With the growth of technology and population, the human need for energy is constantly increasing. Renewable energy sources are the best option to supply this. In this regard, the use of piezoelectric materials to convert environmental vibrations into electrical energy as an energy source for electrically powered electronic components is one of the available options. In the present paper, the shape of a unimorph piezoelectric actuator has been optimized. It is assumed that this beam is triggered by a harmonic base. In this paper, the energy harvesting system, along with its electrical circuit, is simulated in Comsol software. In this software, frequency responses of the voltage, current, and electrical power of the system are obtained and power sensitivity analysis has been performed in regard to the shape parameters of the beam. The goal of this paper is to obtain a more optimal state for the beam shape in order to gain more power. This is usually done through optimization methods. In this research, the adopted optimization techniques are all zero-order, which use only the value of the objective function.

Periodic piezoelectric beams have been used for broadband vibration energy harvesting in recent years. In this paper, a periodic folded piezoelectric beam (PFPB) is introduced. The PFPB has special features that distinguish it from other periodic piezoelectric beams. The Adomian decomposition method (ADM) is used to calculate the first two band gaps and twelve natural frequencies of the PFPB. Results show that this periodic beam has wide band gaps at low frequency ranges and the band gaps are close to each other. Results also show that the PFPB can efficiently generate voltage from the localized vibration energy over the band gaps. The natural frequencies of the PFPB are close to each other and most of them are out of the band gaps. Therefore, the PFPB can also generate the maximum voltage over a relatively wide frequency range out of the band gaps. In order to show these features better, the voltage output of the PFPB over a wide frequency range is calculated using the ANSYS software and compared with that of a conventional piezoelectric energy harvester. The ANSYS is also used to validate the analytical results and good agreement is found.

The active vibration control of a smart cantilever rotary beam, using dual sensor and actuator piezoelectric patches stuck on the outer surface of the beam, is studied. Motion equations are discretized by finite element method with 6 and 9 DOF elements for parts without piezoelectric patches and with them, respectively. Several types of controllers such as LQR, LQG and rate feedback controller are employed to actively control vibrations of the beam. Simulation results exhibit a better performance in terms of settling time for the LQR controller due to all states’ feedback; while rate controller is only relying on the sensor patches for feedback which is convenient in terms of cost. Also, the effect of the number of piezoelectric patches is studied.

In this paper, the energy harvesting by porous beams exposed to the external fluid flow is studied. The electromechanical nonlinear differential equations of the transverse vibration behavior of porous beams exposed to external fluid flow are derived using the Euler-Bernoulli beam theory. A porous beam with concentrated mass which is equipped with a piezoelectric layer at its upper surface is considered energy harvesting. After numerically solving the governing nonlinear equations, the effect of different parameters on the generated energy is investigated. The results show that in the lock-in area, the maximum amount of energy is taken. Also, the porosity distribution has a significant effect on the maximum amplitude of the oscillations as well as the energy harvesting by the porous beam. In addition, for electrical resistance of 1000 kΩ, the maximum voltage generated for the beam with symmetrical porosity distribution in the form of wall stiffness, asymmetric porosity distribution, and uniform porosity distribution is equal to 0.39 V, 0.44 V, and 57 V, respectively, which indicates the highest energy harvesting capability of the beam with the porosity distribution of the third type.

Beams are the basic geometries in engineering and many engineering issues are simplified as a beam problem. In this paper, the dynamics and vibration analysis of composite Timoshenko beam made of epoxy graphite layers with two piezoelectric layers on both sides have been investigated. Extraction of motion equations has been conducted based on the first-order shear deformation beam theory using the Hamilton principle. The partial differential equations were converted to the first-order coupled differential equations and then they were solved by fourth-order Runge– Kutta method. The effect of piezoelectric parameters on the vibrational and dynamic response of the beam has been investigated. The results show that the natural frequency of the beam decreases with increasing the length of the neam. Among piezoelectric parameters, the parameter of C11 has a lower effect than the effective transverse coefficient of e31 in the frequency response. As the ratio of the length of the beam is lower than the thickness, the effect of C11 will be greater on the natural frequency. The effect of the other piezoelectric parameters in the frequency response has also been evaluated very small relative to these two parameters.

In this paper, a piezoelectric beam is designed to receive sound energy in a real environment. The electrical energy received from this beam can be stored in a battery or used directly by electrical circuits. The use of two simulations of copper and piezoelectric beams, including polyvinylidine fluoride, in which the length of the piezoelectric layer is shorter and located at the optimal point of the copper beam, are used in this simulation. The 100 dB speaker sound power is applied in a 1 cubic meter room considering the presence of air in the environment to the pole in the middle of the room. By making the beam 7. 8 cm long, the first bending frequency of the beam reaches close to 100 Hz. By stimulating the beam at this bending frequency, the noise effect reaches its maximum value and eventually leads to the production of a voltage of about 70 mV.

In the present paper, electrical energy harvesting from random vibrations of an Euler-Bernoulli nano-beam with two piezoelectric layers is investigated. The beam is composed of an aluminum layer together with two piezoelectric ceramic layers (PZT 5A) serving as energy harvesting sensors. In the proposed method, the equations governing the bimorph nano-beam will be analytically derived using classical beam theory with corresponding modification coefficients to the nano-structure applied. Then, the derived system of equations will be solved following Kantorovich method. Assumed boundary conditions for the nano-beam are as follows: a clamped end with the mass concentrated at the free end of the beam. Further, the input activation function of the system for energy harvesting was taken as being random. Since the objective of this research is to investigate the amount of harvested energy, the section on the results provides associated voltage and maximum output power curves with the bimorph nano-beam under random activation and input white noise, while also presenting the effects of characteristics and scale factor of the nano-particles on the amount of harvested energy.