In vibration control with piezoceramics, a high coupling of the piezoelement with the structure is desired. A high coupling improves the damping performance of passive techniques like shunt damping. The coupling can be influenced by a the material properties of the piezoceramics, but also by the placement within the structure and the size of the transducer. Detailed knowlegde about the vibration behavior of the structure is required for this. This paper presents an in-depth analysis of the optimal shape of piezoelectric elements. General results for one-dimensional, but inhomogeneos strain distribution are provided. These results are applied to the case of a longitudinal transducer and a bending bimorph. It is obtained that for maximum coupling, only a certain fracture of the volume should be made of piezoelectric material&
An optimized method of vibration Energy Harvesting is based on a step-down transformer that regulates the power flow from the piezoelectric element to the desired electronic load. Taking into account parameters of the whole system, the “optimal” voltage gain the piezoelectric transformer can be determined where the harvested power is maximized for the actual level of mechanical excitation. Consequently the piezoelectric transformers can be used to boost up the conversion of mechanical strain into electrical power with considerable potential in Energy Harvesting applications. Nowadays however, the most important factor is usage of lead free material for its construction. Additional desired parameters of such ceramics include high value of piezoelectric coefficients, low dielectric losses and reasonable power density. This work for first time proposes a lead free K0.5Na0.5NbO3 (KNN) material implementation for stack type of piezoelectric transformer that is designed for load efficiency optimization of vibration energy harvester.
The present work focuses on a first study for a piezoelectric harvesting system, finalized to the obtaining of electrical energy from the kinetic energy of rainy precipitation, a renewable energy source not really considered until now. The system, after the realization, can be collocated on the roof of an house, configuring a “Piezo Roof Harvesting System”. After presenting a state of art of the harvesting systems from environmental energy, linked to vibrations, using piezoelectric structures, and of piezoelectric harvesting systems functioning with rain, the authors propose an analysis of the fundamental features of rainy precipitations for the definition of the harvesting system. Then, four key patterns for the realization of a piezoelectric energy harvesting system are discussed and analysed, arriving to the choice of a cantilever beam scheme, in which the piezoelectric material works in 31 mode. An electro-mechanical model for the simulation of performance of the unit for the energetic conversion, composed of three blocks, is proposed. The model is used for a simulation campaign to perform the final choice of the more suitable piezoelectric unit, available on the market, which will be adopted for the realization of the “Piezo Roof Harvesting System”.
Wireless body area network (WBAN) has evolved from Wireless personal area network (WPAN), a prominent area of research with vast applications in last decade. In WBAN, various wirelessly interconnected body node (BN) are implanted in or around the human body. Also due to advancement in technology a miniature low power device/BN is developed. The main challenge in WBAN body node is to maintain finite size of battery as well as to increase its capacity. Hence this issue can be resolved by using energy harvesting. Generally researchers have used piezoelectric, electromagnetic or solar harvester only. But, in this research energy harvesting using the hybrid optimization of Piezoelectric and Peltier sensors by controlling on-off timing of body nodes is introduced. A hybrid optimized algorithm is developed using MATLAB 2015b platform and extensive simulation is performed considering four different human gestures (relaxing, walking, running and fast running) which in turn improves overall Quality of Service (QoS) including average (packet loss, end to end delay, throughput) and overall detection efficiency.