Applied Mechanics and Materials Vols. 121-126

Abstract: For the need to test square wave pulse sequence, designed and implemented a recorder. Recorder using FPGA for judging square wave pulse’s edge and precise timing functions, using C8051F MCU to storage the results of time-series data and printing functions, FPGA and MCU using a custom protocol for data exchange and command transfer. After experimental verification, the recorder have 1ms accuracy to record 28 roads square wave pulse signal timing, and fixed-format print the results.

Abstract: This paper discussed three schemes to obtain vibration modal frequency. First, theoretical numerical method was introduced to simulate the vibration modal by ANSYS software. Second, one kind of traditional experimental modal analytical scheme was designed to obtain modal frequency by computer random signal and vibration analysis system (CRAS). Third, a new experimental modal test scheme was proposed by FBG test platform. A completed case on modal frequency of the cantilever was carried out by three different schemes, in order to evaluate their merits and drawbacks by comparison. Accordingly, computational modal numerical method in combination with experimental modal test method can meet the analytical demand of modal parameters in practice engineering.

Abstract: Taking the composite rubber suspension of a 6×4 heavy vehicle as research object, an accurate finite element model for the composite suspension at loading states is firstly built with consideration of nonlinear contact between spring leaves, and then a new finite element approach for calculating and analyzing static mechanical properties of the composite rubber suspension. Finally, the stress distribution and deformation is analyzed under different loads by using Hypermesh software and the results can be applied to its strength design. And moreover, some primary principles of the composite rubber suspension stiffness and displacement changing with different loads are obtained, which provides reference basis for virtual design and lightweight design of the vehicle composite rubber suspension.

Abstract: Copper and aluminium alloy could be welded by friction stir welding (FSW) but it is quite difficult to achieve a defect-free welding joint for welding dissimilar materials because of the enormous difference of their thermo-physical performances. In this paper, another friction stir tool was applied as a heating source to preheat the copper side to 150~200°C in the welding direction. Preheating temperature can make up the lost heat, improve the temperature of copper plate before the FSW process, achieve the refining grains, and then obtain a high quality welding joint. We concentrated on hybrid heat-source equipments design and procedure optimization in our studies. The microstructure, mechanical properties and phase constituents of FSW joints were studied through mechanical test and metallographic analysis. The results indicated that the hybrid FSW technology with preheating for copper T2/aluminium 5A06 dissimilar materials can not only improve the welding efficiency, but also obtain the high quality welding joint. This special welding technology could solve the welding problems of Al-Cu dissimilar materials and had a good potential for application in aerospace manufacturing.

Abstract: In order to prevent the locked rotor, step-out and super ledge speed control of step motor, speed-up and speed-down control to the step motor should be carried out. Based on the speed -up curve analysis, using of symmetrical design, this paper has simplified the speed-up and speed-down curve. In order to achieve real-time computing exponential curve in SCM, using the method of constant duration and control pulses, speed-up and speed-down control, exponentially, are achieved, and, the connections between step motor and drive and circuit have been designed.

Abstract: By a reasonable transition of the meshing equation and the contact line equation based on the principle of spatial meshing, using matlab numerical calculation and graphical function to draw a diagram of modification parameters and contact line of worm gear. Proposing a fast and accurate method for distinguishing the type of contact line. For further analysis of worm gear meshing performance provided a useful value.

Abstract: The quality question of deep cavity shell was the wall thickness, its influence factors, together with the product structure, die-structure, technology and other factors. The reasons of molding the wall with a thick beyond tolerance were discussed from products design, molding equipment and die, forming technology and material properties for a comprehensive analysis, and the corresponding resolution methods were presented.The methods of the adjustment of a cavity molding were introduced.

Abstract: With the development of component technology and component library expansion, component representation and retrieval technology as the component library management two core technologies has become a research hotspot. According to the current widely used methods described and characteristics of components faceted classification, this paper starting from component reuse by different search methods，based on view search method、based on faceted search method、based on terms retrieval method three kinds of term component retrieval methods and the corresponding model of the five matches and two matching algorithms are proposed. Theoretical analysis and experimental results show that the three kinds of retrieval methods used in large-scale component library component retrieval, to meet the component reuse of various search requirements and the retrieval efficiency is feasible.

Abstract: In this paper, a semi-active impact control system, which consists of a new Magnetorehological elastomer (MRE) absorber with variable stiffness, is proposed and its vibration control with impact load is investigated. An impact testing platform is established and mechanical property of fabricated MRE is tested. Based on Newton’s law the appropriate mathematical model of MRE absorber system is established. PID controller for MRE absorber system is designed to reduce the effect of impact load. Finally, the effectiveness of control strategy is verified by numerical simulation.

Abstract: In order to evaluate the threat level of air targets objectively, based on comprehensive consideration the influence factors of threat level of air targets and operational capabilities of weapon system, an improved method of TOPSIS is presented, which is used in comparing and ordering of air targets, and the targets interception order model is also proposed, the optimal solution and the index weights are got by Lagrange multiplier method. Combined with the typical scenario, analysis of example simulation is done and the results show that the method and the model are feasible.