Applied Mechanics and Materials Vols. 37-38

Abstract: For multi-attribute decision making problems including quantitative and fuzzy criteria, a new method with incomplete information for functional requirements based-on information axiom was proposed. When several alternatives satisfy the FRs, the satisfactory degree of users are taken into account in the process of multi-attribute decision making. When the design range of the criterion is unknown, the acceptable range is defined and considered as the design range. The definition and formulation of information content with incomplete information for multi-attribute decision making was developed. All alternatives can be ranked by the total information content, and a final decision was made for the best alternative. Finally, an example on punching machines’ evaluation and selection was used to illustrate the proposed method.

Abstract: The NC-electrochemical contour evolution machining for globoidal indexing cam was proposed. The principle of electrochemical machining with inter injection cylindrical tool electrode and the composition of the machining system was introduced. The algorithm to determine negative electrode enveloping moving path may generate the NC procedure code used for numerical control machining directly.

Abstract: Failures or defects in a product will influence its quality a lot. Reducing or eliminating failures and defects in product design phase is an economical way. FMEA and BFA are two kinds of methods. By using them, the product quality and reliability can be improved in the design phase. This paper introduced a new kind of failure analysis method which was developed based on FMEA and BFA. This is a network failure model and analysis method. By using this method, the product quality could be improved and failures could be reduced.

Abstract: The preparation of Ni-doping alumina foams as precursors for MMCs (Metal Matrix Composites) fabrication was studied. Alumina foams were successfully adulterated with Ni using organic foam impregnation technique. Uniform Ni particles were distributed in alumina struts after they were sintered in a vacuum furnace. At the crucial infiltration step, an inducer such as elemental Ni melted so that interpenetrating channels were created in the ceramics. In contact with Fe melt, the metal matrix could spontaneously infiltrate in alumina foams struts. The influence of infiltration was subsequently investigated by SEM and EDS. Preliminary results showed that the interface between Ni-doping alumina foams and Fe metal matrix reached a full structural homogeneity and the use of Ni-doping alumina foams enhanced the capability of infiltration when processing continuous three-dimensional interconnected ceramics/metal networks MMCs by pressureless infiltration technique.

Abstract: The dynamic model of the gear transmission system is built in consideration of the time-varying mesh stiffness and the gear errors. Then the time history of the dynamic load of system is calculated. The gearbox structural-acoustic coupling system is built and its noise radiation is calculated by using BEM. The noise spectrum of the gearbox and the panel contribution are obtained. The influence of the gearbox structure improvement, structure damping and different gear style on the noise radiation is analyzed. The study provides useful theoretical guideline to the design of the gearbox.

Abstract: The biggest straightening force is one of the important parameters and has an important influence to straightening effect in the straightening process. In this paper, the numerical experiment of loading counterweight force was carried out by finite element analysis software in the steel tube bending. In bending straightening process of numerical calculation, two kinds of steel tube were selected, the size being Φ720mm, δ120mm and Φ325mm, δ55mm, respectively. The straightening force variation law of bending steel pipe was obtained under the plastic state trends in the straightening process. The best control parameters of steel pipe straightening have been identified for the steel pressure straightening and provide a theoretical basis for parameter determination.

Abstract: Semi-fixed abrasive plate (SFAP) lapping is an effective ultra-precision lapping method. It can efficiently obtain good surface quality in ductile regime machining. Probability density function of abrasive grains cutting depth is the key factor to control removing mode. This paper focused on the relationship between processing load and downward movement of the workpiece, which was important equation in probability density formula of abrasive grains cutting depth. By using loading test on pressure tester and numerical fitting method, the relationship can be expressed by different order polynomial formula, and the fitting curves were very close to experimental data.

Abstract: Improvements in manufacturing technologies require better modeling and simulation of metal cutting processes. A fully thermal-mechanical coupled finite element analysis (FEA) was applied to model and simulate the high speed machining of TiAl6V4. The development of serrated chip formation during high speed machining was simulated. The effects of rake angle on chip morphology, cutting force and the evolution of the maximum temperature at the tool rake were analyzed with the finite element model. The simulation results show that the segmented chip formation results in cutting force fluctuation. Although the segmentation frequency of the chip increases with the increase of the rake angle, the degree of segmentation becomes weaker and the cutting force fluctuation amplitude decreases. The predicted temperature distribution during the cutting process is consistent with the experimental results given in a literature.

Abstract: The gas velocity and particle velocity in and out of the nozzle have great influence on the coating effect in the process of cold spray. An axis-symmetric two-dimensional mathematical model was presented to study the flow field in and out of cold spray nozzle, and the effect of different pressure, temperature, spraying distance and particle diameter on gas axial velocity and particle velocity were researched. The simulation results showed that the gas axial velocity and particle velocity increased when the gas pressure and temperature were increased, spray distance had little effect on the flow field in the nozzle, and small diameter particle was more easily accelerated.

Abstract: Based on control equations in fluid dynamics, the main thought of oil mist process for cold heading machine is proposed according to the idea of green manufacturing. The computation fluid dynamics (CFD) software is applied to simulate the multi-phase oil mist flow in control box. The simulation results give some figures including distribution and stream line path of multi-phase flow of oil mist in the control box. The results show that the inlet position of oil mist effects on its process and three types of control box are compared, from which the best type is obtained.