Applied Mechanics and Materials Vols. 10-12

Abstract: A heuristic approach was presented to automatically partition a triangle meshes into a coarse quadrangular segmentation. The triangle mesh was firstly partitioned into a polygonal segmentation which will further be split into triangular and quadrangular patches. At last, the quadrangular segmentation was obtained by eliminating triangular patches according to their topological relations. The final segmentation consisted of pure-quadrangular patches with appropriate sizes according to the model’s geometric characteristics, and the features of input model were well captured. Experimental results showed that the algorithm was efficient and effective.

Abstract: For a manufacturing enterprise to be competitive in constantly changing market environment, it is necessary to adopt a new model called agile manufacturing by organizing Virtual Enterprise. Aimed at developing a product development process management (PDPM) system for Virtual Enterprise, modeling of product development process is discussed and a union information model is proposed using Object Modeling Technique. Based on the J2EE platform, a framework of PDPM system is built up with a three-tiered architecture, which consists of several Enterprise JavaBeans components to ensure compatibility, distribution, and flexibility of the system. A PDPM system prototype is developed utilizing JAVA and has been validated in a simulated virtual enterprise environment.

Abstract: High performance machining refers to the material removal operation that delivers the maximum achievable part quality, process competitiveness, and ecological compatibility through strategic utilization of cutters, machine tools, operation configuration, and process parameters. It is rapidly emerging as a prerequisite to productivity and profitability of machining operations and associated manufacturing systems. To accomplish high performance machining, a thorough understanding of the underlying mechanics that affect the performance attributes such as tool life, part integrity, air quality, etc., and how it is attributed to tooling conditions, operation configuration, and process parameters, is required. This paper reviews and summarizes a series of analytical methodologies by coupling with studies performed at the Georgia Institute of Technology for the quantitative modeling of fundamental mechanics of machining in the context of thermal, mechanical, tribological, and metallurgical effects and their interactions. In this study, cutting stresses, residual stress and tool life are explicitly described as functions of tool geometries, cutting speed, chip load, cutting fluid properties, interface tribological conditions, and the cutter/workpiece material constants. These analytical models facilitate the prediction of machining performance thereby allowing the optimal planning of machining processes in pursuing maximum performance. An array of experimental cutting data is also presented in comparison to model-based predictions for the validation of all aspects of the machining mechanics analysis.

Abstract: Electrical discharge machining (EDM), as an effective method, can be used to implement the finish machining for turbine blisks. Searching an interference-free path for feeding an electrode through twisted tunnels of a rimed blisk was carried out. Based on the approach coefficient of free surface defined, the electrode kinematic constraints and object function were determined. The two-step path searching is applied for searching the interference-free path. Finally, the path searching algorithm is verified with an example.

Abstract: Reconstituted nanostructured partially stabilized zirconia (PSZ) feedstock powders were laser sintered under a range of laser processing parameters. Scanning electron microscopy (SEM) was applied to analyze the microstructure of the powders and sintered bulk. Microhardness of the samples was also tested by Vickers Microhardness tester. These results demonstrated that the microstructure of the samples exhibits a bimodal distribution which comprises molten and non-molten feedstock particles. It was found that feedstock maintained some of its nanostructure during laser sintering with relatively low laser power; whereas feedstock lost most of its initial characters with high laser power. It was also observed that Microhardness values have respect to the proportion of non-molten feedstock in those samples.

Abstract: The NC machine tool is widely used in today's manufacturing industry. In this paper, a framework of the NC lathing dynamic simulation system is presented and the machining process simulation is developed based on the solid modeling method with ACIS geometric engine and 3D graphic display. The tool swept volume is designed and Boolean difference of the cutter swept volume with the raw stock in the system is calculated. The user or trainee can practice all operations, procedures and skills in complete safety, while maintaining a high degree of realism.

Abstract: Three-dimensional finite element simulations were used to investigate the influences of various hot filaments and other deposition parameters on the temperature field of substrates which affect significantly the growth and quality of diamond films by hot filament chemical vapor deposition (HFCVD) and based on the simulation results, the optimum position for diamond deposition was found. In the experiment, six cemented tungsten carbide inserts were used as substrates and placed on the workbench in the CVD reactor to deposit diamond films. According to the temperature distribution on substrates measured by thermocouple fixed in CVD reactor, the simulations were validated and the optimum arrangement of substrates was established from the simulation results. In addition, the simulation model was altered to optimize the process parameters of HFCVD deposition, and an improved process of depositing diamond films with high quality was obtained in order to achieve the great surface morphology, which laid the foundation of developing a new method to arrange the substrates in the CVD reactor for depositing diamond films.

Abstract: A new method of state recognition of milling tool wear was presented based on time series analysis and fuzzy cluster analysis. After calculating, verifying liberation signal of tool state, and analyzing cutoff property, trailing property, periodicity of the sample autocorrelation function and partial autocorrelation function as well as estimating parameter of model. It can be decided that dynamic data serial is suit AR(p) (autoregression) model. Taking p equal to 12 as a feature vector extraction, based on the fuzzy cluster analysis the similarity relation between the feature vector of the tool working state and the sample feature vector was obtained. Working state of tool wear was determined according to the similarity relation of feature vector. This method was used to recognize initial wear state, normal wear state and acute wear state of milling tool. The result indicates that this method of tool wear recognition based on time series analysis and fuzzy cluster is effective.

Abstract: A new strategy for 5-axis NC machining called Rotate-For-Intersect Machining (RFIM) was presented in this paper. The cutter was settled by two cutter contact points and in order to obtain optimized tool position and orientation, grid point method and bi-section method ware utilized in searching cutter’s rotate angle and tilt angle. Finally the algorithm was implemented on UG platform following further development and the effectiveness of the method was validated.

Abstract: 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.