Applied Mechanics and Materials Vol. 577

Abstract: Welding technology, as one of the process of manufacturing material in the permanent link, are already widely used in various kinds of aerospace ground launch equipment. Modern manufacturing industry is in rapid development phase, the welding automation is inevitable trend of production, which not only can greatly improve the efficiency of welding, but also what more important is to ensure the welding quality, thus to improve the operating environment. Modern welding is developing in the direction of mechanization, automation, intelligence, robot welding has become an important symbol of welding automation technology modernization. This paper focuses on regularity and influence of welding deformation, the welding deformation and deformation control, control and eliminate problems for research.

Abstract: OLED (Organic light-emitting diodes) is a kind of brand-new display technology. The production involves many processes and different equipments. We studied the optimization problem of interval of preventive maintenance in OLED processes. With the help of ExtendSim software, we perform quantitative analysis and adjusted the productive process. Considering the cost of the preventive maintenance and random corrective repair, We optimized the interval of periodic maintenance with the limit of total output and obtained the best profit and lowest maintenance cost.

Abstract: The spring-back phenomenon in automotive panel forming is one of the main quality problems, which may affect the tolerance and final shape of panel products. The stamping and spring-back process simulation for the automotive panel were realized by using the Auto form software, emphasizing on the possibly spring-back quantity forecasted and the die surface was optimized to control spring-back. The reasonability of optimization scheme was proved by comparing the simulation result with the actual part.

Abstract: The mathematical model of convert steelmaking end point prediction model based on RBF(Radical Basis Function) is presented in this paper. According to the end point prediction problem of the converter steelmaking production prediction problem, we establish the forecast model of converter steelmaking process which describes the relationship between variables such as hot metal quality, oxygen blowing, the quality of the cooling agent and additives etc. and the end point molten steel temperature and carbon content. The prediction system is multidimensional and nonlinear. The model between variables and the target is unknown. For this situation, this paper applies RBF neural network to forecast target, establishing the prediction model based on RBF neural network. So as to obtain the variables and the mathematical model between steel endpoint temperature and carbon content.

Abstract: The structural stability of MgCe under high pressures has been investigated by using the first-principles plane-wave pseudopotential density functional theory within the local density approximation (LDA). The obtained results predict that MgCe in the Ba structure is predicted to be the most stable structure corresponding to the ground state, because of lowest total energy. MgCe undergoes a pressure-induced phase transition from the Ba structure to B32 structure at 36 GPa. And no further transition is found up to 120 GPa. In addition, the electronic structures of four structures of MgCe are also calculated and discussed.

Abstract: The discrete element method (DEM) is applied to glass micromachining in this study. By three standard tests the discrete element model is established to match the main mechanical properties of glass. Then, indentating, cutting, micro milling process are simulated. Results show that the vertical damage depth is prevented from reaching the final machined surface in cutting process. Tool rake angle is the most remarkable factor influencing on the chip deformation and cutting force. The final machined surface is determined by the minimum cutting thickness per edge. Different cutting thickness, cutter shape and spindle speed largely effect on the mechanism of glass.

Abstract: During the STIRAP process, the intermediate levels will have notable population which is detrimental if these levels could decay to other levels through spontaneous emission. Here, we propose a novel method which could reduce the intermediate level population during the STIRAP process. A complete population transfer could be achieved in this modified STIRAP even if the intermediate level could decay to other levels.

Abstract: A numerical procedure to compute the mean and covariance matrix of the random response of stochastic structures modeled by FE models is presented. With the help of Gegenbauer polynomial approximation, the calculation of dynamic response of random parameter system is transformed into an equivalent certainty expansion order system's response calculation. Non-stationary, non-white, non-zero means, Gaussian distributed excitation is represented by the well-known Karhunen-Loeve (K-L) expansion. The Precise Integration Method is employed to obtain the K-L decomposition of the non-stationary filtered white noise random excitation. A very accurate result is obtained by a small amount of K-L vectors with the vector characteristic of energy concentration, especially for the small band-width excitation. Correctness of the method is verified by the simulations.

Abstract: This paper aims at the phenomenon of uneven wear of working roll and the work-side wear is much higher than the drive-side of an acid rolling mill tension leveler for dynamics simulation analysis, analyzes the vibration characteristics of working roll in different process parameters and different bias conditions of rolls and vibration test is carried out to test the rolls by Donghua5920 test-collection system, and combined with the field vibration data of bending roll, points that unilateral severe wear of bending roll is mainly the zero problems of tension leveler.

Abstract: Drilling jar is widely used to solve the stuck pipe incidents in the drilling process. Impact force which is being made during the jarring operation is acting on stuck point to achieve unfreezing effect. Conventional hydraulic dynamic load calculation method is not considering the impact of friction force on stress wave spreading in drill string. In actual process, friction and viscous resistance caused by the movement of drill string in drilling fluid, making drill string acceleration process exhibiting damped vibration characteristics. Therefore, with the drill string damping vibration theory, analysis of dynamics of acceleration process can be made, and displacement and velocity equation in longitudinal acceleration process can be deduced. Thus the maximum velocity of drill string before collision has been calculated, and impact force acting on the stuck point has been deduced with the law of conservation of energy and momentum. The model of impact force calculation is more satisfied with actual environment in the wellbore during jarring operation.