Advanced Materials Research Vols. 694-697

Abstract: Use the magnetic flux leakage (MFL) of transformer to excite sound interference for noise reduction. Piezoelectric transducer made MFL energy converted into vibration. It could excite acoustic cavity to produce interference sound. Transformer magnetic flux leakage and noise was analyzed by COMSOL Multiphysics. The sound pressure and the value of MFL calculated could be the guidance of muffler device design and installation location.

Abstract: The mathematical model of the electro-rheological fluid engine mounting system is set up, Combining the electro-rheological fluid effect with hydraulic mount technology and considering the flexibility of the car frame. The simulation model of electro-rheological fluid engine mounting system is build up by the Simulink module of Matlab software to simulate the representative situations of the system, and the displacement and acceleration characteristic curves of the powerplant and the car frame is received. The simulation results indicate that the vibration isolation capability of the system with electric field is better than the one without electric field.

Abstract: Using parallel isolation bearing to story isolation seismic system, establish a two material-points simplified model and a dynamic differential equation. Solve this dynamic equation by Newmark - β method and MATLAB language programming. A 4-story frame structure is employed as an example, to discuss the responses such as horizontal displacement, velocity and acceleration，and investigate the influence of slider bearing burden weight ratio to the structure.

Abstract: The paper studies the dynamic characteristics of liquid sloshing in TLD rectangular container, and verifies the feasibility of finite element numerical simulation, by the theory and finite element numerical simulation of liquid sloshing. Similarly employing the verified numerical simulation method, we get the sloshing frequency and mode of liquid sloshing in TLCD u-tube container.

Abstract: The vibration of pipe systems not only worsens their working environment, but also may result in the loosening of mechanical connections between pipelines, as well as the structural fatigue damages. This paper presents a new method for vibration control of pipe systems, by specially designing some pipe structures based on two vibration reduction mechanisms of phononic crystals, for the vibration frequency in the actual tests. Some numerical analyses are then performed about the effects of the parameters of vibrator, for instance, the ratio of material components, and the numbers of period. The simulation results demonstrate that the proposed phononic crystals structures can reduce the vibration of pipe systems effectively.

Abstract: Tire noise is an effective noise source of vehicles. The mechanism of tire noise is very complex. Moreover, the external factors can affect tire noise. Then, it is very difficult to estimate the tire noise with mathematic models and computational methods. Therefore, the test experiment using anechoic and semi-anechoic chamber is important to study the characteristics of the tire noise. In this paper, the factors affecting the noise of radial tire are analyzed; the noise characteristics of the radial tire are obtained by experiments. From the experiment results, it can be seen that tire wear is the main factor of tire noise.

Abstract: Though the test of a certain domestic car which cause the car body vibration and cab noise under the idle with turning on and off air conditioning system. The result of the test is analyzed by sound pressure and vibration spectrum, which analysis spectrum-frequency characteristics, affecting factors and noise sources of noise.Finding out the main noise and vibration of interior noise caused by air conditioning and refrigeration system; the car dash panel and body wall is the main transmission route of cab vibration;the people feel uncomfortable when opening the air conditioning under idle, because beat frequency is caused by the compressor and engine. It provides a certain reference for the reduction of noise and vibration of car's air conditioning and refrigeration system.

Abstract: With the purpose of realizing the analysis of mechanical structure dynamic characteristics and inhibit vibration and noise, combined with the analysis of a certain type of high speed sewing machines vibration characteristics, we carry on the concrete experimental modal analysis, and compare the results of the experimental modal analysis with the results of spectrum analysis. The analysis results show that the second order natural frequency of the shell is close to two octaves under the normal working speed of sewing machine and it will lead to resonance. Enhancing the structural rigidity and the natural frequency under this modal to avoid resonance frequency is the key to improve vibration resistance of the structure.

Abstract: Respectively applied Trimble R8 GNSS/RTK, Leica TCA2003 3D coordinates measurement and SPRINTER 200M elevation of sight to synchronously monitor the deflection displacement of an underdamped oscillation, it has a 0.5 Hz design frequency and mm level amplitude in this test. Based on the FFT algorithm, spectral information was independently calculated out from these observed data of deflection displacement. Combined the spectrogram with the deflection displacement of R8, TCA2003 and SPRINTER 200M monitoring points, this paper makes a comparative analysis. The results show that the TCA2003 automatic tracking measurement can not only accurately measure the dynamic changes in the process of the damped oscillation dynamic deflection but truly reflect the structure of the dynamic deformation characteristics; the SPRINTER 200M digital leveling can monitor the overall trend of dynamic deflection, but get a harmonic frequency; and GNSS/RTK only acquires a harmonic.

Abstract: Modal damping ratios are very difficult to predict at the design stage, but have a strong influence on the dynamic structural behavior. This paper describes the research process of damping ratio of the tower equipment. First of all, calculation methods of damping ratio of the tower equipment complying with different standards have been analyzed. Then, the damping ratio of process tower equipments has been calculated by using different calculation methods compared to its real data. The results show that it does not accurately predict the damping ratio of the large tower equipment using existing calculation methods. As a result, the theoretical or semi-empirical formula must be put forward to calculate the damping ratio of the industrial tower.