAs was proposed. In this paper, electromechanical properties of SAs were investigated using a proposed theoretical model. Based on one dimensional linear theory of piezo-elasticity, the dynamic solutions of a SA subjected to an external harmonic voltage were solved. Further, the electric impedance of the SA was computed, and the resonance and anti-resonance frequencies were calculated based on derived equations. Numerical analysis was conducted to discuss the effects of the thickness of epoxy layer and the dimension of PZT patch on the fundamental resonance and anti-resonance frequencies as well as the corresponding electromechanical coupling factor. The dynamic solutions based on the proposed theoretical model were further experimentally verified with two SA samples. The fundamental resonance and anti-resonance frequencies of SAs show good agreements in both theoretical and experimental results. The presented analysis and results contribute to the overall understanding of SA properties and help to optimize the working frequencies of SAs in structural health monitoring of civil structures.

In this paper, a flex-compressive piezoelectric energy harvesting cell (F-C PEHC) is proposed. This cell has a large load capacity and adjustable force transmission coefficient assembled from replaceable individual components. A statically indeterminate mechanical model for the cell is established and the theoretical force transmission coefficient is derived based on structural mechanics. An inverse correlation between the force transmission coefficient and the relative stiffness of Element 1's limbs is found. An experimental study is also conducted to verify the theoretical results. Both weakened and enhanced modes are achieved for this experiment. The maximum power output approaches 4.5 mW at 120 kΩ resistive load under a 4 Hz harmonic excitation with 600 N amplitude for the weakened mode, whereas the maximum power output approaches 17.8 mW at 120 kΩ under corresponding load for the enhanced mode. The experimental measurements of output voltages are compared with the theoretical ones in both weakened and enhanced modes. The experimental measurements of open-circuit voltages are slightly smaller for harmonic excitations with amplitudes that vary from 400 N to 800 N and the errors are within 14%. During the experiment, the maximum load approaches 2.8 kN which is quite large but not the ultimate bearing capacity of the present device. The mechanical model and theoretical transmission coefficient can be used in other flex-compressive mode energy transducers.

In this paper the elastostatic field near the tip of an interface crack between two materials is analyzed with the fully nonlinear theory. By dividing the crack tip field into narrowing sectors and an expanding sector, the asymptotic equations for the crack tip field are derived and solved. The singular characters of stress and strain near the crack tip are revealed. The crack opening shape is discussed for various cases. It is shown that when large deformation is taken into account the oscillatory singularity does not occur.

Cement based piezoelectric composites can have not only low frequency, but also good compatibility with the concrete, which is perfect for measuring the properties of the civil engineering structures. However, up till now there have been only a few literatures dealing with the theoretical analysis of cement based piezoelectric composite, especially for the 2–2, 0–3 and 1–3 cement based types. Based on the general theory of elasticity and the dynamic theory of piezoelectricity, the dynamic behavior of 2–2 cement-based piezoelectric actuator is investigated under the harmonic electric signal. The actuator consists of 2 cement layers and 1 piezoelectric layer. Considering the poling layers between the cement layer and the piezoelectric layer as the elastic layer, the exact solutions of the mechanical and electrical fields of the actuator are obtained by utilizing Airy stress function method. Furthermore, the curves of displacement or stress along axial direction and other conclusions are given and discussed. Finally, it can be seen that the analytical model established in this paper works very well, which could benefit the design of this kind of cement-based smart devices.

Based on the theory of elasticity and piezoelectricity, a dynamic model of laminated elastic-piezoelectric rectangular plates is considered. The bending equations are established and solved, taking the nonlinear behavior of the piezoelectric material into account. The resonance frequency of a laminated piezoelectric rectangular plate with four kinds of different boundary conditions is then investigated. The present results agree very well with the experimental findings and can be extended to practical applications, such as considering the effect of an epoxy package on the resonance of piezoceramic plate.

