Papers by Keyword: Resonance Frequency

Abstract: Vibration systems require the damping materials operating at high service temperature. In this paper, damping performance of HT100, M2052 and S316L at 350K were evaluated by applying different frequencies, strain amplitudes and heating rates. It is found that the internal friction dependence of frequency of HT100, M2052 and S316L all show a characteristic of Check function, and the resonance frequency has a negative linear correlation with the material physical parameters. The strain amplitude as well as heating rate has no obvious effect on the resonance frequencies of the materials, but significantly enhance the internal friction of the interface damping alloys such as M2052 and HT100, but small on single-phase alloys such as S316L. The internal friction mechanism for HT100 and M2052 are of static hysteresis at 350K, and HT100 and M2052 are applicable candidates for working at temperatures around 350K from the viewpoint of vibration reduction.

Abstract: Zirconia toughened alumina (ZTA) has shown a great effect in the cutting tool application due to its high hardness and comparable fracture toughness. However, the capability of the materials to be applied in as the dielectric resonator antenna (DRA) is not being discussed in detail. In this study, an attempt is made to further explore the potential of ZTA to be applied in DRA. Various related characterization techniques were applied that is subjected to DRA properties. The addition of CeO₂ (0 wt.% to 15 wt.%) on ZTA has been pressed into pellets shape and sintered at 1600 °C for 2 hours under pressureless conditions. Based on the XRD analysis, only corundum and yttria doped zirconia phases were present. Shift in position of the zirconia peaks was observed due to an existence of Ce₂Zr₃O₁₀ phase. For the DRA measurement, ZTA with 10 wt.% CeO₂ addition have resonated at 6.76 GHz which is suitable for X-band applications. Meanwhile the radiation pattern indicated the omnidirectional characteristic, which suggested that the signal could be received by this dielectric antenna in various positions. Therefore, ZTA- 10 wt.% CeO₂ have high potential to be used as DRA that operates X-band frequency range applications.

Abstract: Measuring instruments used for non-destructive testing of structures thanks to advances in electronics and electrical engineering are still more frequently applied. Among the building materials with which the ability to perform quality control using non-destructive testing methods would be most welcome is indisputably steel reinforced fibre concrete (SFRC). The paper deals with the design of new methods and methodologies that enable determination of the concentration and orientation of steel fibres in steel fibre reinforced concrete. Especially the distribution of steel fibres in concrete is the quintessential aspect of this construction material. Initial results of experiments have demonstrated the applicability of the proposed methods and methodologies and the objective of the article is to introduce it to the scientific community.

Abstract: Sacrificial layer release is the key process step of cavity structure formation of Film Bulk Acoustic Resonator (FBAR), the degree of sacrificial layer release directly determines how good or bad the resonance characteristic of FBAR is. The Constant Diffusion Coefficient (CDC) model numerical iteration of sacrificial layers etching process was simulated with MATLAB, and the etching process was also simulated with Silvaco. According to the simulation results, put forward optimum design of release window. The resonance simulations of FBAR with/without release window have been done by FEA software. The simulation results show that the aperture cavity type FBAR, i.e. the cavity type FBAR with release holes, still has distinct resonant characteristic, but the frequency of impedance zero point and impedance pole of the novel type FBAR are all drifted to higher frequency, and the effective electromechanical coupling coefficient and the quality factor are all reduced.

Abstract: According to the change of resistivity and magnetic permeability of iron load which will influence the resonance frequency in the process of induction heating, this paper presents a frequency tracking system based on the 74HC4046. It can control the output frequency of the power supply in real time, and make the power output frequency to trace the resonance frequency of load. This paper also analyses the phase compensation of the control system, and proposes a new way of phase compensation. The corresponding simulation experiment is done finally. It provides the theory basis to analyze and design an inverter power supply.

Abstract: In engineering practice, some of the structural elements take the form of a thin planar plate. For such elements, it is sometimes important to consider dangerous condition of resonance. A structural element cannot operate in the range of resonant frequencies. It is therefore necessary to determine natural frequencies and normal modes of vibration of such structural elements. Parts of the paper are the results of the analysis of natural frequencies and normal modes of vibration using FEM program Cosmos. The subject of the analysis was a thin flat circular plate considered in three modifications, i.e. free thin circular plate without hole, a thin circular plate without hole, clamped on the outer periphery, a thin circular plate with a hole, clamped on the outer and inner circumference. At the same time, Chladni patterns were obtained. They were created using the Matlab system and extraction of the outputs of the Cosmos program.

Abstract: Increasing the driving amplitude could improve the sensitivity of silicon microgyroscope, which is the effective way to enhance the performance of gyroscope. However the large driving amplitude leads to the nonlinear effect. As a result, the resonance frequency is dependent with the driving amplitude, which influences the frequency stability of gyroscope. The equivalent model of driving beam is established, and the stiffness formulas of driving beam are derivated according to the large deflection theory. The linear stiffness of driving beam is 270.1N/m and the nonlinear stiffness is 3.237×108N/m³, which are 2.7% and 6.4% different from the simulative results. Harmonic balance method can be used to establish the relationship between driving amplitude and resonance frequency. The theoretical analysis results are carried out compared with the simulative analysis results. Also the impact of driving amplitude on resonance frequency is confirmed by experiment test. This paper is significant for improving the frequency stability, and provides a theoretical basis for optimizing the structure of gyroscope.

Abstract: The probe-fed rectangular patch antenna with the Minkowski fractal structure which for 2.45GHz was simulated by using high frequency electromagnetic simulation software HFSS V11.The Simulation results showed that it was similar to side-fed square patch antenna with the Minkowski fractal structure. The resonant frequency decreased with fractal iteration, and the size of the antenna could be miniaturized. And antenna pattern unchanged with fractal iteration mostly, which meet the application requirements basically.

Abstract: Based on the theory of the chute can achieve single excitation longitudinal and bending vibration, design chute horn with longitudinal bending vibration . Using finite element analysis method combined with experiment,research on vibration characteristics of horn with longitudinal bending vibration, obtained the resonance frequency and the amplitude of longitudinal and bending of the horn, in different angle and the number of chute .Verified it can realize longitudinal bending complex vibration by opening chute on the horn, and in the different chute, and gained variation of the resonance frequency and the amplitude of longitudinal and bending of the horn, in different angle and the number of chute ,to lay the foundation for the two-dimensional ultrasonic vibration in ultraprecision cutting.

Abstract: This paper presents a general model to predict resonance frequencies for long-neck cylindrical acoustic resonators. The predicted resonance frequencies by the proposed model are compared with those measured and calculated by Panton and Millers model. It is found that the model developed in this paper can give more accurate resonance frequencies for both the first and higher modes, while the Panton and Millers model can only accurately predict the first-order frequency, and up to 4% error is observed in the predicted higher-order resonance frequencies, mainly induced by the lumped-mass simplification.