Applied Mechanics and Materials Vols. 34-35

Abstract: The key point for improving efficiency of Electric Hot Machining (EHM) is to keep an optimal heating temperature in cutting process. This paper introduces the principle and system for realizing optimal heating current control, Electric Hot Machining is applied to minipore drill of hard-material, a method of rapid determining the optimal heating current under various cutting conditions in electric hot drilling is proposed based on the conservation law of optimum cutting temperature. For a certain combination of tool and workpiece, the heating current in different cutting conditions can be obtained by changing heating current and measuring the cutting temperature in electric hot drilling.

Abstract: Because of the extensive application of autotransformer in 500 kV power grid, the value of single-phase short-circuit current is generally greater than that of three-phase short-circuit current, or even greater than the maximum rated through current of the breaker. In order to reduce single-phase short-circuit current and avoid implement of bus split, this paper proposes to install small reactors on neutral points of 500 kV autotransformers. By analyzing and calculating the effect on short-circuit current limitation, the most suitable impedance value of small reactor is proposed. In addition，the overvoltage of the neutral point and insulation coordination are particularly discussed.

Abstract: This article primarily analyzes the shortcoming in the current formula of plastic and rubber mold shaped dimensions in practical， and fully considered the influence of plastic and rubber contracting fluctuation ratio on the accuracy of the plastic and rubber dimensions. As the introduction of δX sources from mold designers’ estimating error on plastic and rubber contracting ratio or the uncertainty of contracting ratio fluctuation, know that the actual contracting ratio of plastic and rubber fluctuates around the average plastic and rubber contracting ratio. Therefore, the remained measure of repairing mold is the function of plastic and rubber products dimension error δS’ and δS, caused by plastic and rubber contracting ratio estimating error and contracting ratio fluctuation respectively. Based on the probability theory, a comparatively scientific method in calculating the remained measure of repairing mold is proposed. This method exceeds all other Calculating Methods increase design success rate use in Green Product Design.

Abstract: As a large agricultural country, rice straw is a kind of inexhaustible and renewable resources in China. Since the rice straw is viscoelastic biological material with low density, it is not conducive to the transport and storage, and it affects the deep processing or secondary development and utilization. Due to the high compression ratio, on the other hand, straw densification briquetteing fuel (SDBF) is great convenience to transport and storage. Simultaneously, it improves the combustion properties of biomass fuels, and increases the efficiency in the use of biomass resources. It has an expansively developing prospects. Accordingly, how to effectively convert the loose rice straw into SDBF is gaining more and more attentions now. In this article, by researching the characteristics of the compressed rice straw fiber, biomass formation mechanism and its influence on shaping factors, the better conditions in processing of rice straw compression molding are concluded. Based on biomass compression molding technology, a kind of flat compression granulating machine was subsequently designed. And then we have designed compressed granulation molding trials on straw with different particle size and different pressures. Experimental results show that the granulation machinery can effectively reduce energy consumption, abrasion of equipment, and raise the productivity.

Abstract: The generalized inductive logic causal model that can synthetically process fuzzy indeterminacy and random indeterminacy was proposed in this paper. On this basis, the new logic indeterminacy causal inductive automatic reasoning mechanism based on fuzzy state description was put forward. At the end of this paper its application on the development of intelligent controller was discussed.

Abstract: In hot stamping process, the die suffers complex thermal mechanical loads. In this paper, the process model and the materials model were set up. And with the example of U-channel forming, a coupled thermal-mechanical analysis is performed with ABAQUS. According to the simulation result, the stress and strain fields of the die show a great uneven distribution in place and time. And the explanation for the non-uniform was given out in this paper. Finally, the fatigue life of the die was evaluated, and the suggestions were proved for optimizing the fatigue lifetime of hot stamping die.

Abstract: Structure vibration test plays an important role in dynamic design, but in most cases the experimental data we get is always limited and insufficient for succeeding upgrade and optimization. The response prediction technique presented in this paper is the corresponding technique to deduce the full field response from the limited data obtained by simple vibration test instead of conducting the full-size test. SEREP (System Equivalent Reduction-Expansion Process) method was used to conduct the prediction research and the procedure was elaborated in detail theoretically first, then several simulations were carried on to demonstrate the prediction procedure, inspect the accuracy under various loads and investigate the factors which may influence the accuracy including the number of modes used in the prediction, the noise, and the measured points. Results show that this method has excellent accuracy and good adaptability to various loads as long as a sufficient set of orthogonal mode shapes participate in the prediction procedure.

Abstract: Transition curve is very important to bending strength and life of gear. In order to improve the bending strength of gear, the shape of three kinds of transition curve (ordinary fillet cutter tip, single circle arc cutter tip and double circle arc cutter tip) was analyzed respectively, the relationship of double circle arc cutter tip parameters was established, the relation model of sensitive part of gear and stress concentration factor ( J and γ) was determined, the effect of different transition curves of gear on bending strength ( ) was explored. The results of analysis show that the bending strength of gear cut by double circle arc cutter tip increases by 10% comparing with that of gear cut by ordinary fillet cutter tip. It provides theories foundation for the design of high bending strength gear.

Abstract: Catastrophic failure of rock mass is a kind of serious geological hazard which usually happens during deep mining excavation and underground engineering construction. Though many investigations have confirmed that it was strongly relate to dynamic disturbances, the disturbing mechanism is still not well-known. The purpose of this paper is to offer a theoretical method to analyze dynamic disturbances induced catastrophic failure. On the basis of synergetic analysis, we established a generalized Langevin equation to describe the nonlinear evolution process of rock mass by considering stochastic dynamic disturbances. Then we further derived a stochastic potential function to research the inductive effect of dynamic disturbances and critical property of catastrophic failure. Results indicate that the influence of dynamic disturbances on the stability of rock mass depends on both the static state of rock mass and the external disturbance intensity. The catastrophic failure threshold is the function of disturbance intensity and control parameters of rock mass.

Abstract: The microstructure and mechanical properties of Mg-6.0%Zn-0.5%Zr (ZK60) and ZK60-2.0%Nd-1.0%Y alloys after extrusion, rolling and then T5 and T6 heat-treatment were investigated. The hardness and tensile strength at T5 and T6 condition were tested. The results show that the mechanical properties of ZK60--2.0%Nd-1.0%Y alloy are superior to that of ZK60 alloy. The hardness of the investigated alloy at T5 condition is higher than at T6. The strengthening of ZK60-2.0%Nd-1.0%Y alloy originates from the interaction of phase and dislocations. The precipitation order of ZK60-2.0%Nd-1.0%Y alloy is GP zone . The magnesium alloy contains rare earth elements with good casting performance, great potential for plastic deformation, high strength, excellent mechanical properties and many other advantages. The magnesium alloy oversaturation solid solution's decomposition process conforms to time the common alloy oversaturation solid solution decomposition order rule, often namely before separating out the equilibrium phase presents some transitional stage the structure, like the GP area, the transition are equal, but the different series magnesium alloy presents the different characteristic, therefore uses the heat treatment method also has big difference [1-5]. In this paper, we will analysis mechanical properties of aging process of testing and microstructure of Mg-6.0% Zn-0.5% Zr-2.0% Nd-1.0% Y alloy , do Research about strengthen the effect of melting and from the product of the relationship on different alloy aging process, and analysis contribution of rare earth elements Nd, Y to alloy strengthen.