Liu Chusheng

Motion simulation and interference checking of concentration-driven flip-flow screen

This paper briefly introduced the structure of concentration-driven flip-flow screen. Created a model of flip-flow screen motion simulation in Pro/ENGINEER, get the kinematic curve of midpoint of sieve plate, and compared the results with theoretical analysis, verify the feasibility of the design. Checked the motion interference of flip-flow screen, found a lot of problems during the movement of flip-flow screen, made some changes on two-dimensional drawings, reduce the cost of manufacturing.

Dynamics of 3-DOF spatial parallel manipulator with flexible links

The dynamics of 3-DOF spatial parallel manipulators with flexible links were performed. Firstly, a model of spatial flexible beam element was proposed, and the dynamic equations of elements and branches of the parallel manipulator were derived. Secondly, using the kinematic and dynamic constraint equations of the parallel manipulator, the overall system dynamic equations of the parallel manipulator were obtained by assembling the dynamic equations of branches. Thirdly, the dynamic responses of the 3-RRS parallel mechanism with flexible links were analyzed through numerical simulation. This paper can provide necessary information for the dynamic performance analysis, dynamics optimization design and control of the 3-RRS flexible parallel mechanisms.

Virtual prototype simulation of a 3-RRS flexible parallel manipulator

In applications where high structural stiffness, position accuracy, speed motion, and good dynamic performance are predominant requirements, parallel manipulators offer obvious advantages over serial ones. However, dynamic modeling and analysis of parallel manipulator, which are characterized by multiple closed-loop chains, are generally more complex than in the serial mechanism case. Especially, dynamic problems of the parallel manipulators with flexible links have not been studied as extensively. The primary goal of this research is the virtual prototype simulation of spatial flexible parallel manipulator. Firstly, the virtual prototype of a 3-RRS flexible parallel manipulator is established on the basis of the finite element software SAMCEF. Then, the displacement, velocity and acceleration of the 3-RRS flexible parallel manipulator are analyzed. The simulation results show that the flexibility of link has important influence on kinematics and dynamics performance of the flexible parallel manipulator.

Vibration analysis of a rectangular-hollow-sectional beam with an external crack

The vibration property of a rectangular-hollow-sectional beam with an external crack were theoretically and experimentally studied in this paper. The external part-through crack and through-thickness crack were considered. Linear elastic fracture mechanics were employed to establish the theoretical formula for computing the equivalent torsion spring stiffness of the two external cracks. Then, the experimental method of obtaining the equivalent torsion spring stiffness was developed. It is seen that the test data match fairly well with the analytical data. On this basis, the transfer matrix method was introduced to obtain the frequency equations of these cracked beams under three classic boundary conditions, and followed by the numerical method for calculating natural frequencies. Experimental tests on clamped–free beams were used to verify the accuracy. It should be noted that a part-through crack may lead to a more distinct natural frequency reduction than the through-thickness crack.

Kinematic constraint conditions and dynamic equations of spatial flexible parallel manipulator

The primary goal of this research is dynamics modeling and analysis of spatial parallel manipulator with flexible links. A new model of spatial finite element beam model is proposed. The kinematic constraint conditions of the moving platform and the branches of the spatial flexible parallel manipulator are derived. The dynamic model of the moving platform is developed based on the Newton-Euler principle. Then, using the kinematic constraint equations and dynamic model of the moving platform, the overall system dynamic equations of the parallel manipulator are obtained through assembling the dynamic equations of elements. Finally, the numerical simulation of a 3-RRS parallel manipulator was presented and compared with the results of SAMCEF software simulation. The results showed that the effectiveness and correctness of the dynamic models proposed in this paper.

Dynamic simulation of three-axis variable elliptical trajectory equal-thickness screen based on MATLAB

Introduction of a three-axis variable elliptical trajectory equal-thickness screen, according to Lagrange principle to establish the dynamic equations and make kinematics simulation using MATLAB software. Get the motion trajectories, vibrating direction angle, amplitude and throwing index of different points on screen surface. Through the analysis of these several parameters can be drawn that, vibrating screen in accordance with the method described in this article exercise can produce varying elliptical trajectory, is conducive to achieving equal-thickness screening.

Dynamic collision detection algorithm and application

Aiming at the problems of penetration and missing detection between particles with high speed in virtual system, a dynamic detection algorithm is presented which efficiency is advanced by the combination of multilevel detection and detection space division method in this paper. The algorithm has been applied in virtual sieving experiment system of discrete materiel and the results meet a good agreement with industrial experiment. It shows that dynamic collision detection algorithm can avoid the problems of penetration and missing detection between particles with high moving velocity and improve the precision of virtual sieving test. The algorithm is simple and with high efficiency which is suitable for simulation of complex virtual scene with large number of dynamic particles.

Dynamic simulation of 3-RSR flexible parallel robot

With the increasing requirements of high precision and high efficiency, the flexible parallel robot characterized by both the flexible robot and the parallel robot will be a new hot topic in robotics research. The primary goal of this research is the dynamic simulation of 3-RSR flexible parallel robot. Firstly, the virtual prototype of a 3-RSR parallel robot with flexible links is established on the basis of the finite element software SAMCEF. Then, the displacement, acceleration and equivalent stress of the 3-RSR flexible parallel robot are analyzed. Numerical results show that the flexibility of link has important influence on dynamics performance of the flexible parallel robot.