Applied Mechanics and Materials Vols. 105-107

Abstract: In design of solar powered aircraft wing panel, vibration properties of wing panel should be considered, especially for the peak value of dynamic response. In this research, a viscoelastic damping layer is built for vibration isolation, wing panel finite element models of stiffened and no-stiffened structures base on fiber-reinforced laminates with damping layer in the middle are built. Natural frequency and displacement response are analyzed with different thickness of damping layer and structures. Result shows natural frequencies decrease as thickness increased, and that of laminates are lower than stiffened structure. The maximum displacement response value decreased when thickness increased and that of laminates is higher than structured with stiffer. The presented work is helpful for type selection and designing of solar powered aircraft wing panel.

Abstract: Rigid contact model of rotor/stator in ring type traveling wave ultrasonic motor without frictional material based on finite element method is proposed in this paper. First, the vibration of the stator is analyzed. Next, the rigid contact model is simulated by finite element method. Subsequently, the contact mechanism of the rotor/stator as well as performance of the ultrasonic motor is studied, and the performance of motors with two different kinds of rotor is compared. It is indicated that contact length of the rotor/stator along circumferential direction decreases from the outer to the inner edge and the stall torque increases and no-load speed decreases with preload force increasing. The result is identified as being useful in designing and analyzing the ultrasonic motor.

Abstract: A comprehensive nonlinear vehicle model of a tracked vehicle suspension is established by using multi-body dynamics software Recurdyn, which is used to be simulated ride comfort dynamic response. In the paper, the multi-body model dynamics vibration characters of vehicle suspension is simulated, which is accomplished by testing the model on the different roads (such as level-D,E&F Road) by different vehicle riding speed. The influence factors about ride comfort are found by the stimulation, which are the road level,the velocity of the vehicle and other parameters of the suspension system. The experiment about the vehicle ride comfort performance proves that using the multi-body model simulation in the paper could be helpful to select appropriate suspension system parameters in the structure and performance design about tracked vehicle suspension, which could give theory bases about suspension active controlling strategy of the suspension.

Abstract: In order to find out the dynamic peculiarity of piezoelectric-stack displacement-amplifying actuator, three methods: harmonic response analysis, impedance test and dynamic grating projection are used to analyze it. Experimental results indicate that the displacement-amplifying mechanism can provide large output torque; its response time is less than 0.3ms; its mutation time of displacement is less than 0.5ms, the fluctuation of displacement is less than 5um, and the change of displacement vs. voltage is linearity variety; its dynamic displacement is smooth, when discharging. After analyzing the actuator, some virtues of dynamic response peculiarity are shown: rapidly responding, tiny displacement fluctuates, fine displacement linearity, higher precision, large output torque, etc. Therefore it can be abroad applied in many micro-displacement control and drive systems, which need high precision and large displacement. Its application prospect is worth to expect.

Abstract: In the engineering background of the prototype test of a deep radial gate on three gorges dam, two methods are provided for the modal parameter identification of the radial gate, one is applying operation modal analysis (OMA) to a gate which is under flood discharge, the other one is applying experiment modal analysis (EMA) to a inactive gate with some other gates under flood discharge. This paper is based on the feasibility study on the former method. We use the natural excitation technology (NExT) combined with the eigensystem realization algorithm (ERA) to determine the dynamic characteristics of a gate. Displacement data at 7 locations were processed using NExT-ERA to extract the natural frequency and associated damping ratio. The results show the effectiveness of this modal identification methodology and the possibility of implementing it on other hydraulic structure.

Abstract: Unsteady CFD method based on realizable k-ε model is used for predicting unsteady forces of propeller working in non-uniform wake. First, CFD computations with different mesh scales were conducted at the propeller design condition, the results show that mesh refinement changed the results little. Then unsteady CFD simulation with different time step intervals was conducted for determining suitable time step interval, the results show that it is suitable for propeller rotating 3° per step. Based on the chosen mesh and time step interval, unsteady CFD simulation of propeller P4118 was conducted in 3-cycle and 4-cycle inflow, the unsteady thrust, torque and horizontal force agree well with experimental data, the results show that CFD method has good accuracy in predicting unsteady propeller forces.

Abstract: A new steel-asphalt composite seismic isolation layer is introduced briefly. Based on data of shake table tests, regression analysis by least squares method is adopted to analyze the natural frequency and the damping ratio of a new isolation layer. The calculation results show that the damping increases as the input acceleration increases because when PGA is relatively large, the lateral displacement of the isolation layer is large, the distance between the upper beam and the lower beam become smaller. The upper beam squeezes the asphalt ointment between it and brick piers. Part of the vertical load begins to transfer to the brick piers and friction occurs between brick piers and upper beam.. It is good for displacement limit of the structure.

Abstract: On the base of traditional robust optimal design in statics, in this paper, by considering the system under the incentive force of the arbitrary time function, the dynamic response robust optimal design problem, when system dynamic response can only be calculated using numerical integration. Considering the environmental interference factors in a system, derived the expression of response with a small parameter perturbation finite element method. Through the tiny fluctuation frame system in a post and beam’s elastic modulus, realize the robust optimal design of the structural dynamic response, and using New-mark method for dynamic analysis, robust optimal design is applied in dynamic response optimization. Compared to the traditional optimal design’s result in a frame system, robust optimal design of the frame displayed a significant improvement in performance.

Abstract: Based on the operating characteristics of tracked vehicle transmission system, the dynamic characteristics and research methods for transmission system were summarized. According to the analysis of above, a new test rig which can simulate the steering process of tracked vehicle was proposed, and the methods for driving and loading system were determined, the test procedures and evaluation system for the tracked vehicle transmission system were summed up. It provides a practical test method for the design and development of tracked vehicle transmission system.

Abstract: Abstract: A dynamical analysis on a mass fixed at the tip of a massless flexible rod mounting on a rotating rigid body is presented in which the motion of the mass is kept in the plane of rotation as small deformation of the rod is assumed. For the rigid body undergoing a constant angular velocity the centrifugal forces and Coriolis force on the mass are considered. There exist two dynamic frequencies in which the first order dynamic frequency decreases with rotational velocity up to zero that is associated with a limit rotational velocity of the system. The motion trajectories of the mass in the rotational plane at different rotational velocities exhibit multiple traces with respect to the conventional line trace and may be split into the non-eccentric and eccentric portions. With a view on the change of amplitudes a critical rotational velocity is discussed.