Advanced Materials Research Vols. 791-793

Abstract: Lateral field excitation (LFE) acoustic wave devices, which employ two electrodes on the same surface of a piezoelectric substrate, have been found attractive in sensing applications. However, up to now, the sensitivities of pure-LFE devices based on LiNbO₃ single crystal is unknown. In this work, the effective LFE exciting electric field direction of (yxl)89° LiNbO₃ is determined. The calculated results showed that when the driving electric field direction is perpendicular to the crystallographic X-axis of the piezoelectric substrate, (yxl)89° LiNbO₃ LFE device works on pure-LFE mode. Based on this, several LiNbO₃ pure-LFE bulk acoustic wave sensors with three different electrodes are designed and fabricated. The results show that the (yxl)89° LiNbO₃ LFE sensor with interdigital electrodes is 11.1 times and 2.2 times more sensitive to changes in liquid conductivity compared to traditional LFE devices with single gap circular electrodes and Archimedes spiral electrodes, respectively. The results are important for investigating high-sensitivity LFE bulk acoustic wave sensors by using LiNbO₃ single crystal.

Abstract: At present, pulley produced in China has been able to meet the demand of domestic and international markets. But there are many problem of the pulley industry in our country, such as too many production enterprises and the low level of export products. And as components of drive system are light weight and raw material price of pulley casting are rising, manufacturing requirements of the pulley are also more and more high. Aiming at the casting defects of pulley that enterprise current product, pulley casting blank model of common material HT250 be made by three-dimension software, numerical simulation of filling and solidification process for pulley sand casting by the casting simulation software Procast, the size and location of the various casting defects were forecasted and analyzed, reflecting the pulley filling and solidification process of the actual situation, due to the thicker pulley rim and less heat dissipation, position of shrinkage is close to the middle of rim [, a method of eliminating defects is proposed to realize sequential solidification, and thus to minimize porosity shrinkage and improve casting performance and reduce casting time and reduce production costs.

Abstract: U shape brass tube bundle on heat exchanger cracked when it was having ammonia leak test. Sample was made from brass tube fragment, polished the surface of the sample, eroded it with solution of 5% iron trichloride (FeCl₃) and 10% hydrochloric acid (HCl), then took photos with Nicon-300 metallographic microscope. The fracture is a kind of stress corrosion cracking, the reason of cracking was analyzed. The technology of test was improved, the method should be paid attention to during brass tube exchanger manufacture was given out too.

Abstract: Due to its good formability characteristics, such as high strength, high initial work hardening rate, as well as continuous yielding, thin-walled DP steel possesses great advantages of weight loss and security, and has been used to replace ordinary steel for automotive parts manufacturing by a lot of automotive industry. But along with the improvement of the performance of the strength, the high strength steels formability is worsened dramatically, and failure and fracture often occurs in its cold stamping process. So, hot stamping technology must be adopted to make the formability available. In the paper, it took the hot stamping process of DP steel engine hood for example and took DP800 as object of research. The forming limit, variation of major strain, minor strain and thickness, as well as the potential equality defects were analyzed by using eta/DYNAFORM software. The research results show that duplex steel plate can meet the performance requirements of car engine dumping plank forming, which offers theory basis for the production of similar parts.

Abstract: Vibration moulding of expendable pattern casting (EPC) was simulated by three dimensional discrete element method, a special EPS tube for test was devised, and the law of vibration form on the motion of sand group was summed up. The results show that vibration form and filling motion of sand group in-tube has consistency in the direction, at the same time gravity and tube direction have a great influence on sand group motion, which leads to particularity of Z tube and Z vibration.

Abstract: Using three-dimensional discrete element method (DEM) to simulate the vibration of the evaporated pattern casting molding process, accordingly summary the influence law of vibration direction effecting on dry sand filling. The results show that the 3DOF vibration filling effect is best, 2DOF takes second place, 1DOF is the worst. In the 2DOF vibration the YZ direction is best, XY direction worst. Meanwhile Y direction vibration works best in 1DOF vibration, second is X direction, and Z direction gets worst.

Abstract: The displacement and the angle of the continuous beam are researched under the complex loads in this paper. Based on the analytical model suggested by the authors, the nested dynamic objective function is determined to form the optimization of beam deformation, and a program analysis of typical examples is presented. It is compared both analytical model and simulation results based on finite element software of ANSYS10.0. The results show that the analytical model suggested by the authors is correct.

Abstract: 1040 °C was studied during the period imposed 137MPa tensile creep nickel-base single crystal superalloys γ/γ the evolution of two-phase approach. ANSYS finite element method is using a single crystal alloy with / without external load when the Von Mises stress in the gand γ two phase distribution. The comprehensive analysis of the formula, the coefficient values usually experience, not very accurate, this article dealing with GA coefficient. This algorithm uses orthogonal crossover to generate initial population and uses elitist-crossover to increase the good patterns of the population and uses hybrid mutation to increase the ability of local and global optimization. It has shown fascinating results when being used in the optimization of multimodal function. The results showed that: In the creep period, the corresponding cubic γ along the von Mises stress and strain energy density of the crystal face to form raft-like organizations.

Abstract: The paper researches on the coating performance prepared by sputtering stainless steel particles to Cu substrate, analyzes the effect of the six magnetron sputtering process parameters on absorption rate, such as Ar pressure, oxygen flow, sputtering vacuum degree, sputtering time, target voltage and target current with the artificial neural network technology, and forecasts the performance of the coating prepared by specific process parameters. The results show that during the process of magnetron sputtering when Ar pressure is within the range of 0.2 ~ 0.5 Pa, the oxygen flow is within the range of 0 ~ 20 sccm, and the target current is within the range of 380~ 430 A, the higher the sputtering vacuum degree and the target voltage, the superior the performance of the coating can be obtained. It is also found that the sputtering time has little effect on the coating performance, in the actual preparation process, on the condition that the performance can be guaranteed, the sputtering time should be as short as possible.

Abstract: The constant matrix and piezoelectric equations of quartz crystal material are introduced in this paper. Vibration characteristics of quartz crystal is analyzed under several important vibration mode and coupled modes are explained. At last, some measures to suppress the QCM vibration coupling is presented.