Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
Comb-drive devises have been widely applied in many fields. However, the\napplication of high frequency sensor, such as rocket chamber, still remains\nproblems. In this work, a finite element code was used for the design, optimization\nand visualization of a comb drive accelerator. In the simulation results,\nthe post-optimization design has high performance in high frequency oscillation\noperating environment. The optimization is based on the ideal eigenfrequency\nand Nelder-Mead method. The 3-D working conditions are realized\nby testing and comparing the time and frequency domain of pre-optimized\nand optimized design whose frequency ranges from 2000 Hz to 5000 Hz. Finally,\nthe electric potential and capacitance in comb drive are visualized,\nwhich shows the better electric signals and displacements....
In this study, we discuss the dynamics of a type of hanging truss structural system consisting of rigid and wire members,\npart of which are SMA (shape memory alloy) wires. This kind of truss structure has the capability of vibration isolation\nand absorption. Characteristics of zero compressive stiffness of wire members, SMA wire members and hanging configuration\nof the structure itself contribute to the effect of vibration isolation. The hysteretic loop of SMA wires plays\na significant role in vibration attenuation. Mathematical models for this kind of dynamic problem are developed. Calculation\nprocess is introduced to take into account the mechanical characteristics of SMA and wire members. Dynamic\ncharacteristics are discussed; simultaneously, the effects of vibration isolation and attenuation have been confirmed. On\nthe basis of the numerical calculations, advantages of combinations of various types of wire members, including the truss\nunits having no bracing wires have been demonstrated....
In this study, we research about comb-drive micro-structure, which is a\nMEMS device used to measure velocities and accelerations. To ensure the accuracy\nand visualization of the result, we simulate the dynamics of the comb\ndrive using COMSOL Multiphysics, meanwhile introducing the concept of\nre-meshing. We aim to find the optimal comb-drive-building material, which\ncan provide the device with the most desirable first eigenfrequency. According\nto the optimization process, silver is the most suitable construction material.\nAfterwards, the electric responses of both the optimized device and the\npre-optimized one are analyzed in frequency domain and stationary study.\nWe conclude that the capacitance change is positively related to frequency in a\nlinear manner, and that the optimized device has a larger increment of both\ndisplacement and capacitance per unit of frequency change than the pre-optimized\none, showing that the optimization of material realizes our goal of enhancing\nelectrical performance....
The sandwich structure is of great interest because of its advantage of combining\nlight weight and high flexural stiffness. Many previous researchers have\nstudied the failure modes in sandwich structures and the effects on the load\ncapacity caused by the change of the constituent materials� properties. In this\nresearch, by applying Finite Element Analysis (FEA) method, we simulated a\ncantilever beam composed of a sandwich structure in Abaqus, to find out the\npreferred design principles that help decrease the stress and displacement in\nthe beam when applied a uniform load. We also determined the effect of the\ncore geometry on decreasing the displacement and the stress in the beam....
This paper presents a method for evaluating the availability of lead-acid battery test equipment and designs the\ncorresponding evaluation mathematical model. International standard IEC60896-2 specifies the lead-acid battery\ninternal resistance level. Because the internal resistance value is usually micro-Ohm level and the lead-acid battery\nhas special electrochemical characteristics, it�s very difficult to measure it. Until now no authority can officially\nprovides the actual resistance value for a given battery. However, the industry has agreed that the internal resistance\nwill gradually increases during the use of the battery and the performance of the battery has close relationship with\nthe change of the internal resistance, so even if the measurement equipment can not measure the absolute actual\nresistance, but as long as the battery can be measured a small change in internal resistance, it has a high availability.\nIn this paper, we propose a micro-incremental verification method and a mathematical model to facilitate, accurately\nand quickly verify whether the battery internal resistance test equipment can accurately and stably measure the internal\nresistance of the battery, and provide technical verification reference for selecting the battery measuring equipment....
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