Advanced Materials Research Vols. 706-708

Abstract: Abstract A multi-body dynamics calculation model for air suspension guide mechanism of car is established, which analyses the motion model and its application of guide mechanism on car double wishbone independent suspension by using the basic theory of rigid body motion, and then carries out kinematics analysis to make the design work rational, simple and accurate. The establishment and optimized analysis of the structure parametric design model, which is used for the objective function of minimum variation of the caster angle, kingpin inclination angle, wheel camber, wheel toe-in angle and wheel tread, gets the reasonable and optimization design scheme of structure parameters for air suspension guide mechanism, and provides a theoretical basis for further improvement of this automobile suspension system.

Abstract: Established the precise model and completed the virtual assembly of CVT with diclinic cam plate synchronous revolution and internal power shunt application of Pro/E software basing on the transmission principle. Obtained the displacement, velocity and acceleration time-dependent curves of nine plungers centroid through the simulation of transmission operation, based on the simulation analysis gaining that the transmission does not exist in dynamic and static interference, and the structure design of CVT is reasonable. Completed the processing of CVT manufacturing, experiments are carried out to verify the simulation analysis of the transmission of real.

Abstract: Structure of one hybrid mono-directional magnetic spring was presented. Based on the experiment rig of magnetic spring the stiffness properties and its influencing factors were experimentally studied and analyzed. Research results show that the stiffness of the hybrid magnetic spring composed of the electromagnet and the permanent magnets is adjustable and controllable. As a whole the axial magnetic force of the magnetic spring increases non-linearly with the air gap between magnets decreasing, but within small air gap when there is considerable difference in magnetic flux density between the two magnets the axial magnetic force will decrease with the air gap decreasing, namely the magnetic spring behaves negative stiffness characteristics. The axial magnetic force is decided by the magnet with less magnetic field energy. And the adjusting range of axial magnetic force depends on the two magnets dimensions, their surface magnetic flux density and the magnetic saturation degree of the electromagnet. Furthermore, under same air gap the axial magnetic force of the magnetic spring increases linearly with the excitation coil voltage increasing.

Abstract: Vibration is one of the key factors affecting the machining precision of ultra-precision grating-ruling machines. In this study a structural model of the ultra-precision two-stage isolation system of a large grating-ruling engine is designed according to the vibration characteristics of the grating-ruling engine, and an active vibration control system adopting the fuzzy adaptive PID controller (FAPIDC) approach combined with an air-springs system is applied to realize high performance in controlling complex micro-vibration. The stability of PID control and the flexibility and adaptability of the fuzzy logic controller (FLC) are both combined for FAPIDC, because the optimal values of PID parameters are obtained by using fuzzy sets. The simulation results confirm that the two-stage vibration control system using fuzzy adaptive PID control strategy has good isolation performance against disturbance. The control system has fast dynamic response, high stabilization precision and strong adaptive robustness.

Abstract: Based on topology optimization, modal analysis and lightweight design of high-power marine gearbox case is studied. By the finite element analysis of original gearbox case, the structure strength has greater redundancy. After determining the design space and working load, after determining the design space and working load, the case thinning and local strength enhanced program based on SIMP method has determined. By considering the rationality and security of design and manufacture, both the static and dynamic performances of the optimized case is greatly improved, with a 16.36% reduction in maximum stress, a 13.86% reduction in maximum displacement, and successfully saving material 5.87%.

Abstract: In this thesis, PT7032 tower crane was taken as the research object, and the modeling and modal analysis of the overall structure were carried out using Abaqus software. The low-order natural frequencies and main vibration modes of this tower crane were obtained based on the above modal analysis. The analysis results will prevent the tower crane from working on resonant region, and will make preparations for the following dynamics response analysis of the tower crane.

Abstract: To study the natural vibration characteristic of gun systems, the rigid-flexible coupling multi-body modeling method for gun system was developed. Using multi-body theory the rigid-flexible coupling chain structure of gun was established firstly, and the dynamic equation in closed form of gun system during launching was provided by Lagrange’s method of the second. Based on above, the analytic expressions of eigen-value equations for gun system were presented. And using that, the natural vibration frequencies of gun system were calculated, and the natural vibration characteristics were analyzed. The analysis indicates that the calculating results achieved using rigid-flexible coupling modeling method are more close to the experimental results compared to pure rigid modeling. Therefore it is essential to consider the flexible deformation of barrel if we want to acquire the natural vibration characteristic of gun system more accurately. Furthermore, the investigation in this paper also shows that the rigid-flexible coupling multi-body modeling method is an effective method for the dynamic analysis of gun system, and can be used to research the dynamic characteristic of other mechanisms as well. The model, method, and results presented in this paper have significance to correlative engineering research, and provide a new technical way for improving on the design of gun.

Abstract: The slab track is the main structure of the high-speed railway track, the Inherent dynamic characteristics of which is of great significance to the research on the Vehicle-Track Coupling Dynamics. The assumptions of the modal function describing the natural vibration of the track is a necessary theoretical basis in analytic and numerical calculations for dynamics problems, which is more in accordance with the real situation, the more likely characteristic estimation are to be accurate. In this paper, with the method of combine matrix, the system characteristic equation of slab-track model is deduced, and the exact analytic formulas of frequency equation and modal function are obtained. Meanwhile the specific effects of the Rail longitudinal force on the vibration performance of the tracks are analyzed through instances. The results show that this approach is an effective analytic method, the solution of which is accurate. And the track parameters can be flexibly initialized, which is especially applicable for the condition of track parameters varying and longitudinal strain with distribution.

Abstract: The Secondary flow in a curved duct of square cross-section, is investigated numerically using the spectral method. The walls of the duct except the outer wall rotate around the centre of curvature and an azimuthal pressure gradient is imposed. Multiple solutions are obtained at the same flow condition. It is also found that the secondary flow in a cross-section consists of two-vortex, four-vortex, eight-vortex or even non-symmetric vortex with respect to the centre line of the cross-section. The linear stability analysis for the multiple solution is also carried out to investigate the actual flow patterns.

Abstract: In order to improve the block area and damage probability to targets, a new type warhead of circumferential cutter is presented. The optimization simulation is designed for the circumferential cutter warhead by using LS-DYNA finite element software. The detonation mode and the liner curvature radius are two important factors, which influence the formation process of circumferential cutting warhead. The result shows that priority should be given to use the upper and lower ends at the same time blasting technique. The shaped charge liner curvature radius and shot elevation ratio should be controlled in between 0.9 and 1.1.The warhead can be envisaged to achieve the desire of circumferential cutting.