The band structures of bending waves propagating in the phononic crystal thin plates with point defect are explored based on the supercell technique combined with the improved plane wave expansion method. The plate is composed of a periodic array of circular crystalline Al2O3 cylinders embedded in the epoxy matrix for square lattice. The point defect is introduced by changing one of the cylinders' radii. The results show that the defect modes exist in the first band gap, the frequencies and the numbers of the defect modes are strongly dependent on the defect filling fraction and the filling fraction. All the flat defect bands appearing in the first band gap are nondegenerate. For a given defect filling fraction, there are up to five nondegenerate defect bands emerging inside the first band gap, and the frequencies of defect bands increase with the filling fraction increases. The defect bands disappear at very low or very high filling fractions. For a given filling fraction, three nondegenerate defect bands appearing near the upper edge of the gap move to the middle as the defect filling fraction is reduced, and the edges of the first band gap remain hardly changed. The study of the displacement distributions associated with the three defect modes shows that the flat bands correspond to the special localized frequencies of the waves. For the two lower defect modes, the displacement amplitudes around the defect are much bigger than that at or far away from the defect. However, for the higher defect mode, the displacement amplitude reaches the maximum at the location of the defect and decays rapidly with the distance away from that. Obviously, the bending waves correspond to such three modes are so localized at or near the defect that they can not escape into the surrounding phononic crystals. That is, the point defect behaves like a resonant vacant.

Till now only a few of literatures related to the theoretical analysis of cement based piezoelectric composite, especially for the 2-2, 0-3 and 1-3 cement based piezoelectric composites. Based on some experimental investigations, the analytical models for the dynamic properties of 2-2 cement based piezoelectric sensors have been established in this paper. Moreover, the exact solutions have been obtained by using the displacement method and comparisons as well as discussions with the experimental results have also been presented and good agreements have been found. It is found that the analytical model established in this paper works very well, which is benefit to the design for this kind of smart devices.

Theoretical models of piezoelectric energy harvesting from railway systems using patch-type and stack-type piezoelectric transducers are studied. An infinite Euler–Bernoulli beam on a Winkler foundation subjected to moving multi-loads is adopted to describe the dynamic behavior of railway track. The voltage and electric power of piezoelectric transducers installed at the bottom of a steel rail are derived analytically. Comparisons with earlier works and experimental results are given, indicating that the present solutions are reliable. Additionally, a parametric study is conducted to discuss the effects of axle loads, running velocity and load resistors on the solutions. The numerical results show that patch-type and stack-type piezoelectric transducers can harvest the available energy from track vibration to supply power for a wireless sensor network node and can also serve as sensors to monitor basic train information, such as the running velocity, the location and the axle load. The present investigations provide a theoretical guide in the design of piezoelectric patch and stack energy harvesters used in railway systems, which can serve as power sources for distributed wireless sensor networks in remote areas. The research results also demonstrate the potential of piezoelectric patches and stack harvesters in designing self-powered wireless sensor networks used in railway systems to ensure train operation safety.

Based on the concept of phononic crystals, periodic foundations made of periodic materials are investigated in this paper. The periodic foundations can provide low frequency band gaps, which cover the main frequency ranges of seismic waves. Therefore, the periodic foundations are able to protect the upper structures during earthquake events. In this paper, the basic theory of three dimensional periodic foundations is studied and the finite element method was used to conduct the sensitivity study. A simplified three-dimensional periodic foundation with a superstructure was tested in the field and the feasibility of three dimensional periodic foundations was proved. The test results showed that the response of the upper structure with the three dimensional periodic foundation was reduced under excitation waves with the main frequency falling in the attenuation zones. The finite element analysis results are consistent with the experimental data, indicating that three dimensional periodic foundations are a feasible way of reducing seismic vibrations.

