Abstract: Based on the rolling restoration ，the fiber-base body mechanics model is established using casing pipe as hollow fiber, cement loop and mother earth as complex base body during the repairing of destroyed casing well. The calculation formula of stress and displacement are deduced in fiber-base body according to the solid mechanics and discussed the effect of some physics quantity to displacement such as friction coefficient by way of calculation, and have deduced the calculation formula of the cement-loop damage length according to the principle of energy balance. Thus discussing the effect of the friction coefficient and degumming power to the damage of cement loop. The practical circumstances of scene indicate that it is reasonable to using this model to research the cement mantle damage mechanism.
Abstract: The paper studies on the gear reliability design method using probability finite element method based on response surface and it indicates that the reliability sensibility calculation method of function in response surface can be used when limit state function is unknown. The limit state function established on response function is quadratic polynomial with simple form and it makes the calculation of variance and deviation very convenient, which realizes the simple and easy calculation of reliability sensitivity and largely increases calculation velocity and precision. The method can be applied for general purpose with certain standard, which is easy for programming and accomplishing gear reliability design in a rapid and precise way.
Abstract: The traditional optimization method for cold extrusion forming needs to perform finite element analysis repeatedly and therefore has to consume significant computational resource. This paper describes a collaborative optimization method for the cold extrusion die and process parameters of wheel hub bearing rings, combined using finite element analysis, orthogonal experiment, neural network and genetic algorithm. Orthogonal experiment is used to design experimental schemes. Neural network is used to establish mapping relationship between die and process parameters and maximum extrusion force. Genetic algorithm is used to optimize cold extrusion die and process parameters. Via this approach the finite element analysis is relatively independent of optimization process, which just provides training samples of neural network and evaluates the optimized results obtained by genetic algorithm. It overcomes the deficiency of large computational resource consumption of traditional optimization method and provides a fast and effective approach for die and process optimization of cold extrusion forming.
Abstract: The junction line entering is the common flaw that has often arisen in the resistance welding, especially within the resistance seam welding for the high-temperature alloys. It decreases the effective nugget diameter and reduces the tensile-shear strength of welding joint. Stress concentration can be easily created in the junction line entering under moving loading, which induces crack formation and thus seriously affects the welding quality. Owing to the plenty of factors effect on the junction line entering as well as big difficulties for experiment and the high failure rates，junction line entering has the great significance for the stability of welding quality to study its forming and protective measure. The junction line entering for the high-temperature alloy GH163 was studied through the seam welding as follows: surface conditions, welding variables, and agitation force. Some reasonable solutions for entering were provided.
Abstract: In this paper, material properties, geometry parameters and applied loads are assumed to be stochastic, sensitivity computation of structural vibration is presented. The vibration equation of a system is transformed to a static problem by using the Newmark method. In order to develop computational efficiency and allow for efficient storage, the Preconditioned Conjugate Gradient method (PCG) is also employed. The PCG is an effective method for solving a large system of linear equations and belongs to methods of iteration with rapid convergence and high precision. An example is given respectively and calculated results are compared to validate the proposed methods.
Abstract: In order to better understand heat transfer and fluid flow pattern in the weld pool of laser-metal inert gas (MIG) hybrid welding aluminum-alloy process, weld formation mechanism and weld pool dynamic behavior were analyzed by a three-dimensional mathematical model for moving laser- MIG hybrid welding. The temperature and velocity distribution of weld longitudinal section for laser-MIG moving hybrid welding at different moment were discussed to explain flow dynamic behavior in the weld pool. In addition, weld formation mechanism was illustrated by a transverse section heat history evolvement. Moreover, the effects of laser welding parameter and MIG welding parameter on important weld geometry characteristic were quantitatively studied using the mathematical model, and the simulated weld bead geometry parameters were in good agreement with experimental measurements.
Abstract: This paper is concerned with an analysis of the dynamic characteristics of the high performance launcher—rarefaction wave gun(RAVEN) by numerical simulation. Based on its launch mechanism and launch structure, a rigid-flexible coupling dynamic model which considered the coupling effect between the flexible virbation of the launch barrel and the motion behaviors of the other parts of the RAVEN is established via a subsystems method. The actual motion of the projectile and inertial breech during the lauching are described by the interior ballistic equations of the RAVEN. The dynamic characterisitcs of RAVEN is illustrated by the numerical simulation about a small caliber launcher, and the interaction between launch barrel and the other parts is also studied.
Abstract: Performance of gearbox drive system has a great impact on the working life of the whole drive mechanism, especially in wind power generation systems. Using the power split differencial drive system, the objective function of speed up Gearbox optimal design is built adopting the nonlinear constrant minimum function Fmincon from Matlab, the constraints are settled and the relevant parameters of the gearbox with the minimum volume while satisfying the transmission ratio are finally obtained. Then the optimised results is verified with single factor method. The results show that the overall volume of the gearbox is reduced by 9.13% after optimization.