Abstract: In this article, author studied the application of two models of "single point damping-spring" model and "contact" model in the process of impact dynamic analysis. Research shows that the load and force could be transmitted smoothly in all these methods. But there still have limitations in two methods, we could not study the impact response of bearing itself and the shaft neck contacted with bearing in the "single point damping-spring" model, on the other hand, the penetration of contact parts could not be avoided completely in the "contact" model, sometimes, the numerical calculation even could not be converged if the parameters were not be set properly in this method. Of course, this two methods also have their own advantages, we could select different model according to different circumstances.
Abstract: In order to study the dynamic response characteristics of depressed center flat car with different velocity, based on multi-body system dynamics software SIMPACK, 320t depressed center flat car system rigid body and rigid-flexible coupling-body dynamics model were established and the dynamic response simulation analysis of empty and loaded flat was carried out under several velocities. Then maximal vertical vibration displacement amplitudes and vertical vibration accelerations of depressed centre flat frame under different velocities were obtained. It showed that the maximum accelerations and displacements amplitudes increase with as the speed gradually increased for both empty and heavy vehicles and the trends are similar for the rigid body or rigid-flexible coupling-body. But the values of rigid-flexible coupling-body are bigger than that of rigid body because the elastic vibrations from the depressed center flat frame and all levels of suspension contribut to the vertical displacement. As the speed increases, the vertical displacements of the rigid-flexible coupling-body and the elastic ones response synchronously. The vertical displacements of the empty and heavy vehicles reach their peak values at different speeds and the elastic displacement also has a large proportion, which shows that there are larger elastic vibrations at the speeds. Therefore, it is not suitable for the depressed centre flat to run at very high speeds, and the speed should be confined.
Abstract: The refrigerator door cover deformation or cracking is a major flaw in the BCD268 refrigerator. In this paper we create a simplified model of the refrigerator door. Based on the standard modules of ABAQUS finite element analysis software, this paper analyzed the deformation mechanism of the refrigerator door, and determined the parts of the deformation. Aiming at the deformation and cracking, the numerical simulation of BCD 268 door cover was conducted, and two kinds of different options to strengthen the ribs were proposed, then the two programs were carried out through finite element analysis, and prototypes were fabricated high and low temperature impact test for validation. Optimal structure scheme was verified by contrast. The designed lower-door covers were produced in small scale, and it proved to be consistent with the numerical results of finite element.
Abstract: The UFD method was used to analyze the flow field in the swirl atomizer whose geometric structure had been designed with ideal theory algorithm. RNG (Renormalization Group) k-turbulent model was applied to the numerical simulation of the flow field, and SIMPLE algorithm was used to solve the finite difference equations. Through the analysis of pressure and velocity fields get by the numerical simulation, we found that the use of CFD method in the swirl atomizer design is beneficial for getting more detailed and accurate flow structure and advantageous to analyze the influence of different nozzle geometry, and then given a reasonable design opinion.
Abstract: Large-scale rotary kiln drive system model is created based on virtual prototyping technology and ADAMS. After analysis of the actual working conditions, system constraints are added to the rotary kiln model, and kinematic analysis to be process. At last, kinematics curve consistent with the theoretical analysis on the model of the rotary kiln drive system, which verifies the built rotary kiln drive is correct. This kinetic analysis is ready for the follow dynamic analysis.
Abstract: This paper mainly researches the control system of honing machine spindle reciprocating motion. On the basis of brief introduction to the processing of honing machines, its mathematic models were established, and design the double control system on the base of fuzzy control .Two fuzzy controllers were used separately according to actual error signal of the system output to improve the system rapidity and overshot .so that make the designed control system of honing machines spindle reciprocating motion can satisfy the design requirements better. Finally the control system was conducted by using the tool of MATLAB. The simulation result showed that the double fuzzy controller can effectively reduce steady-state error of the system and overshoots can well satisfied the system performance index, and has some quick response ability.
Abstract: The hydrodynamic characteristics of bodies are greatly affected by cavitation. Coupling with natural cavitaion model, a multiphase CFD method is developed and is employed to simulate supercavitating and partial cavitating flows over axisymmetric bodies using FLUENT 6.2. The results of supercavitation of a disk cavitator agree well with the boundary element method (BEM), the analytical relations and available experimental results. The present computations and the BEM results are compared with experiments for partial cavitating flows over three typical axisymmetric bodies and the results are discussed. Limitations are on the pressure prediction in the cavity closure region for the BEM, although fairly good quantitative agreement is obtained for three axisymmetric bodies at most of cavitation region. The present computational model on cavitating flows are validated, offering references and bases for hydrodynamic researches.
Abstract: The piston skirt and cylinder liner is a coupled contact model, It is of great importance to analyze the contact stress and deformation. Due to the existence of the gap and the lateral clap force between piston skirt and cylinder liner, which leads to the lateral movement. According to the secondary movement and hydrodynamic lubrication theory, the maximum lateral clap force can be obtained in a working condition, before piston crosses TDC, the huge gas pressure makes the piston skirt and cylinder liner collision contact, and creates the enormous clap force, which can aggravate the noise and vibration between piston skirt and cylinder liner. We would set maximum lateral clap force as a dangerous condition, which can be loaded on the contact model. By the means of nonlinear software ABAQUS, to establish the piston skirt and cylinder liner contact model, and analyze the contact stress and deformation.
Abstract: Italic textIn this paper, the reduced-order model (ROM) of unsteady compressible flow based on POD-Galerkin projection has been investigated. The Euler equation formulated with the conservative variables for compressible flow has been reformulated using modified primitive variables. The POD modes are computed using snapshot method and then an explicit quadratic ROM is constructed by applying the Galerkin projection to the modified Euler equation. Because of lacking any dissipation in POD-Galerkin projection, the flow calibration method is introduced to account for the numerical dissipation to stabilize the ROM. At last, the NACA0012 airfoil undergoing pitch harmonic oscillating in Mach number Mach = 0.755 is calculated as a test case. For this flow configuration, the calibrated coefficients of the ROM are almost the same as the initial guess which comes from POD-Galerkin projection; the differences are mostly focused on the linear Lij coefficients and quadratic Qijk coefficients.
Abstract: To achieve high performance tracing control of the three-links spatial robot, a fast terminal fuzzy sliding mode control method is proposed in this paper. Firstly, the control method can efficiently solve the singularity of the controller through switching between terminal sliding mode surface and linear sliding mode surface. Secondly, to diminish the chattering in the control input, a fuzzy controller is designed to adjust the generalized gain of fast terminal fuzzy sliding mode controller according to fast terminal sliding mode surface. The stability of the control algorithm is verified by using Lyapunov theory. The proposed controller is then applied to the control of a three-links spatial robot. Simulation results show the validity of the proposed control scheme.