Ying Xue Yao

Cutting Parameters Optimization by Using Particle Swarm Optimization (PSO)

Cutting parameters play an essential role in the economics of machining. In this paper, particle swarm optimization (PSO), a novel optimization algorithm for cutting parameters optimization (CPO), was discussed comprehensively. First, the fundamental principle of PSO was introduced; then, the algorithm for PSO application in cutting parameters optimization was developed; thirdly, cutting experiments without and with optimized cutting parameters were conducted to demonstrate the effectiveness of optimization, respectively. The results show that the machining process was improved obviously.

Development of a New Virtual Environment System for Assembly

In order to make the operator freely walk in virtual environment (VE), a new prototype of VE system for assembly is presented in this paper. In this system, a special machine is designed and it enables the operator to walk inside the VE in any directions over a long distance without actually leaving the physical device. Images produced by the computer are projected upon the surface of a large spherical cap screen surrounding the operator by means of a group of high power projectors. Signals provided by the position sensors attached to the operator are used by the computer to update the projected images, which provides the operator the illusion of walking freely through the virtual scenes. This VE system can acquire wide field of view and form panorama surrounding the operator, which may enhance the realistic sense of simulation.

Static Performance Analysis of Orifice Compensated Externally Pressurized Gas Spherical Bearing Based on FEM

In order to optimize static performance of a new orifices compensated externally pressurized gas spherical bearing, the paper presents a theoretical study using finite element method (FEM). Galerkin weighted residual method is applied to reduce the order of derivatives of the transformed Reynolds equation. On the basis of theoretical analysis, the influence of supplying pressure and geometrical parameters to radial load carrying capacity and stiffness was analyzed. As a result, the reasonable range of the bearing’s parameters was proposed.

Cutting Parameters Optimization for Constant Cutting Force in Milling

Due to cutting parameters playing an important role in machining economics and machining qualities, much attention has been paid to select optimum cutting parameters. In this paper, cutting parameters optimization for constant cutting force was discussed based-on virtual machining comprehensively. Particle swarm optimization (PSO) was used to seek for the optimal spindle speed and feed rate. The framework of virtual machining based cutting parameters optimization was established. Then two controlled experiments were conducted to demonstrate the effectiveness of cutting parameters optimization both with physical cutting and computer simulation. The results of experiments show that machining process with constant cutting force can be achieved via cutting parameters optimization based on virtual machining.

Study of Local Material Removal Model of Bonnet Tool Polishing

Bonnet tool polishing is a novel aspherical polishing method. This paper describes a method to obtain the local removal rate for the polishing process using bulbous flexible membrane covered with a polishing pad and pressurized by an internal fluid. According to the principle of bonnet polishing and Preston equation, the local removal rate model was established. It is confirmed by the experiments that the local removal depth has a linear relation with the dwell time. Preston coefficient can be calculated from the experimental data. Finally the expression of the local removal rate in bonnet tool polishing is acquired semi-empirically.

Virtual Assembly System for Large-Scale Complex Products

Due to complex process and high difficult operation for large-scale products assembly, the application of virtual assembly (VA) has an important significance and also an actual value. In this paper the key techniques of VA for large-scale complex products are proposed, and their assembly characteristics (such as their organization form, human participation, process planning and optimization and so on) are analyzed. First, a new virtual environment (VE) system considering human activities is set up. Second, an integration approach is realized to transform data from CAD to VA system, and a hybrid method on the basis of virtual reality (VR) and intelligent algorithm is applied to optimize and evaluate assembly process planning. Moreover, assembly documents generation and Web training for assembly workers are implemented. Finally, an application case of the VA system for a complex product is given, and further work is pointed out.

Static and Dynamic Analysis of Carbon Nanotube Cantilever Based on Molecular Dynamics Simulation

Static and dynamic characteristic of carbon nanotube is analyzed by molecular dynamic simulation. Static analysis show that maximum deflection of carbon nanotube appears at 0.033nm distance from free end of cantilever. When the value of driving voltage is less, the flexibility is more important, then the stiffness increase with the voltage increasing, and the collapse structure or hole appear on carbon nanobute. Under low pressure condition, deflection difference on equi-increase of pressure between no damping and damping simulation is larger than that on high pressure. The results of forced vibration indicate that system response consist of transient and steady-state response. With steps of molecular dynamic simulation increasing, transient response disappears gradually, so system response includes only steady-state response, which is simple harmonic vibration with the same frequency as excitation force. These results are in accord with the classical vibration theory. Moreover they will provide theoretic foundation for designing of nanostructure device.

A Survey of Virtual Assembly Technology

Due to the worldwide competition of manufacturing industry and the development of virtual reality (VR) technology, virtual assembly (VA) has attracted many researchers to reduce development cost and improve product quality. As a typical application of VR in engineering, VA has become increasingly important for modern industry. In this paper, a survey of research progress about VA is analyzed. The conception and architecture of VA are introduced at first, the classification is also presented, then the main research contents and key techniques are discussed, finally the limitations and future works are pointed out.

Study on Wear Mode of Silicon Nitride Balls in Lapping Process

To understand the mechanism involved in the lapping process of the silicon nitride balls, the wear mode is investigated in this paper. The abrasion tests were performed on a ball-plate wear test apparatus with different loads (0~2N/ball) and slurry concentrations (5%wt~30%wt W20 B4C3). The abraded surface is observed by optical telescope. A wear-mode map, which defines the regimes for two-body abrasion or three-body abrasion dominating in the micro-scale abrasion test, is plotted with two axes: load and concentration of abrasive. An empirical formula for the wear mode transition is adopted to calculate the transition point S*, which can then used to predict the wear mode in lapping process of silicon nitride ball.

Analysis of the Static Performance of Externally Pressurized Gas Journal-Thrust Bearing with Slot Restrictors

The externally pressurized gas journal-thrust bearing with slot restrictors is investigated by the finite element technique. A consistent transform principle is proposed in this paper to simplify the analysis of Reynolds equation for journal and thrust bearing. The second-order partial differential equation, Reynolds equation, is reduced by one-order with weighted residual method in the discretization procedure, which releases the requirement of continuity degree of the interpolation function while finite element method is adopted. The static characteristics of externally journal-thrust gas bearing are analyzed. Factors that influence the radial and axial bearing capacity are discussed. The interactional rules that exist between the journal bearing part and thrust bearing part are discovered. Predicted characteristics are in good agreement with experimental results.