Advanced Materials Research Vol. 705

Abstract: Based on the honeycomb sandwich structure on the supported plates of a satellite antenna, the bending effect of the honeycomb sandwich structure is analyzed with analytical method and finite element method (FEM) to design and verify the models established in the paper. Then, the analytical method without/with considering the flexural rigidity effect of the face sheets is solved. And the equivalent model of the honeycomb sandwich structure is constructed for valuating analysis. Then the three different models are analyzed with finite element method. The results show that, the flexural rigidity of face sheets can affect the bending of the structure when the thickness cant be ignored. Compared to the reality model, the bending results of the equivalent model are more conservative. Its significant in the engineering practice for the honeycomb sandwich structures.

Abstract: The purpose of the present study was to discuss the effects of solidus velocity on porosity formation of A201 aluminum alloy plate castings. With systematic change in the riser size, together with variation of thickness and length, were cast in sand molds. The sand molds with end chill for the plate castings were made of 100% silica sand. The porosity content of A201 aluminum alloy was affected by the solidus velocity in this study. The correlation between porosity content and solidus velocity is found to be split into 2 bands, each being associated with one of the different thickness of plate castings.

Abstract: Micro-metal forming is a promising technology for the manufacturing micro parts of MEMS and MST, and the mechanical behavior of material at the micron scale need to be further explored. In this work, the mechanical properties of AISI304 stainless steel foils are investigated by the micro-tensile experiments and numerical prediction. The foils with different thicknesses (10, 50, 100 and 200μm) underwent different annealing treatments to obtain different grain sizes. The micro-tensile results show the obvious dependence of the mechanical behaviors on the grain size and thickness. Corresponding, a dislocation density based constitutive model which takes into account of the different strengthening mechanisms of grain boundary and surface passivation layer, is developed. The predicted results of the model show good agreement with the experimental data. The model interprets that the surface passivation layer and grain size play an important role in the overall mechanical behaviors of the micron metallic foils.

Abstract: The researching about mechanical arm in Chinese domestic is still in the initial stage, therefore this topic is selected. The researching is doing from two aspects, they are theoretical analyzing and empirical analyzing. Through using the theory of spline and the theory of optimization, establish the mathematical model. Then in the empirical researching, the mathematical model is used. After a series of empirical tests, the correct of theoretical analyzing and empirical analyzing is confirmed.

Abstract: High quality factor is an essential requirement in the design of microsensors used for sensing and communications applications. In previous works, some analytical models have been developed for thermoelastic damping in monolayer structure and multi-layered beam. This paper proposes a new model for thermoelastic damping in symmetric, three-layered, laminated, microplate resonators. Our approach utilizes the analytical framework developed by Bishop and Kinra and Gaussian curvature. The effect of volume fraction is numerically calculated. It is noticed that the maximum damping is determined by volume fraction, which is independent of the single layer thickness. The thinner plate is, the higher frequency is that reach the maximum damping.

Abstract: In this paper we will present the analytical modeling of two different microphone membranes (one square and one circular) fabricated using the MultiMEMS process at Sensonor in Norway. In particular we built up a mathematical model of the pressurebehavior inside the cavity, when an external pressure is applied. The time constant of the exponential solution, gave us the possibility to estimate the minimum working frequencies of these devices. We compared the results that we found with both the mechanical resonance estimates from FEM models and the initial measurements of the devices presented in [.

Abstract: Due to the weak nonstationary characteristics of high-precision fiber optic gyro output random drift. In order to reduce the random drift, this paper proposes a new nonlinear, nonstationary filter method—the Empirical mode decomposition (EMD) method. Firstly some key technologies were discussed, and then proposed a Wavelet filter method of the fiber optic gyroscope based on EMD. Using fiber optic gyro data conducted off-line simulation verification. The results indicated that Wavelet filter method based on EMD can effectively remove high frequency noise compared with the ordinary wavelet filter method, and can also effectively suppress other noise. The bias instability of Gyro output from 0.0061 ° / h reduced to 0.001 ° / h. Accuracy is improved obviously.

Abstract: In this paper, a novel MEMS based LLC converter is proposed for on chip power supplies. The design is optimized based on commercially available Metal MUMPs process for fabrication. The resonant frequency is optimized at 20MHz and MEMS based variable capacitor is fabricated on the chip to tune the peak resonance frequency of circuit which varies due to the load variations. The Design is simulated in FEM based numerical software COMSOL and Intellisuite. According to analysis the magnetizing inductance of 42nH and leakage inductance of 40nH has been achieved from 16 mm² rectangular coil transformer. The total capacitance of 1500pF has been achieved from parallel plate capacitors and variation of 3pF has been achieved from variable capacitor.

Abstract: In this paper RF MEMS switchis designed for dielectric-embedded electronically switched multiple-beam (DE-ESMB) antenna array. To achieve small stiffness without buckling, a novel bidirectional Z-shaped thermal actuator is used instead of V-shaped thermal actuator, which can generate large displacement and high contact force at low actuation voltage. With the actuation current from-0.6 A to 0.6 A, the electrothermal actuator can achieve a bidirectional motion in a dynamic range of-10.08 μm to 10.17 μm.RF performances are improved by suspending the structure 25 μm from the substrate using MetalMumps process. An ON state insertion loss of-0.14 dB at 10 GHz and an OFF state isolation of-67 dB at 10 GHz are achieved on low resistivity silicon substrate.

Abstract: A Planar square stack coupled inductor coils on silicon substrate has been fabricated using MEMS technology. The fabrication process utilized a simple, cost effective process technique as well as CMOS compatible resulting to a reproducible and good controlled process. The basic characteristics of the coupled inductors were discussed in wide range of operating frequency. The analysis results showed that the geometry of the inductor coil strongly affects the basic characteristics of the coils. The results of the study have promised a good prospect for the development of fully integrated planar magnetic field generator for sensing and actuating purposes.