This study investigates the impact of anisotropic and isotropic piezoelectric coefficients on vibrational energy harvesting using a piezoelectric patch integrated into plate-like structures. The research on energy harvesting in such configurations has garnered substantial attention in recent decades, with previous studies typically assuming isotropic piezoelectric coefficients (e_31=e_32). The investigation focuses on two common boundary conditions: cantilevered COMPOSITE plate (CFFF) and all-four-edges clamped (CCCC), employing a combination of analytical techniques and numerical simulations. The study presents comprehensive steady-state formulations for both the electrical and structural responses under harmonic force excitation. By comparing the voltage-frequency relationship between the analytical and numerical models, the accuracy of the analytical electroelastic model is verified. The findings highlight the potential for enhanced performance and increased output voltage in CFFF structures with an approximate rate between 5% to 8 % by minimizing the impact of the e_32 coefficient, whereas a decrease in output voltage is observed in CCCC structures. The findings emphasize that minimizing the impact of specific piezoelectric coefficients can lead to significant improvements in both performance and output voltage. This contributes to advancements in energy harvesting technology, highlighting the importance of optimizing piezoelectric materials to achieve better efficiency in energy harvesting applications. Additionally, the study shows that reducing the effects of e_32 in anisotropic piezoelectric harvesters can enhance energy harvesting from the vibration of a multilayer COMPOSITE cantilevered plate. This research contributes valuable insights into optimizing piezoelectric energy harvesting efficiency in plate-like structures, paving the way for advancements in energy harvesting technology.

This paper investigates the influence of temperature on the active vibration control of laminated COMPOSITE cantilever beams using collocative experimental and simulation techniques. The system identification toolbox of the MATLAB simulation tool is utilized to obtain the transfer function of the plant model. The adequate vibration attenuation of the glass-epoxy cantilever beam operating in various thermal environments is achieved using the proportional (P) and proportional-integral-derivative (PID) controllers. The vibration attenuation characteristics of the developed control algorithms are comprehensively investigated for a wide temperature range of –20 °C to 60 °C using PZT-5H PATCHES. Particular emphasis is given to the vibration control of the fundamental natural frequency of the laminated COMPOSITE cantilever beam. The obtained results of open and closed-loop models are presented in both time and frequency domains. The results indicate that for all the temperatures considered, the PID controller is found to be more effective in vibration attenuation than the P controller. The vibration attenuation performance of the cantilever beam considerably improved at the higher magnitude of temperature values. The natural frequency of the system is reduced continuously with an increase in temperature.

Considering the old methods of maintenance and repair of oil and gas pipelines such as welding or replacing a part of the damaged pipeline which include high costs and spending a lot of time, the important usage of novel methods with lower costs such as the use of COMPOSITE PATCHES can be highlighted. In this research, the strength of steel cracked pipe with COMPOSITE PATCHES of glass fibers and epoxy/polyester resins has been studied experimentally. A crack with a length of 15 mm in the longitudinal axis of the pipe is considered. The specimen was subjected to internal pressure by a hydraulic pump to evaluate the strength of the glass/epoxy and glass/polyester COMPOSITE PATCHES considering the effects of fiber distributions, fiber angles, number of layers, and dimensions. Also, a comparison has been made between glass/polyester COMPOSITEs in two modes of complete curing and initial curing. Finally, the experimental test results were compared with the numerical simulations obtained by Abaqus software and the accuracy and precision of the study were verified. Some of the obtained results indicate that arrangement and number of layers have significant roles in the pressure-bearing capacity of COMPOSITE PATCHES. In this paper, for the first time, the effect of COMPOSITE PATCHES with different fiber orientations and the number of layers as well as curing effects are considered for the cracked pipe. The results show that the pressure-bearing capacity of COMPOSITE PATCHES rises with increasing the number of COMPOSITE layers. Also, it can be seen that after complete curing of the glass-polyester COMPOSITEs, the pressure-bearing capacity rises about 3 times in 3- and 5-layer COMPOSITEs, and in 7-layer ones, it increases about 2 times.

In this paper, the first and second order approximations of Taylor expansion are used for calculating the change of each natural frequency by modifying an arbitrary parameter of a system with a known amount and based on this approximation, the inverse eigenvalue problem is transformed to a solvable algebraic equation. The finite element formulation, based on the classical laminated plate theory (CLPT) is presented for laminated COMPOSITE plates with piezoelectric PATCHES. Using the proposed FE model, sensitivity analysis is carried out, to find the effects of the changes made in the design parameters such as the piezoelectric patch thickness and the fiber angles in each layer on the natural frequencies of the structure. The inverse eigenvalue problem is solved in order to find the thickness of piezoelectric PATCHES and stacking sequence for relocating the natural frequencies.