Advanced Materials Research Vols. 753-755

Abstract: Actuator is widely used in the control system. Among all characteristics of an actuator, dynamic stiffness is an important indicator; it must satisfy the requirement to inhibit the control surface’s flutter. This article described the definition of dynamic stiffness of actuator, introduced the importance of the research of dynamic stiffness of actuator, designed a test bench for dynamic stiffness testing and putted forward a method which based on Programmable Logic Controller to simulate a signal generator which generated sinusoidal signal load to test the dynamic stiffness of actuator, found out a worst point of the actuator’s dynamic stiffness, improved the stability of the actuator system and avoided the occurrence of flutter at the frequency.

Abstract: As for the two typical inputs of pure side slip angle and pure yaw angle, this paper presents the in-depth analysis of lateral force, aligning torque and relaxation length respectively within the domains of distance and spacial frequency, and also explains the test results by theoretical model. Within the small side slip angle, tire is a first-order linear system. Relaxation length is equivalent to the time constant of linear system, which decreases as slip angle increases. It indicates the dynamic performance of tire system.

Abstract: A type of bogie structure was proposed for the eight-axle locomotive, of which the middel bogie forme was used to connect the two B0 bogie and support the car body with three suspensions. A single drawbar connect the B0 bogie and car body directly to transfer the longitudinal forces. This structure is simple and feasibility, which can achieve high adhesion availabillity and good dynamic performances. Three suspension can achieve a excellent stability of car body. Comparing with a same speed and axle load class 2C0 locomotive, the wheelset lateral force and wheel rim wear factor are reduced by about 35% at the R300m small radius curves, and the wheelset lateral force is decreased by 15%, and the rim wear factor is reduced by 23% at the R800m curves.

Abstract: Wheel-rail contact provides interface between moving vehicles and track system. Wheel-rail contact affects strictly vehicle motion, which it depends on the geometry profile of the wheel and the track, the materials and the working circumstance. The paper describes in detail trace method, three-dimensional projection profile method, and compares them with result from Adams RSGEO when calculating wheel-rail straight contact geometry. The result shows that radii difference of rolling circle keep in same when wheelset displacement is under 7.5mm. But there are many difference when wheelset displacement exceed 7.5mm, and result from three-dimensional projection profile method more approached one from Adams RSGEO.

Abstract: A lateral-torsional coupled vibration model of the slewing mechanism of a hydraulic excavator is developed with consideration of the effect of lateral vibration and torsional vibration of sun gear and planetary gear on mesh displacement, the mesh stiffness of gear pairs, the bearing stiffness of the planetary and the coupling relationship of two stage planetary gear trains. The dynamic response of the slewing mechanism of a hydraulic excavator is obtained. Compared to the pure torsional vibration, the lateral-torsional vibration model is more reasonable.

Abstract: Direct at NC machine tool feed system, the article analyzed the influence of the nonlinear friction at each motion joint, and points out that the nonlinear friction are the main factors that influence the positioning accuracy of the feed system. The article have discussed the methods for effectively compensation and controlling of the nonlinear friction respectively from two aspects of flutter compensation and predictly controlling the nonlinear friction, and proved the correctness of the compensation and control method that is proposed in this paper.

Abstract: This paper discusses the design of a section morphing wing that permits a change in the wing section while simultaneously supporting structural wing loads. Section morphing wing allows for two discreet airfoil of the wing. The airfoil 1 is original airfoil maintained by NACA 4412 rib sections. The section morphing wing uses shape memory alloy spring actuator to drive wing section deformation. Skins of the section morphing wing uses shape memory polymer. Computational aerodynamics are used to estimate the performance and dynamic characteristics of each wing section of this section morphing wing as its wing section is changed. Results show that when angle of attach (AOA) is 0 deg, the lift-drag ratio decrease as the airfoil thickness decreases when mach number is less than 0.9 and the lift-drag ratio increase as the airfoil thickness decreases when mach number is greater than 0.9. When AOA is 5deg, the lift-drag ratio increase as the airfoil thickness decreases . The lift-drag ratio decrease as the airfoil thickness decreases when mach number is less than 0.7. When AOA is 10deg, the lift-drag ratio increase as the airfoil thickness decreases when mach number is greater than 0.7. We can chose airfoil 1 or airfoil 2 according to variation flight conditions.

Abstract: Along with the development of environment test technology, experiments of containers with not full liquid has been possible to be carried out. The particularity is that the liquid surface will slope as the rotate speed of centrifuge increasing, so that, the rising of liquid centroid causes the change of centrifugal moment of inertia which is generated by the liquid. On the other hand, the balancing mass is invariable. So unbalanced torque moment acting on the trunnion of suspended basket is brought. It will cause accident or damage of equipment. The method of analyzing dynamic balance for experiments of conglobates container with not full liquid is proposed. The function of unbalanced moment and acceleration can be educed. The optimal project of counter-balance mass is determined by mathematical solution of function maximum and using figure of function. The simplified formula is concluded.

Abstract: Harmonic components in holospectrum are mainly due to the lateral vibration, and they are important parameters in fault diagnosis of rotating machinery. However, defects on measuring shaft surface are also included in harmonic components in holospectrum and may lead to misdiagnosis. It’s necessary to study a method to identify the shaft surface defects. Based on the manufacturing process of outer round, this paper studies the forming mechanism of harmonic defects on outer round and their characteristics in holospectrum. An experimental example is also given to validate the theoretical analysis, and the results show that holospectrum can recognize the harmonic defects on outer round well.

Abstract: The far-filed approximation solution was derived in a closed formula by using Fourier transform method. Two kind of possible concentrated forces, a line force, a point force, were included in the analysis. Moreover, a parametric study was carried out to clarify the effect of the incentive loading position and the various physical characteristics parameters of the rectangular plate. Conclusion is drawn that, the far-filed pressure level decreased with external excitation approached to the edge. Through analysis on far-filed sound pressure level, that can give foundation of designing acoustical elements and active noise control.