The paper presents an improved hybrid tri-stable cantilever piezoelectric energy harvester based on rotational motion, thus providing a new perspective for achieving higher efficiency in energy capture for rotational motion. The proposed system comprises a piezoelectric cantilever beam with an innovative dynamic amplifier installed at the edge of a vehicle's wheel hub. Through theoretical analysis and numerical simulations, the influence of parameters such as the mass of the tip magnetic on the piezoelectric beam, the wheel hub radius, rotational speed, and the ratio of the dynamic amplifier's spring stiffness are investigated with respect to the system's steady-state dynamic response and time-domain performance. A comparative analysis is also conducted with traditional tri-stable piezoelectric energy harvesters. The results demonstrate that the hybrid tri-stable piezoelectric energy harvester exhibits superior performance in capturing vibrational energy during rotational motion, compared to traditional tri-stable piezoelectric energy harvesters. Proper adjustments to the mass of the tip magnetic and the internal spring stiffness of the dynamic amplifier can enhance the system's output voltage and the rotational speed range of inter-well motion. Additionally, the rotational speed range of inter-well motion increases with the expansion of the wheel hub radius. However, when the rotational speed is below 100 rpm, the influence of varying the wheel hub radius on the system's output voltage is minimal.

This paper proposes an asymmetric hybrid tri-stable piezoelectric energy harvester for rotational motion (RHTPEH). The device features an asymmetric tri-stable piezoelectric cantilever beam positioned at the edge of a rotating disk. This beam is uniquely configured with an asymmetric arrangement of magnets. Additionally, an elastic amplifier composed of a vertical and a rotating spring connects the beam’s fixed end and the disk. This setup enhances both the rotational amplitude and vertical displacement of the beam during motion. A comprehensive dynamical model of the RHTPEH was developed using Lagrange’s equations. This model facilitated an in-depth analysis of the system’s behavior under various conditions, focusing on the influence of key parameters such as the asymmetry in the potential well, the stiffness ratio of the amplifier springs, the radius of the disk, and the disk’s rotational speed on the nonlinear dynamic response of the system. The results show that the asymmetric hybrid tri-stable piezoelectric energy harvester makes it easier to harvest the vibration energy in rotational motion and has excellent power output performance compared with the symmetric tri-stable piezoelectric energy harvester. The output power magnitude of the system at higher rotational speeds increases as the radius of rotation expands, but when the rotational speed is low, the steady-state output power magnitude of the system is not sensitive to changes in the radius of rotation. Theoretical analysis and numerical simulations validate the effectiveness of the proposed asymmetric RHTPEH for energy harvesting in low-frequency rotating environments.

The configuration of beam–column joints in precast concrete (PC) building structures varies widely, and different connection methods significantly affect the progressive collapse resistance of the structure. This study investigates the progressive collapse resistance of an innovative beam–column connection node frame. Finite element models of four-story, two-span space frame structures made of reinforced concrete (RC) and PC were developed using ANSYS 14.0/LS-DYNA R5.x software, employing nonlinear dynamic and static analysis to examine structural collapse behavior under bottom middle or corner column damage. Numerical results indicate that following the failure of the middle or corner column due to explosion loading, the vertical displacement and collapse rate of the PC structure with the novel connection method are less than those of the RC structure during collapse progression. Furthermore, upon removal of the middle or corner column, the residual load-carrying capacity of the PC structure with the innovative connection increased by 7% and 3.7%, respectively, compared to the RC structure. This suggests that PC structures with this type of connection demonstrate superior performance in resisting progressive collapse, offering valuable insights for future engineering applications.

Piezoelectric energy harvesting faces a primary challenge in effectively capturing low-orbit vibration energy across a broad frequency range. In this paper, we present a tri-stable piezoelectric energy harvester that incorporates a dynamic amplifier (TPEH + DM), specifically designed for efficient collection of low-orbit vibration energy. The TPEH + DM comprises a piezoelectric cantilever beam connected to an innovative dynamic amplifier at its restrained end, which enhances both the rotational and lateral displacement of the piezoelectric cantilever beam simultaneously. The governing coupled differential equations of motion for the system is derived based on the Lagrange equation, and analytical expressions for its steady-state response are obtained using the multi-scale method. The influence of factors such as the mass and the stiffness ratio of the dynamic amplifier on the steady-state dynamic output characteristics of the system is investigated using the theoretical analysis and numerical simulation. The results indicate that TPEH + DM exhibits significantly improved energy harvesting performance compared to TPEH under low-orbit external excitations. The bandwidth of inter-well motion and the TPEH + DM power output may be further increased by suitably modifying the relative stiffness between the cantilever beam and the dynamic amplifier. In addition, we analyze the time-domain behavior of the system’s output voltage using the ode45 solver under various external excitation frequencies and intensities. The results demonstrate that with appropriate adjustments to the mass of the tip magnet and the stiffness ratio of the dynamic amplifier, the proposed TPEH + DM system can harvest energy efficiently across a broad frequency range, even under low-orbit excitations.

In this paper, a non-linear tri-stable piezoelectric cantilever energy harvester with a novel-type dynamic magnifier was proposed to achieve more effective broadband energy harvesting under low-level ambient excitations. According to the generalized Hamilton principle, a mathematical distributed parameter model of the piezoelectric energy harvester was proposed. The novel-type dynamic magnifier is a system consisting of two spring masses, one placed between the fixed end of the piezoelectric beam and the L-shaped frame, and the other, between the L-shaped frame and the base. The harmonic balance method was adopted to work out the analytical expressions of the steady-state displacement, steady-state output voltage and power amplitude of the energy harvester system. The effects of the distance between the magnets, the spring stiffness of the dynamic magnifier, and the load resistance on the performance of the system were also investigated. The results show that different from that of the conventional tri-stable piezoelectric energy harvester, the frequency response curve of the proposed novel-type energy harvester system with a two-spring-mass dynamic magnifier exhibits two peaks as a result of the interactions of the coupled elastic system, where the left peak stands for the resonant value of the tri-stable piezoelectric energy harvester, while the right one the resonant value of the dynamic magnifier. It is able to achieve higher output power over a broader frequency band under low-level environmental excitations, and the harvested power can be significantly strengthened if the mass and stiffness of the dynamic magnifier are selected properly.

A distributed parametric mathematical model of a new-type dynamic magnifier for a bistable cantilever piezoelectric energy harvester is proposed by using the generalized Hamilton principle. The new-type dynamic magnifier consists of a two-spring-mass system, one is placed between the fixed end of the piezoelectric beam and the L-shaped frame, and the other is placed between the L-shaped frame and the base structure. We used the harmonic balance method to obtain the analytical expressions for the steady-state displacement, steady-state output voltage, and power amplitude of the system. The effect of the distance between the magnets, the spring stiffness ratio and mass ratio of the two dynamic magnifiers, and the load resistance on the performance of the harvester is investigated. Analytical results show that compared with the bistable piezoelectric energy harvester with a typical spring-mass dynamic magnifier, the proposed new-type energy harvester system with a two-spring-mass dynamic magnifier can provide higher output power over a broader frequency band, and increasing the mass ratio of the magnifier tip mass to the tip magnet can significantly increase the output power of the BPEH + TDM system. Properly choosing the stiffness ratio of the two dynamic amplifiers can obviously improve the harvested power of the piezoelectric energy harvester at a low excitation level.