A piezoelectric vibration energy harvester (PVEH) is capable of converting waste or undesirable ambient vibration energy into useful electric energy. However, conventional PVEHs typically work in a narrow frequency range, leading to low efficiency in practical application. This work proposes a PVEH based on the principle of the nonlinear energy sink (NES) to achieve broadband energy harvesting. An alternating current circuit with a resistive load is first considered in the analysis of the dynamic properties and electric performance of the NES-based PEVH. Then, a standard rectifying direct current (DC) interface circuit is developed to evaluate the DC power from the PVEH. To gain insight into the NES mechanism involved, approximate analysis of the proposed PVEH systems under harmonic excitation is sought using the mixed multi-scale and harmonic balance method and the Newton–Raphson harmonic balance method. In addition, an equivalent circuit model (ECM) of the electromechanical system is derived and circuit simulations are conducted to explore and validate the energy harvesting and vibration absorption performance of the proposed NES-based PVEH. The response is also compared with that obtained by direct numerical integration of the equations of motion. Finally, the optimal resistance to obtain the maximum DC power is determined based on the Newton–Raphson harmonic balance method and validated by the ECM. In general, the NES-based PVEH can absorb the vibration from the primary structure and collect electric energy within a broad frequency range effectively.

This article presents a novel piezoelectric energy-harvesting device. Different from the existing designs in the literature, the proposed device is based on the principle of nonlinear energy sink in order to achieve simultaneous broadband energy harvesting from the nonlinear energy sink and vibration suppression for the primary structure. First, the concept of the proposed design is described. Subsequently, system modeling and parameter identification are addressed. The performance of the apparatus under transient responses is examined through both numerical simulation and experimental study. The results show that the proposed apparatus behaves similarly as the nonlinear energy sink with the following features: 1:1 resonance, targeted energy transfer, initial energy dependence, and so on. Broadband voltage output is achieved when the nonlinear energy sink is activated.

This study focuses on the optimum design of the damped dynamic vibration absorber (DVA) for damped primary systems. Different from the conventional way, the DVA damper is connected between the absorber mass and the ground. Two numerical approaches are employed. The first approach solves a set of nonlinear equations established by the Chebyshev’s equioscillation theorem. The second approach minimizes a compound objective subject to a set of the constraints. First the two methods are applied to classical systems and the results are compared with those from the analytical solutions. Then the modified Chebyshev’s equioscillation theorem method is applied to find the optimum damped DVAs for the damped primary system. Various results are obtained and analyzed.

The phenomena of sub- and super-harmonic responses make up one of the prominent nonlinear characteristics of a beam with a breathing crack. In order to fully understand the behaviors of sub- and super-harmonic resonances, it is necessary to analyze the nonlinear vibration of a beam-like structure with a breathing crack. In this study, a new stiffness model that considers the influence of the partial crack closure is proposed to model the stiffness variation of the cracked beam. Based on the finite element model of a beam with a breathing crack, the multiple-scale method is proposed to analyze the nonlinear vibration of a cracked beam subjected to harmonic excitation, and the relation between the nonlinear vibration of the cracked beam and the system parameters is obtained. An experiment is conducted to validate the analytical results. The study shows that the nonlinear responses of a beam with a breathing crack are affected by both the structural parameters and the crack parameters.

This article investigates the effectiveness of using a non-traditional vibration absorber for the purpose of simultaneous vibration suppression and energy harvesting. Unlike the commonly used vibration absorber in which the absorber damper is attached to the primary mass, the non-traditional vibration absorber under study has its damper connected between the absorber mass and the ground. In this article, an apparatus of such a configuration is developed. It consists of a primary system subjected to a ground excitation and the non-traditional vibration absorber whose frequency and damping can be tuned. An electro-magnetic device serves as both the absorber damper and the energy harvester. The optimum parameters of the vibration absorber are derived based on the classical “fixed-points” theory. The mechanism of the electro-magnetic damper is developed and its energy harvesting performance is investigated. The results are validated using both computer simulation and experiment. The study shows that when the vibration absorber is optimally tuned with respect to the frequency tuning ratio and load resistance, the frequency response function of the primary mass can be made near flat in a wider frequency band. It also demonstrates that the dual purpose of vibration suppression and energy harvesting can be achieved with the proposed absorber.

In the last few decades, structural health monitoring (SHM) has been an indispensable subject in the field of vibration engineering. With the aid of modern sensing technology, SHM has garnered significant attention towards diagnosis and risk management of large-scale civil structures and mechanical systems. In SHM, system identification is one of major building blocks through which unknown system parameters are extracted from vibration data of the structures. Such system information is then utilized to detect the damage instant, and its severity to rehabilitate and prolong the existing health of the structures. In recent years, blind source separation (BSS) algorithm has become one of the newly emerging advanced signal processing techniques for output-only system identification of civil structures. In this paper, a novel damage detection technique is proposed by integrating BSS with the time-varying auto-regressive modeling to identify the instant and severity of damage. The proposed method is validated using a suite of numerical studies and experimental models followed by a full-scale structure.