Applied Mechanics and Materials Vols. 80-81

Abstract: A prototype of a Multifunctional Solar Assisted Heat Pump (MSAHP) system is designed in the study. The system integrates a heat pump water heater, a conventional air-conditioning unit and a solar water heater, and takes advantage of their multiple functions in terms of solar and heat pump water heating, space cooling only, space cooling integrated water heating, and air-source/water-source heat pump space heating. The principle and different operating modes of the system are presented. The experimental study of the prototype of the MSAHP in the space cooling integrated water heating mode was conducted. The results indicate that the combined energy efficiency ratio (EERc) of the system fluctuated between 3.39 and 6.20 in this mode. Experiment was also conducted to test the relevant performance functions of the system in the space cooling only mode. The results show that the energy efficiency ratio (EER) of space cooling only mode is 2.61.

Abstract: The modern design method based on the finite element theory has become the essential means of present machine design. In this paper, dynamics finite element model of NC grinding machine tool’s bed has been established with the finite element analytic technique. Dynamic characteristic of processing has been studied. The optimization program of structure to lower the vibratory response has been designed. This advances the dynamic stiffness of bed. This research provides an essential theory and technology support for achieving the advanced level of the international similar machine tool on the aspect of machining precision, reliability and security.

Abstract: Based on the computation method of reliability in limit state theory, the paper analyzes sensitivity of gear reliability with the change of various random factors. Taking the reliability computation of circular gear as an example, it systematically calculates the change of gear reliability with the change of average value and RMS error of random variables. Based upon the computed result, it analyzes and finds out sensible random factors that have larger influence on gear reliability for the convenience of strict control of gear design, manufacturing, use and maintenance in future in order to guarantee the requirement for gear reliability. Computed result in this paper can be used as reference for the study on gear reliability in future.

Abstract: The extension control is a newly developed intelligent control method used to solve control problem from information transformation presented based on extenics. Firstly some basic concepts about extension control were introduced, on this basis, the extension control algorithm was improved and the extension control was applied to pump-control electro-hydraulic servo system. The simulation and experimental results show that the pump-control electro-hydraulic servo system based on extension control has such advantages as quick and stable response, simple parameters determination and excellent dynamic quality, with a better prospect for development.

Abstract: According to GB 20071-2006 regulation, the finite element model of aluminum honeycomb block was built with beam elements, and the corresponding moving deformable barrier (MDB) model was validated. Side impacts between a vehicle and the MDBs which were set up with beam elements and solid elements respectively, were simulated. The velocities of five key points on the B pillar and the door were measured and compared with the test data. The results show that the demands of the regulations could be achieved by the MDB with beam elements, while at the same time, the efficiency of computing is improved and better local characteristic is obtained.

Abstract: The stroke and the material characteristics of the large five-axis machining center were expounded; a structure similar to the truss of the reinforced beam plates was designed according to the design requirements of the beam structure, this structure could make the frame gain high rigidity in small size, the frame made by the rods could be constituted with high rigidity, the overall rigidity of the machining center could be improved 23% - 25%; three different beam structures were designed, and the finite element analysis software ANSYS was carried out to analyze their static characteristics, the maximum deformations in three directions X, Y, Z were obtained; compared with other structures through the comparisons on mass, stiffness and performance, the optimal structure was obtained, its mass was 1818Kg, and its maximum deformations in X, Y, Z directions were 0.45mm, 0.07mm and 0.13mm, respectively.

Abstract: To solve the braking problems caused by train speed-raising, shorten braking distance and avoid probable wheel sliding arising therefrom, we launch a research into Aerodynamic Brake and design an aerodynamic brake mechanism, the wing plate of which can open and close bilaterally against the wind with opening angle controllable. Kinematic analysis and optimization design by using ADAMS are done in order to reduce the driving force and obtain more reasonable structural parameters. Research in this mechanism may provide important referential value for high-speed train braking technology.

Abstract: In this study, the hot forging process of spline hub was simulated using the finite volume method. The proposed simulation model was compared with experimental samples and approved. Then, stress analysis of the rigid die was undertaken using the finite element method. On the basis of proposed model, the full factorial design of experiments was performed for investigating the influence of forging temperature and flash thickness on the die fatigue life. Results show that the increase in forging temperature and flash thickness, both cause the increase in the fatigue life. It is also shown that the effect of forging temperature on the fatigue life is greater than that of flash thickness. In drop-hammer forging, when number of blows decreases, the die fatigue life increases considerably.

Abstract: Formation of chip is a typical severe plastic deformation progress in machining which is only single deformation stage. The large strain, low temperature and deformation force are the major premises to create significant microstructure refinement in metals and alloys. A finite element method was developed to characterize the distribution of strain, temperature and cutting force. Effects of rake angle, cutting velocity and friction on effective strain, cutting force imposed in the chip are researched and the conditions which lead to the large stain deformation in machining are highlighted. The results of simulation have shown that chip materials with ultrafine grained and high hardness can be produced with negative tool rake angle at some lower cutting velocity.

Abstract: Macpherson front suspension model was established by ADAMS/CAR software. The simulation of the parallel wheel traveling and the dynamic analysis of suspension was carried out when the vertical stiffness of tire is 170N/mm and 190N/mm, respectively. Simulation result shows that the enhancement of the vertical stiffness of tire has no influence on the alignment parameters of the front wheel of suspension, but can increase the arm of force of kingpin caste and the stiffness of suspension, decreases the dive, lift and scrub radius, improve the steering returnability and the handling and stability. Analytical result can be used to direct the design of the suspension and tire of automobile.