Advanced Materials Research Vols. 139-141

Abstract: Energy regenerative suspension can transform the shock energy produced in the driving process into electrical or hydraulic energy. This paper proposes a new hydraulic electromagnetic energy regenerative suspension design, and makes a comparison with the other two energy regenerative suspension designs by studying their structures and working principles, and makes an evaluation system by using fuzzy comprehensive judgment. According to the importance of the evaluating indexes, their subjective weights are gotten by using analytical hierarchy process (AHP); according to the performance statistics data, their objective weights are gotten by using entropy method; the general weights can be gotten from the subjective and the objective ones; and the evaluating value of suspension comprehensive performance can be calculated according to the general weights and the performance statistics data of evaluating indexes. The result reveals that the hydraulic electromagnetic energy regenerative suspension design has obvious advantages and is the most feasible design.

Abstract: Through analyzing the motion when motorcycle runs on the bump road, the 5-DOF multi-body dynamics model of motorcycle is developed, the degrees of freedom include vertical displacement of sprung mass, rotation of sprung mass, vertical displacement of driver, and vertical displacement of front and rear suspension under sprung mass. According to Lagrange Equation, the differential equations of motion and state-space formulation are derived. Then bump road is simulated by triangle bump, and input displacement is programmed by MATLAB. With the input of bump road, motorcycle ride comfort is simulated, and the simulation results are verified by experiment results combined with two channels tire-coupling road simulator. It indicates that the simulation results and experiment results match well; the 5-DOF model has guidance for development of motorcycle ride comfort.

Abstract: In order to analyze impacting characteristics of a metro vehicle, the impacting governing Eq. is established, in which, nonlinear stiffness and damping of a buffer, friction force between rail and wheel of the vehicles is considered. In terms of testing results, nonlinear stiffness and damping of the buffers is simulated. By numerical simulation, it is found that when moving trainset impacts standing trainset, because the impacting force, stroke of buffers located in impacting interface is the maximum, the capacity of the buffers must be large enough to avoid rigid impact; when trainset with different number vehicles impacts each other, the maximum impacting force is not only different from each other, but the stroke and energy dissipation of the buffers is also different; the capacity of buffers far from impacting interface may be small.

Abstract: The performance of HPS directly influences the comfort of vehicle, dynamic load of wheels and travel distance of suspension. In order to describe and evaluate the performance of HPS, the structure and working principle of main parts of the HPS are introduced and analyzed in this paper firstly. Then the physical model is founded by analyzing and simplifying the structure of HPS. According to the physical model, non-linear mathematical models of HPS with dual gas-accumulators are built up and a special program is composed. The results of computer simulation are carried out through the program. Then a testing rig for HPS is designed and manufactured after rebuilding cylinders and abundant experiments are performed on the testing rig. Comparisons are drawn between the results of simulation and testing, which manifest the mathematical model of HPS built in the thesis is feasible.

Abstract: For a certain type of automobile disc brakes, brake discs and friction linings were modeled by Pro/E. The dynamics simulations of braking process on disc brake were performed by the frictional contact algorithm and nonlinear finite element method. Distribution of stress, strain and displacement on the brake parts were investigated with different initial velocity. Analysis results shown that redistributions of stress and strain had occurred on the face of brake disc and friction linings in braking process. Meanwhile, the increased initial velocity resulted in increased stress and stain. Besides the stress concentrations appeared in brake disc role and friction lining corners at the beginning of braking, however, stress and stain became uniform along the braking. Analysis results provided the research of the optimum design and testing of disc brake with theoretic gist. And some improvement measures to the structure of disc brake were proposed.

Abstract: From a manufacturing viewpoint, the manufacturing tolerances of a hydrodynamic journal bearing system are inevitable. To examine and understand the effect of manufacturing tolerances on dynamic characteristics of a hydrodynamic journal bearing system can help engineers to confidently choose reasonable tolerances at design stage or to enable the system with certain manufacturing tolerances to operate closer to the theoretical predictions. This study presented a theoretical analysis method to determine and demonstrate the effect of manufacturing tolerances on bearing stiffness and damping, in which the concepts of limits, tolerances and nominal dimensions are introduced in. The results show that the manufacturing tolerances of a hydrodynamic journal bearing system have profound influences on the bearing stiffness and damping, and the magnitude of effect depends on system design parameters in the form of Sommerfeld number. The presented method will better predict system stiffness and damping characteristics.

Abstract: Rotor systems applied widely in industry are nonlinear dynamic systems of multi-degree of freedom. They must be not only stability but also have enough stability margins. Stability margins for different motion states in rotor systems are defined based on trajectory-based stability-preserving dimensional-reduction (TSPDR) in a quantitative stability analysis method for rotor systems. With the help of stability margin, dynamic behavior analyses of rotor systems become easy. In this paper, experimental method is used to validate definition and law of stability margin of quasi-periodic motion which was presented in above method. Experiment results in a rotor experiment rig show that regular pattern of stability margin of quasi-periodic motion calculated from measured data accords with the rule of above method. Therefore the definition and the law of stability margin of quasi-periodic motion described in the quantitative stability analysis method are valid in real rotor systems.

Abstract: Internal parallel moving gears transmission is a new type of planetary transmission with small tooth number difference. The dynamic model of the system is established by using lumped mass method. In the modeling process, the factors including the elasticity of all eccentric shafts, the elasticity of planetary bearing, the elasticity of supporting bearing on output shaft and the elasticity of meshing gears are considered, and the coordinate relation of the system is derived. The practical example and computer simulation was carried out and the dynamic characteristic is obtained. The results show that the gear transmission becomes steadier when simultaneously inputting the power from the three symmetrical shaft and utilizing multi-phase parallel mechanism, and the load of supporting bearing can be greatly reduced. This paper offers theoretical basis on correctly designing internal parallel moving gears transmission, reducing moving load and extending the service life.

Abstract: A new simulation method is proposed for dynamic characteristics of cracked rotor based on the finite element analysis, in which the stiffness model has been derived for the exact description of variation rules of cracked shafts. A non-linear dynamic equation is constituted according to stiffness characteristic of cracked-rotor change in time domain. Then the corresponding dynamic equation of the cracked rotor based on FEM analysis is modeled and the numerical simulation is carried out with solutions of high accuracy. At last, the dynamic characteristics of cracked rotor in diverse conditions are analyzed, and the simulation results are compared. It is shown that the non-linear oil film bearing force coupling with periodicity variety stiffness of cracked rotor has a great effect on dynamic behavior of the rotor and that the cracked rotor can be diagnosed effectively by the criterion that the swing of disk center obviously accretes and the wave crest appears when rotation speed is a half critical speed of rotor shaft system.

Abstract: The flow formulation was founded as console formulation, and with the body-fitted coordinate system and standard k - ε turbulent model, the numerical analysis of the internal 3-D incompressible turbulent flow of the agitated flow field was carried out by CFD software Fluent. The results showed that: the mixer impeller produced vortex jet flow, the constant velocity lines advanced as ellipse, the velocity along the centerline are larger than others, and utilized volume flow to transport the liquid. And, by changing some design parameters of mixer impeller, we can compare and analyze the numerical analysis results and find that: for the same impeller diameter, the mixer impeller whose hub/tip radius ratio is smaller has larger advancing speed in the agitated flow field, and the advancing speed is more evenly distributed, so the overall effect is better. Therefore, we should select the hub diameter of the submersible mixer properly.