Applied Mechanics and Materials Vol. 482

Abstract: The finite element model of piezoelectric cantilever laminate is established with ANSYS and the vibration character of the model is carried out. The vibration characters of different size of piezoelectric laminate and different voltage is compared. The maximum displacement demonstrates the trend of decreasing step by step with increasing the thickness of the base steel layer. The displacements of the same base steel layer and piezoelectric layer are increasing with the incremental voltage.

Abstract: A semi-active suspension system is researched for a heavy tracked vehicle to improve its suspension performance. This is achieved through a vane magnetorheological damper (VMRD) with special magnetic circuit which may attenuate the leak of MRF from assembly gap. A innovative strategy named frequency domain control (FDC) is proposed based on a conclusion that, in the frequency domain,the influence of damping coefficient to transmissibility for different suspension performance indicators is in good consistency. FDC only requires accelerometers mounted on sprung mass, meaning low price and high reliability that the tracked vehicle requires. The experiment indicates the designed semi-active suspension system based on VMRFD has an excellent vibration suppressing ability.

Abstract: In order to study the effects of high-speed railway in tunnel on vibration response of upper building, the Vehicle-Track-Tunnel-Soil-Building coupling dynamic model was established, and the reaction force of fasteners was used to transmit between Vehicle-Track coupling dynamic model and Tunnel-Soil-Building finite element model. According to modal analysis for typical section of building, sensitive frequency range and sensitive structure locations were obtained. In terms of two conditions, Tunnel-Building Integrated Structure and building are evaded from tunnel for some distance, 1/3 octave vibration level and VLZ vibration acceleration level for all measuring points were calculated to analyze the vibration response of building. The results are shown as follows: for Tunnel-Building Integrated Structure, the overall vibration level is high,which is above 65dB. 2-3dB will be reduced by decreasing speed and improving standard of track. when building is evaded from tunnel for some distance, with larger evaded distance, the vibration response is slighter. However, when evaded distance is above 30m, vibration may be amplified ,so its necessary to select proper distance. Vibration response of structure is most strong when 4 lines meet under building, so strict limitation on meeting condition of trains can effectively reduce vibration level.

Abstract: The design method research of position schemes for particle dampers applied to a flywheel under sinusoidal excitation has been investigated, in which discrete element method (DEM) and finite element analysis are used to study the relationship between the damping capacity of dampers filled with different metal particles and the dimensionless acceleration amplitude, and the specific parameter of radial position is introduced to discuss the influence on particle damping caused by different dampers attachment locations. A series of corresponding experimental investigation are conducted subsequently and the results indicate an auxiliary position scheme if the acceleration response of optimum location exceeds the threshold. It can be concluded that with the help of the specific parameter of radial position, the experiment results can be well explained, in addition, the design efficiency and accuracy will be raised, especially in the condition that the particles mass is strictly limited.

Abstract: The mathematical model of feed system of CNC machine tool was established base of Lagrange Equation and energy principle, then uses the Runge-Kutta method to solve the equation, and analyzes the influence that the parameters to the vibration displacement of ball screw. According to the result of orthogonal test, it is concluded that the most important three factors which influence ballscrew vibration displacement were the ball screw's lead h, the table quality m and the longitudinal contact stiffness kn in the connection of workbench and ballscrew. On the feed system test-bed, the longitudinal amplitude, torsional amplitude and horizontal amplitude of ball screw were measured, the results show the larger the ball screw's lead and the quality of workbench, the greater the amplitude of ball screw, the bigger the longitudinal contact stiffness kn, and the smaller the amplitude of screw.

Abstract: Wide-Chord Hollow Fan Blade is One of the New Technologies Used in Aircraft Engines. in this Paper, the Modal Analysis Method is Used to Analyze the Influence of the Rib Number and the Rib Thickness to Wide-Chord Hollow Fan Blade Vibration Characteristics. the Result Shows that the Wide-Chord Hollow Fan Blades Greatly Improves the First-Order Vibration Frequency Compared with the Solid Blades, and the First-Order Vibration Frequency of the Wide-Chord Hollow Fan Blades is Reduced with the Increasing Rib Number which is Not Good for Vibration Elimination. the Wide-Chord Hollow Fan Blades’ Vibration Frequency Changes a Little when the Rib Number is Larger than Three. in Addition, the Rib Thickness has Smaller Effect on Wide-Chord Hollow Fan Blade.

Abstract: In view of diesel engine wear fault feature extraction, feature extraction of diesel engine wear fault based on Local Tangent Space Alignment (LTSA) was put forward. This paper analyzes LTSA algorithm which reveals the characteristics of manifold learning. Take diesel engine fault diagnosis test rig as example, vibration information was got through imitating different kinds of diesel engine wear fault. LTSA algorithm was applied for dimensionality reduction. LTSA algorithm’s classification performance was compared in accordance with recognition rate of multi-class SVM. The experimental results show that LTSA has high recognition rate and is a very effective feature extraction method for diesel engine wear fault.

Abstract: To study environmental vibration problems caused by urban traffic, field test of ground vibration induced by the traffic load were carried out on a city road and attenuation of the vibration was analyzed from the time domain. Used MATLAB software to curve fitting attenuation coefficient to calculate the variation of vibration with depth. The vibration with depth was analyzed through the attenuation coefficient. The results show that the environmental vibration caused by road traffic load was mainly in vertical direction. In addition, environmental vibration in the transverse and vertical directions were both gradually decreasing with the increase of the distance from vibration source. Vibration attenuation was rapidly reduced within 10m and there was almost no vibration in 57 m.

Abstract: The problem of frequency band of acoustic transducer is the key research field. By summarizing of Tonpilz and Janus-type transducer influence factors,such as transducer structure type, geometry parameters, the rule of redressing the mechanical quality factor Q_m is investigated, and the trend of extending the frequency band by multi-mode coupling is got. By analyzing the multi-modal forms of vibration of double and triple resonance resonant, several types of extending frequency band of transducer are categorized under this forms. The advantages and disadvantages are investigated by general theory analysis of extending longitudinal vibration transducer, and the state of the art and the applications are displayed. So that the researchers are easier to understand the transducer, and can offer ideas for new design.

Abstract: Whether in the aerospace, or seismic exploration, as well as high precision operation of all trades and professions, low-frequency interference directly influences the instrument monitoring and detection precision, resulting in insufficient accuracy of the implementing agencies. The passive vibration isolation method was used by most high accuracy equipment at present, the efficiency of isolation can only achieve 60%-70%, that will have influence to the extremely precision equipment certainly. In this paper an active vibration control system was realized by using single-chip microcomputer and the PID control algorithm. System simulation model was built and experimental tests had been conducted. The interference eliminated more than 80% for 3Hz and below,can effectively improve the precision equipment to work under the low frequency interference.The system provided an effective method to suppress the low frequency interference.