Papers by Author: Wei Shan Chen

Abstract: Build the mathematical model and mechanical model of ultrasonic motor which using bending vibration transducer. Based on this model, analyze the contact and friction processes between driven-foot which belonging to ultrasonic motor which using bending vibration transducer and guide rail. Analyze the influence preload force make to the process of motor’s running. Take the cases of stick, slip, flight into consideration, and explain nonlinearity of the Dynamics. Do computer simulations of starting process though this model, and summarize the motor’s working results when it works under different conditions.

Abstract: A new type linear ultrasonic motor using Second-order bending and First-order torsional modes (2B-1T) is proposed. The ultrasonic motor has two driving feet and the continuous linear motions of sliders are realized by the frictional force between stator and sliders. In this new design, bending vibration is excited by d₃₃ mode, which controls the preload pressure, and torsional vibration is excited by d₁₅ mode, which generates the driving force. The elliptical trajectories of both feet are achieved, when the phase difference of the two modes is 90° in time and space. The working principle of ultrasonic motor using 2B-1T is simulated. A parametric model of the stator is designed. The sensitive analyses of structural parameters are gained with modal analysis. The characteristics and trajectories of driver feet are studied by transient analysis. These results can provide theoretical basis for the development of this new type ultrasonic motor.

Abstract: A new thin cross type rotary ultrasonic motor has been proposed for further study of this type motors characteristics. As a stator, eight semi-circular piezoelectric ceramics were attached on the upper and bottom sides of a thin hollow cross brass plate. The stator was excited by two sinusoidal voltages with a phase difference of 90° and elliptical trajectories were generated at the contact points to drive a shaft rotor. The driving principle of the motor was illustrated by degenerating two orthogonal in plane vibration modes. Based on FEM analysis, the vibration shapes and frequencies of operation modes were simulated and the relationships between the maximum displacements of the contact points and various motor parameters were obtained. A prototype was fabricated and characteristics of the motor were measured. The relationship among rotation speed, pre-pressure and voltage are no-linear. The maximum rotation speed with no load was 22.9 rpm. The merits and shortcomings of the thin cross type rotary ultrasonic motor were discussed.

Abstract: With the upsurge of marine research coming, research of the bionic fish robot is imperative. In numerous kinds of fish, batoid as the representative of the undulating pectoral fins fish are characterized by maneuverability which adapted to the complex underwater environment. This paper establishes entity model, kinematics model and dynamic model of batoid, uses means of numerical simulation to realize batoid turning in the water , and then plans turning motion of batoid. For this simulation, trajectory which is very close to the turning of real batoid is obtained to prove our modeling and simulation correct.

Abstract: This paper presents a numerical study of three dimensional flows around a self-propelled batoid with asymmetrically undulating pectoral fins. During the dynamic simulation, the difference of phase angle of the asymmetric motion is set to 180° between left pectoral fin and right pectoral fin. To evaluate the swimming performance of batoid with asymmetric undulating fins, kinematic and dynamic parameters have been used comparing with that of batoid with symmetric undulating fins. The simulation results show that asymmetric motion can achieve better starting and accelerating performance than symmetric motion.

Abstract: A D2Q9 thermal lattice Boltzmann model is applied to investigate the flow in a differentially heated cavity. The paper is intended to analysis the physics of heat and mass transfer in a closure cavity filled with air. For three Rayleigh numbers Ra, the aspect ratio K are varied from 1 to 10. Results of validation indicate this algorithm is reliable and easy for implementation. It can be found that the circulation rate of heat driven flow get lower when the K get higher. Also, the Nusselt number Nu tends to be approximated to 1 when K is higher than a critical value, which is depended on the value of Ra.

Abstract: In a previous study, the authors have presented and developed a cylindrical traveling wave piezoelectric motor using a composite transducer. This study focuses the research on the wave deformation problems in the proposed stator. Firstly, the standing wave excited by the longitudinal vibration of the transducer is analyzed, and the vibration amplitudes of particles on the driving teeth are extracted to present the objective wave shape. Then, the wave deformation of the standing wave excited by the bending vibration of the transducer is analyzed. Finally, the longitudinal and bending PZT are excited together to gain a flexural traveling wave in the stator, and the vibration amplitude distributions in radial and circumferential directions are gained. Study result indicates that there are obvious deformations on the two standing waves, which cause the motion trajectories of the surface particles are inconsistent.

Abstract: This paper firstly presented a mathematical model of the radial stiffness of a wire race ball bearing in a certain type of three-axis aircraft simulating rotary table. The Stribeck theory was used to determine the radial load distribution of the bearing. By treating the contact between balls and wires as equivalent compression springs, the relationships of these springs in series and parallel can be obtained to solve the total radial stiffness. Experiments verified the theoretical results of the radial stiffness. This work provides an effective support for further studying the complex contact dynamics of the wire race ball bearing in the future.

Abstract: A rotary ultrasonic motor using longitudinal and bending vibration modes is proposed in this study. The proposed motor contains two exponential shape horns located on two ends, and the end tips of the horns are used as the driving feet. Two groups of PZT elements (Longitudinal PZT and Bending PZT) are clamped in the middle of the motor by a double head flange bolt to excite the longitudinal vibration mode and bending vibration mode of the motor, respectively. By the composing of the longitudinal and bending vibration modes, elliptical trajectory vibrations can be generated on the end tips of the horns, which have the same rotation directions and can driving the rotor together by frictional force. After the introducing of the working principle, modal analysis is developed to tune the resonant frequencies of the longitudinal and bending vibration modes to be close with each other. At last, transient analysis is developed to gain the vibration characteristics of the motor, and the gained elliptical trajectory motions of particles on the driving parts verify the feasibility of the proposed design.

Abstract: A double driving feet linear ultrasonic motor using longitudinal vibration transducer is proposed in this paper. The stator of proposed motor contains a horizontal transducer and two vertical transducers. The horizontal transducer includes two exponential shape horns located at the leading ends, and each vertical transducer contains one exponential shape horn. The horns intersected at the tip ends where located the driving feet. The horizontal and vertical vibrations of driving feet are generated by the longitudinal vibrations of horizontal and vertical transducers, respectively. Longitudinal vibrations are superimposed in the stator and generated elliptical motions at the driving feet. The two vibration modals of stator are gained with FEM, and the resonant frequencies of two vibration modals are degenerated by adjusting the structural parameters. Transient analysis of piezoelectric coupling states the good and strong elliptical motions of driving feet, and verifies the theoretical feasibility of proposed motor.