We analyze the performance of a piezoelectric bimorph in the flexural mode for scavenging ambient vibration energy and evaluate the dependence of the performance upon the physical and geometrical parameters of the model bimorph. The analytical solution for the flexural motion of the piezoelectric bimorph shows that the output power density increases initially, reaches a maximum, and then decreases monotonically with increasing load impedance, which is normalized by a parameter that is a simple combination of the physical and geometrical parameters of the scavenging structure, the bimorph, and the frequency of the ambient vibration, underscoring the importance for the load circuit to have the impedance desirable by the scavenging structure. The numerical results illustrate the considerably enhanced performances achieved by adjusting the physical and geometrical parameters of the scavenging structure.

No abstract

No abstract

No abstract

Corrosion property of AZ31‐xCu (x = 0, 0.5, 1.5, 3 wt%) alloys has been investigated using scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS), X‐ray diffractometer (XRD), immersion tests, and electrochemical measurements. The results indicate that the content of AlCuMg phase, main secondary phase in the Cu‐containing alloys, is positively dependent on copper concentration. Acceleration of corrosion rate is found in Cu‐containing alloys due to micro‐galvanic corrosion. AlCuMg phase acts as micro‐galvanic cathode against anodic magnesium matrixes. In this regard, the degradation rate is decreasing in the following order: AZ31‐3Cu > AZ31‐1.5Cu > AZ31‐0.5Cu > AZ31.

No abstract

We study thickness-twist vibrations and waves in an unbounded, multi-sectioned piezoelectric plate of crystals with 6 mm symmetry or polarized ceramics. An exact solution from the three-dimensional equations of piezoelectricity is obtained. Basic vibration and wave propagation characteristics are calculated based on the solution. The results are useful in the understanding and design of plate resonators, filters and acoustic wave sensors of ZnO, AlN and polarized ceramics.

No abstract