Narrow Results

TbDyFe alloys play an important role in advanced actuator and sensor systems requiring either large displacement or large force, which may cause nonlinear response and performance degradation. In this investigation, experiments were performed to study the relevant magneto-mechanical response. The properties of magnetostriction along the direction perpendicular to the applied magnetic field were measured. The nonlinear behavior of the magnetostriction can be clearly explained in terms of domain rotating mechanism.

Due to the low vibration frequency and weak vibration energy in natural environment, the vibration energy harvester is faced with the problem of low power and low adaptability and becoming particularly difficult in actual conditions. It is necessary to improve the harvesting capacity and efficiency by optimizing the parameters of the harvester, making full use of the energy of low and unstable atmospheric vibrations. In this paper, a mathematical model is established for the cantilever magnetostrictive vibration harvester under the base excitation, including the mechanical deformation of the composite beam, and the electromagnetic results produced thereof. The mechanical-magneticelectric energy conversion relationship is duly taken into account. The additional weight, coil parameters, external resistance and other parameters of the harvester are optimized and analyzed through numerical simulation. In addition, the theoretical results are analyzed and discussed via comparison with experiments. Finally, the effects of the above factors are assessed, which allows us to obtain the optimal winding length, number of turns of the coil, and optimal tip additional mass. The experiment result shows that the optimized magnetostrictive harvester can output 12.07mW power to the external resistor under the condition of 1g acceleration mechanical vibration, with normalized power density reaching 40.2mW/cm³/g. Moreover, the optimized magnetostrictive harvester can successfully supply power for the LED display screen of the temperature sensor and a low-power thermometer.

This article studies parametric vibration and dynamic instability of a rectangular and symmetric magnetostrictive sandwich composite plate (MSCP) on a visco-Pasternak medium. The MSCP consists of three layers; a magnetostrictive layer considers the core and composites as its upper and lower faces. The MSCP subjected to temperature change, parametrically exciting force, and magnetic load is studied with consideration to geometrical von Karman nonlinearity. Based on the energy method and first shear deformation theory (FSDT), Hamilton’s principle is used to achieve the system’s governing equations and boundary conditions. In the next step, the partial differential equation is transformed into ordinary differential equations by applying the Galerkin technique. Then the equation of motion is solved using the multiple-scale method. Numerical results illustrate the stability of the sandwich plate is significantly related to the magnetostrictive parameters. In addition, the effects of significant parameters, such as the effect of amplitude response and parametric excitation or detuning parameter, coupled with the effect of foundation, thickness ratio, aspect ratio, and temperature increment on vibration characteristics, bifurcation points behavior and stability of the systems are charted, plotted and discussed. The innovation of this article is the use of magnetostrictive material in sandwich plates and the development of its mathematical relationships. It is anticipated that the results of this research can contribute to the development of future smart structural applications subjected to in-plane axial forces.

This study is based on energy harvesting from vibration and deals with the comparison of different techniques. In the present scenario, energy harvesting has drawn the attention of researchers due to a rapid increase in the use of wireless and small-scale devices. So, there is a huge thirst among scientists to develop permanent portable power sources. In the surroundings, a lot of unutilized energy is wasted which can be collected and used for power generation. Research works have been extensively carried out to develop energy harvesting devices catering to the increasing needs of being efficient and economical. Effective energy harvesting mainly depends on the design of the transducer. Different types of design techniques, material properties, and availability of energy harvesters are reviewed in this paper. The paper aims to explore the advantages and limitations of different energy harvesting principles, advances, and findings of the recent past. This study also discusses some of the key ideas for the enhancement of power output. This paper provides a broad view of the energy harvesting system to the learners, which will facilitate them to design more efficient energy harvesting devices by using different principles.

Nowadays tools based on Scanning Probe Methods (SPM) have become indispensable in a wide range of applications such as cell imaging and spectroscopy, profilometry, or surface patterning on a nanometric scale. Common to all SPM techniques is a typically slow working speed which is one of their main drawbacks. The SPM speed barrier can be improved by operating a number of probes in parallel mode. A key element when developing probe array devices is a convenient read-out system for measurements of the probe deflection. Such a read-out should be sufficiently sensitive, resistant to the working environment, and compatible with the operation of large number of probes working in parallel. In terms of fabrication, the geometrical uniformity i.e. the realisation of large numbers of identical probes, is a major concern but also the material choice compatible with high sensitivity, the detection scheme and the working environment is a challenging issue. Examples of promising applications using parallel SPM are dip-pen-nanolithography, data storage, and parallel imaging.