A novel adjustable multifrequency axially polarized multilayer composite cylindrical transducer is developed in this paper. The transducer is composed of two parts: an actuator part and a sensor part. Each part is considered as a multilayer piezoelectric/elastic composite structure. The actuator part is utilized to actuate the transducer, while the senor part is used to adjust its dynamic characteristics through connecting to an external electric resistance. Based on the plane stress assumption, the radial vibration of this new kind of transducer is analyzed, and its input electric admittance is derived analytically. Comparisons with the earlier works are conducted to validate the theoretical solution. Furthermore, numerical analysis is performed to study the effects of the external electric resistance on the transducer's dynamic characteristics, such as resonance and anti-resonance frequencies, as well as the corresponding electromechanical coupling factor. Numerical results show that the multifrequency cylindrical transducer can be designed through adjusting the external electric resistance and the ratio of piezoelectric layer numbers between the actuator part and the sensor part. In addition, the optimized transducer can be proposed at the matching electric resistance. The proposed cylindrical transducer plays an important role in designing the cymbal transducer, which can be used in underwater sound projectors and ultrasonic radiators.

Phononic crystal is now used to control acoustic waves. When the crystal goes to a larger scale, it is called periodic structure. The band gaps of the periodic structure can be reduced to range from 0.5 Hz to 50 Hz. Therefore, the periodic structure has potential applications in seismic wave reflection. In civil engineering, the periodic structure can be served as the foundation of upper structure. This type of foundation consisting of periodic structure is called periodic foundation. When the frequency of seismic waves falls into the band gaps of the periodic foundation, the seismic wave can be blocked. Field experiments of a scaled two dimensional (2D) periodic foundation with an upper structure were conducted to verify the band gap effects. Test results showed the 2D periodic foundation can effectively reduce the response of the upper structure for excitations with frequencies within the frequency band gaps. When the experimental and the finite element analysis results are compared, they agree well with each other, indicating that 2D periodic foundation is a feasible way of reducing seismic vibrations. (C) 2014 AIP Publishing LLC.

The problem of energy harvesting using piezoelectric transducers for pavement system applications is formulated with a focus on moving vehicle excitations. The pavement behavior is described by an infinite Bernoulli–Euler beam subjected to a moving line load and resting on a Winkler foundation. A closed-form dynamic response of the pavement is determined by a Fourier transform and the residue theorem. The voltage and power outputs of the piezoelectric harvester embedded in the pavements are then obtained by the direct piezoelectric effect. A comprehensive parametric study is conducted to show the effect of damping, the Winkler modulus, and the velocity of moving vehicles on the voltage and power output of the piezoelectric harvester. It is found that the output increases sharply when the velocity of the vehicle is close to the so-called critical velocity.

Presented in this paper are study results of dispersion relationships of periodic structures composited of concrete and rubber, from which the frequency band gap can be found. Two models with fixed or free boundary conditions are proposed to approximate the bound frequencies of the first band gap. Studies are conducted to investigate the low-frequency and directional frequency band gaps for their application to engineering. The study finds that civil engineering structures can be designed to block harmful waves, such as earthquake disturbance.

Guided by the recent advances in solid-state research in periodic materials, a new type of layered periodic foundation consisting of concrete and rubber layers is experimentally investigated in this paper. The distinct feature of this new foundation is its frequency band gaps. When the frequency contents of a wave fall within the range of the frequency band gaps, the wave, and hence its energy, will be weakened or cannot propagate through the foundation, so the foundation itself can serve as a vibration isolator. Using the theory of elastodynamics and the Bloch–Floquet theorem, the mechanism of band gaps in periodic composites is presented, and a finite element model is built to show the isolation characteristic of a finite dimensional periodic foundation. Based on these analytical results, moreover, a scaled model frame and a periodic foundation were fabricated and shake table tests of the frame on the periodic foundation were performed. Ambient, strong and harmonic vibration attenuations are found when the exciting frequencies fall into the band gaps.

An analytical model of the dynamic properties of the 2–2 cement based piezoelectric transducer is proposed using the piezoelectric effect, based on Li's experiments. Then, the exact solutions are obtained by using the displacement method; comparison and discussion with Li's experimental results in related literature are also given and good agreement is found, which could be used for better understanding of Li's experiment. A theoretical method for applying the cement based piezoelectric composite in civil engineering is provided.