Applied Mechanics and Materials Vols. 215-216

Abstract: Permanent magnet linear synchronous motors (PMLSM) can serve as direct drive actuators for machine tools. However, PMLSM is more easily affected by load disturbance, force ripple and parameter variation. As a result, the design of an appropriate controller and research on dynamic performance are very important for PMLSM. In this paper, a feedback controller based on pole-placement is proposed to achieve desired tracking performance. The effectiveness and feasibility of the proposed method are demonstrated through theoretical analysis. The dynamic response and disturbance rejection ability for linear servo system were researched and the parameters which influence the dynamic performance of the system were discussed.

Abstract: In order to improve the applicability of the impact rammer, redesign impact rammer. In view of the different application requirements, change the length of impact rammer, redesign dynamic balance of impact rammer, or change the traditional tilted impact rammer to vertical type and reduce the impact rammer quality, make the new type impact rammer can work in more narrow and special space. The applicable scope of impact rammer is extended by the redesign of dynamic balance and the design of new type of impact rammer.

Abstract: From the view of flexible multibody dynamics, this paper considers not only Euler-Bernoulli beam assumption but also the effects of rotary inertia and beam’s inner tension, the equation of motion and associated boundary conditions of the dynamic model are derived by using the extended Hamilton’s principle. Converting the varying-time equation into a varying-coefficient differential equation in fixed region by substituting argument. And truncating the equation to a set of varying-time ordinary equations expressed by modal coordinates based on Assumption Modal Method and Galerkin Discrete Method. Then the equations were solved by using Newmark time integration method. The results show that moving mass excites mainly the first order mode vibration of beam. Before the moving mass disengages the beam, the dynamic effect of mass is so small that cantilever beam is lacked of obvious vibration. Its transverse displacement was mainly driven by static load. After the moving mass disengages the beam, the shorten length and shrinking movement of beam make the instantaneous vibration frequency continuously reduce and the vibration displacement gradually decrease too. While, at the same time, its total mechanical energy is increasing, so the beam is in unsteady vibration state.

Abstract: When walking robot MiniQuad-1 moves, the motion error is larger. The robot’s structure deformation is obvious. In order to improve the precision of the walking robot, the finite element analysis technique is adopted to research four-legged walking robot MiniQuad-1 in this paper. After the structure of the robot is introduced, the motion error of robot is discussed. The robot kinematics planning is completed based kinematics analysis. Some Motion postures are built using the solidworks. Static analysis of the motion pose is completed by using ansys software for robot MiniQuad-1. According to the analysis results, the robot structure improvement measures are determined. Further, the force and deformation for robot is studied after loading to lay the foundation for expand the robot of subsequent application.

Abstract: For the railway vehicles,flat damage on wheels is a very common defects,the sudden impact and vibration caused by flat damage on wheels endangers the wheels and the rail components a lot.The cause for flat damage on wheels,its physical characteristic, geometric representation,and its precaution are discussed in this paper,and applied to the Simpack multi-body dynamics software, a input form for flat damage on wheel was given.

Abstract: A harmonic response analysis was conducted on semi-hermetic refrigeration compressor by Abaqus software. The vibration displacement and acceleration response spectrums of the compressor’s key points were obtained. The vibration characteristics of the compressor show that the harmonic response analysis result is consistent with the experimental one. The vibration of the compressor at 50Hz is the most dramatic. The first trough in each direction is found around 70Hz, and after that each direction’s acceleration goes up significantly. At the same time, the conclusion verifies the vibration of compressor’s bottom corners by LMS Test. Lab Signature Testing. The paper provides a scientific reference for the further study on vibration and noise reduction in food refrigeration compressors.

Abstract: The purpose of this research work is to find the relationship between the movement and force (torque) of 3-TPS/TP parallel robot, the Lagrange method is adopted to establish the dynamics model, and the results of the simulation by ADAMS are given in this paper. The curve is about the change of force come from every joint of active chains with time. It provides a lot of data for further reference to choose the drive device.

Abstract: This paper illustrated the characteristics of parallelogram linkage，introduced the origin of the crank-group driving mechanism and its design principles, analyzed some problems of virtual constraints，and verified the feasibility of this mechanism.

Abstract: It is important to research the relationship between the lunar wheel and lunar soil in the circumstances of lunar surface in order that the lunar rover can work efficiently. Distinct Element Method (DEM) is an ideal method to analyze the relationship between lunar wheel and lunar soil. In this work, a prediction model for rigid-wheel and lunar soil is proposed, and the DEM model for lunar soil is found by the biax-test. The results show that the values of the simulation parameters in lunar soil are close to that of the real lunar soil after adjusting the micro simulation parameters. The Bekker’s model is used to calculate the pressure-sinkage, and the Janosi model is used to describe the shear characteristics. The plate-sinkage-test as well as the shear-test was simulated by PFC2D. The parameters of terra-mechanics were calculated based on the least square method. In the simulation, the value of K is 1635 kN/mn+2, n is 1.22 and k is 1.35 cm. After that, the soil bin system is simulated by the software PFC2D. Further, the tractive test which is checked out by the soil bin test and model calculation was simulated in PFC2D. Finally, by comparing the traffic ability of the nonrug-wheel with the rug-wheel, the results show that the slip radio is 0.52 of the rug-wheel and 3.21% of the nonrug-wheel under the traction load. The draw-bar pull is 121.67 N in the rug-wheel compared that of 7.71 N in nonrug-wheel under the slip is 10%.This indicates the rug-wheel can generate greater draw-bar pull and show better traffic ability than the nonrug-wheel under enough torque condition.

Abstract: To research the laws of barycenters of construction members of luffing system is significant. The kinematics of four-bar luffing jib multi-rigid body on portal crane is studied with mathematical matrix method which is convenient for programming calculation. These moving laws are concluded by visual software exactly. The mathematical formula which is the basis of modern design of luffing system is established. Then the cargo movement track and amplitude inertia force are counted handily. Matrix equation is verified by citing case study.