Applied Mechanics and Materials Vol. 620

Abstract: Bench test and computational fluid dynamics (CFD ) simulation of the air pump loss on the 380 hydraulic retarder are completed in this paper . It turns out that the CFD simulation has nice reliability from the contrast of the air pump loss between the test and the simulation . And on this foundation , CFD simulation of two kinds of retarders with different turbulent structures is done . The contrast of the results of the simulation give the effects of different turbulent structures on cutting down the are pump loss .

Abstract: Abstract. To improve the flutter stability of a certain type fabricated steel truss bridge, a method of setting tuyere is put forward. Based on the two-dimensional 3 DOF coupling flutter method (2d-3DOF method), with the numerical wind tunnel established by computational fluid dynamics (CFD), the flutter stability control measures of tuyere is simulated. Through CFD numerical simulation, the flow field characteristics, flutter derivatives and critical flutter speed of origin and tuyere models are obtained. Through analysis, for the certain type fabricated steel truss bridge, the tuyere can improve its flutter stability. It illustrates the feasibility and reliability, and lays the foundation for further applied in practical projects.

Abstract: A rectangular vessel has two contact surfaces with different materials, iron and copper. In order to investigate thermo-structural characteristics of the vessel, the structural model is developed. The structural analysis is coupled with the thermal condition. The numerical simulation model with hex eight-node thermally coupled brick elements is established and solved by finite element method. The results show that the maximum stress with 112.5 MPa is distributed on the contact surface between the different materials. Because of the different materials’ expansions, there is stress concentration on the contact surface. The maximum displacement is 0.27 mm, almost the same at different pressure loads. The maximum stress increased to about 300 MPa as the temperature increase. The structural response caused by thermal expansion is important for the vessel design.

Abstract: In this paper, a new redundant degree-of-freedom wearable haptic device is developed and presented, which combines the advantages of the arm exoskeleton and the desktop haptic device. The haptic device has capabilities of large working space and high stiffness, the design of the wearable can reduce operators’ fatigue and increase the comfort of the operation. This paper also includes the analysis of workspace based on the kinematic analysis. Dynamics model of the haptic device has been established to get the torques of the driven motors of every joint. Lately, the virtual prototype model was established in ADAMS to get the simulations results, which lays the foundation for further force-feedback experiments.

Abstract: Based on Solidworks software, the three-dimensional model of two wheels scooter is set up. The finite element model of two wheels scooter is generated. Finite element analysis of telescopic mechanism of bar on two wheels scooter is investigated. The stress and strain of telescopic mechanism of bar is investigated. The stress diagram and the strain diagram are obtained. The method and the result can be used as a reference of innovative design of two wheels scooter.

Abstract: Inerters are two-terminal mechanical devices, which can simulate masses. It is significant to increase the ratio of the inerters’ inertance to its mass for mechanical networks synthesis. In order to increase this ratio, this paper proposes a novel mechatronic inerter which adds its own inertance by utilizing the electromagnetic torque of DC motor. An external electrical circuit of the mechatronic inerter is designed to ensure the additional inertance. The model of the mechatronic inerter is built and simulated. The results show that, under the same moment of inertia, the inertance of the mechatronic inerter is far greater than that of the mechanical inerter.

Abstract: Operation of the gun/turret system in a military tank is limited by several constraints some of which are posed by obstacles existing on the vehicle's own platform. In this study we tried to eliminate some of these constraints by the design and adaptation of transmission system between the chassis of the vehicle and the upper structure. The proposed approach is to adapt a motion platform on the top of the chassis of the vehicle. The motion platform chosen is a 3RPS parallel robot will achieve persistent control by allowing the upper structure of the vehicle to always back to the horizontal position and stay in a level position, in spate of the displacements and vibrations on the vehicle. The design of the chassis of the vehicle and the parallel platform is made using SolidWorks Computer Aided Design software. After that according to structural characteristics of the 3-RPS parallel robot, the mathematical model of the posture inverse kinematics is established. Based on Matlab software, SimMechanics, the simulation model of this robot is established. The validity of the inverse kinematics is proved by comparing the two models. And during the simulation, the related kinetics data and motion animate are obtained. Finally the simulation comparison after setting the parameters of the PID controller is established too, the animation shows that the control effect is obvious where the moving platform follows the desired trajectory.

Abstract: The properties of non-equilibrium turbulent boundary layers are substantially more complicated than that of equilibrium ones, and current understanding and predictive capabilities of the former are less well developed than of the latter. This paper proposed a nonlinear dynamical system approach to predict streamwise development of non-equilibrium turbulent boundary layers by means of realizing the closure of the momentum integral equation with aid of the modified log-wake law and the entrainment equation. The example calculation showed the results were in reasonable agreement with the experiment data, and demonstrated the proposed method could predict the streamwise evolution of the layers accurately and simply. Moreover, the method would be conveniently extended to the flows over rough surfaces.

Abstract: Marine salvage is a key link to ensure the safety of maritime shipping. Hydraulic dilator is one of the emergency tools which are widely used in rescue. The traditional hydraulic dilators with mineral oil drive or electric dilators can hardly achieve satisfactory results in underwater salvage environment. A kind of underwater salvage dilator with seawater hydraulic drive is designed. Its main functions, structure and the calculation methods of main parameters are introduced.