Applied Mechanics and Materials Vols. 490-491

Abstract: Aiming at the attitude interference of space mechanical arm of free-flying space robot (FFSR) against the satellite body, parallel coordination motion control technology for space mechanical arm and satellite body is proposed in this paper. Firstly, the position and velocity at any point based on FFSR system can be expressed as a set of functions consisting of chain pole centroid vectors, and the kinematic model for FFSR has been set up. Secondly, the compact form of dynamical model in system centroid vector function for FFSR is set up with Lagrange method. Finally, inherent redundancy characteristic of FFSR system is applied to propose the parallel coordination motion control technology which simultaneously and effectively controls the motions of F satellite body and configuration of space mechanical arm. Transposition Jacobi controller with inertia feedback has been developed.

Abstract: Floor vibration model was established by FEM and the modal analysis was conducted, which were based on the condition that this experiment took the automobile floor as the research object and applied the basic theory of finite element analysis. Simultaneously the results of modal analysis were compared with the results of the experiment, verifying the accuracy of the model. This can be considered as a basis of providing reference for the optimization and improvement of light bus floor.

Abstract: To improve the transversal stability and lateral stiffness, this paper develops a new type of pneumatic single bending joint. When supplied the air pressure, the joint bends under the action of the bending moment generated at the end of the joint. The bending experiments have been done on the static experimental device and the relation between the bending angle of joint and the air pressure is acquired. The study of this paper laid the foundation for further application of the single bending joint.

Abstract: During the past decades, increasing requirement in aircraft for high-performance, lightweight structures have caused strong interests on the development of fiber-metal laminates (FMLs), which are manufractured from thin layers of glass fibre reinforced composite and alluminium alloy. In this paper, the nonlinear dynamic response problem of the FML plate subjected to unstable temperature with interfacial damage is analyzed. Based on the weak bonded theory, the interfacial constitutive relations of the FML are constructed. According to the Hamiltons variance principle, the nonlinear motion equations of the FML with interfacial damages subjected to the unstable thermal field are obtained. And then, the finite difference, Newmark-and the iteration method are applied to solve the nonlinear motion equations. In the numerical examples, the effects of the interface damage, the amplitude and frequency of imposed loads and the temperature fields on the nonlinear dynamic response of the FML plates are investigated. And in conclusion, the effects of various type of temperature on the nonlinear dynamic response of FML plate are different obviously.

Abstract: Micro vibrations, produced by reaction flywheels, coolers, driving motors and other moving parts in spacecrafts, will result in jitters and performance degradation of sensitive optical payloads, such as laser communication platforms, space telescopes and staring cameras. In this paper, one hexapod platform with flexible ball joints is employed to suppress vibrations and steer the payload in 6-degree-of-freedom (DOF). At first, dynamic modeling of the flexible hexapod platform with two-stage hybrid isolation struts is derived. Then, a composite control strategy is proposed for vibration isolation and precision tracking. Finally, the simulation study is presented to validate the proposed control strategy.

Abstract: Three-stranded polyethylene ropes and twines are widely used as one of the main materials for fishery facilities. The shape and performance of the net fishing facilities in water are determined by the hydrodynamic properties of these ropes and twines. In the present work, experiment investigation was made in the flume tank in Tokyo University of Marine Science and Technology. Five kinds of three-stranded polyethylene rope with different sizes of diameter were tested. Drag and lift forces, together with sideways force acting on ropes under various trial conditions were measured by underwater load cells which were independently developed by the authors to record three axial force components. The drag, lift and sideways forces per unit rope length, under various attack angles at several flow velocities were obtained through data analysis. Then the drag coefficient, the lift coefficient and the sideways force coefficient were calculated within the range of Reynolds number R_d = 2.5×10³~3.0×10⁴. The following conclusions may be made from the experimental results: (1) At all the three testing attack angles i.e. 45o, 60o and 90o, the drag per unit rope length is proportional to the square of flow speed; (2) As the attack angle equal to 90o, the drag coefficient can be expressed in a power function of Reynolds number as given below: It can be inferred that the drag coefficient is approximately equal to 1.4 in the automatic model region, i.e. 1.2×10⁴ < R_d < 3.0×10⁴. (3) As the attack angle equal to 45o or 60o, the lift force per unit rope length is proportional to the 2.5^th power of flow speed and the lift coefficient has a similar trend as the drag coefficient. But the lift coefficient makes smaller fluctuation compared to the drag coefficient when tending to a constant value in the automatic model region, i.e. 1.2×10⁴< R_d <3.0×10⁴.

Abstract: Paper had to be removed at authors request

Abstract: As one of the critical components of the steam turbine, the security of turboset is directly affected by the reliability of the blade. In this paper, taking the governing stage blade of a large-power steam turbine for example, the thermal elasticity stress and deformation of the blade were analyzed under the action of airflow force,centrifugal force and temperature load. Then the Norton model was adopted to simulate the blade creep process of 100000 hours and the stress and strain of the blade were obtained.

Abstract: This paper makes a strength verification of the chief components of a new hydraulic motor to find out that the design of this new motor meets every standard and this finding will lay a solid theoretical ground for relative experiments.

Abstract: Based on the analysis of a typical elevator for car hydraulic system, a general modular simulation model is established. Through the case study of initial cavity volume and load change different effects on the dynamic performance of hydraulic system, the conclusion is found that the increase in initial cavity volume and load are conducive to reducing the hydraulic impact at the starting moment, but have an adverse effect on the dynamic performance at the stopping moment, and that the time to reach the steady state increases.