Applied Mechanics and Materials Vols. 26-28

Abstract: During piercing rolling simulation, extreme mesh deformation cannot be solved by the finite element method (FEM). Re-meshing is necessary to prevent the effect of severe mesh distortion. However, the element-free method can solve this problem because the continuous body is discretized with a set of nodes, not meshes. In this paper, three-dimension rigid-plastic element-free Galerkin Method (EFG) is introduced to analyze the piercing rolling process. The approximation functions are calculated considering a moving least squares (MLS) approach. The Newton-Raphson method is used for the solution of the nonlinear system of equations. The equivalent stress, the equivalent plastic strain and the equivalent plastic strain rate obtained by EFG and rigid-plastic FEM are analyzed and compared. The simulation results of the EFG method are in agreement with those obtained by using the rigid-plastic FEM and the effectiveness of the model is verified.

Abstract: The qualified rate of flux test is decided mainly by the assembly parameters, but for some reasons, the qualified rate especially the one-turn qualified rate had been on a low level for a long time. By applying 6σ methodology, this paper analyzed the influence factors about the flux test and found out the main influence factors firstly; then on base of these analysis results, this paper proposed some improvement measures; finally, this paper validated the effects of these improvement measures by carrying out some tests. The improvement measures proposed in this paper had improved the assembly quality of scavenging pump obviously.

Abstract: The surface morphology and hardness of electroless Ni–P alloy plating on 6061 aluminum alloys substrate in an alkaline plating bath with sodium hypophosphite as reducing agent were investigated. The effects of bath pH on the plating rate, compositions and surface morphology of theelectroless Ni-P deposits were studied. The results showed the deposition rate of the electroless Ni–P deposits increased with the rise of the bath pH, while the P content decreased. Scanning electron microcopy (SEM) of the deposits showed nodular structure for the deposits. Hardness data of the Ni-P coatings indicated that electroless Ni–P plating could obviously improve the hardness of 6061aluminum alloy.

Abstract: In this article, computational fluid dynamics(CFD) method is used to predict the pressure drop of a wire mesh mist eliminator. A simplification method is used during the simulation process to solve the difficulty of model building during the simulation of the mist pad. A two-dimensional model is employed to acquire the resistance of mesh pad with different layer spacing. The flow field is calculated using 2D Reynolds-averaged Navier-Stokes equations. turbulence model is used to simulate the Reynold stress. And pressure drop of wire mesh mist eliminator is expressed as a function of broad ranges of inlet velocity. After CFD simulation, model experiment study is carried on using a small scale wind-tunnel. The pressure drop is gained to testify the numerical simulation result.

Abstract: The original structure stress state of No. zero frame of TB200 aircraft is analyzed by finite element method. The stress and the reasons of the crack on the frame are determined. The numerical analysis results fit well with the actual damage of the frame, and the finite element analysis model is verified to be reliable. The stress state of the damaged frame structure is analyzed, which shows that the undamaged frame structure must be reinforced. The reinforce plan for the undamaged frame structure is given. The reinforced frame structure is analyzed by finite element method. The stress state and the residual strength of the reinforced frame structure are given. It is showed that the reinforce plan causes an obvious descent of the frame stress. The load is mainly distributed on the reinforcement of the No. zero frame. The residual static strength of the reinforced structure is higher than the original structure. The possible secondary damage position and mode of the reinforced structure are predicted.

Abstract: The key to obtain an effective knowledge base to improve decision quality and enhance organizational core competency is integrating the knowledge from different subjects and sources. We put forward a knowledge integration strategy based on culture algorithm framework. It encodes the knowledge uniformly and evolutes among the two phases of population space and belief space. Through the communication protocol established among the two spaces, an effective and concise knowledge base is obtained. The experiment shows that comparing with traditional genetic algorithm the model can classify the knowledge more precisely, reduce redundant knowledge and remove contradictory knowledge.

Abstract: Manufacturing companies today are looking for the new manufacturing methods.These companies are designing elaborate manufacturing systems in an attempt to meet market trend as well as diverse customer requirements.Recently these manufacturing systems have most often taken the form of Continuous Flow Manufacturing systems, which is represented by one long transfer line containing all relevant operations,or workstations,required to produce a given product.A transfer line of this type is quite susceptible to individual workstation performance,because a breakdown at any one of the workstation would cause the entire line to stop and production to cease. Due to the inherent advantages of Cellular Manufacturing to meet requirements customer, increase productivity, reduce costs,the Cellular Manufacturing can improve the effectiveness of most production line. This paper discusses the development and implementation of a combined production line that takes some its advantages from Continuous Flow Manufacturing and Cellular Manufacturing.

Abstract: Stretch forming process of aircraft skin over reconfigurable compliant tooling is a new technology in skin manufacturing. During this process, the coefficient of friction is important for modeling accurately the process of stretch forming. The objective of this research is to measure the coefficient of friction for aluminum alloy in contact with polyurethane rubber in reciprocal sliding. An orthogonal experimental design was used to reveal the impact of four factors on the coefficient of friction, including lubrication, normal load, aluminum alloy material and sliding velocity. It is shown that lubrication is a major factor, sliding velocity is a minor factor. The influence of normal pressure is less than sliding velocity and the influence of aluminum alloy material is not very obvious. Finally, based on the experiment results, the selections of lubricant and stretching velocity are discussed in order to improve the process of stretch forming.

Abstract: Support vector machine (SVM) is based on the principle of structural risk minimization, which makes SVM has better generalization ability than other traditional learning machines that are based on the learning principle of empirical risk minimization.Research on the application of Support vector regression （SVR） model in spectrophotometry was done to determine the content of benzoic acid and salicylic acid simultaneously. The predicted result was found highly correlated with the time when the data was collected to build the model. The closer of the dates between collecting data for modeling and for predicting, the better the predicted results. SVR model with significantly improved robustness was resulted by using all the collected data over time, which, when applied to the determination of benzoic acid and salicylic acid simultaneously, led to satisfactory result, with recoveries being 97%-102%.

Abstract: Gun pipe linearity check and measure belongs to difficult deep-hole space check and measure. After the deviation data is obtained using designed linearity check and measure instrument for gun pipe, it need carry out analysis and operation to get the error. The essence of using minimum envelope region method to resolve and evaluate gun pipe linearity error is one optimizing problem about envelopment column surface, wherefore, it built error solution model of space linearity based on genetic algorithm, and it developed one solution and analysis software system using VB program. Application shows that the algorithm can be used to resolve linearity error quickly and conveniently, and the precision is good.