Advanced Materials Research Vols. 201-203

Abstract: In this paper, numerical simulation was carried out for the tube bundle of a slurry oil steam generator with concentration on the thermal stresses at the tubesheet with or without a welding clad on the tubesheet surface. It is found that as having a larger heat expansion coefficient, thermal expansion of the welding clad is constrained and most areas are in compressive state. But the tensile stresses in the clad are also notable especially at the interface and could break the clad if added by the tensile stresses produced by pressure loadings. Presence of the welding clad causes significant tensile stresses in the base tubesheet. It is possible that the maximum tensile stress comprised by the thermal tensile stress and pressure induced tensile stress will exceed the tensile strength of the material and cause initiation of cracks in the tubesheet.

Abstract: To optimize injection molding process, the gating system, cooling systems and related injection molding process parameters are chosen as the experimental analysis factors, the quality of the injection as the experimental index in this paper. First, design the test program with orthogonal experimental and simulate with Moldflow MPI 6.0. Second, after plastic molding, in order to determine the integrated target, the comprehensive evaluation method of fuzzy mathematic is used to evaluate warpage values, shrinkage and residual stress. Finally, get the optimization scheme and the best match of gating system and cooling systems though the range and variance analysis of integrated target. The experimental results shown this optimization method can achieved the best parameters for practical produce. So, the optimization injection molding method, MPI and experimental design based, has important practical significance.

Abstract: The brake system is very important part of the machine working. The mooring winch brake holds the ship on the harbor. But sometimes it appeared the excessive stress and brake lining would be broken. So it is necessary to change the shape of brake system with improve the durability of brake band. In this research, three models, such as a single brake shoe with a uniform thickness, a dual brake shoe with a uniform thickness, and a dual brake shoe with different thickness, are adopted as analytic model. In order to evaluate the strength of band brake according to the shape of brake shoe, the finite element analysis for three models is carried out by using ANSYS Workbench.

Abstract: In this paper, an integrated approach of CAD/CAM was presented for the spatial cam with oscillating cylindrical rollers. The relationship between the cam profiles and the meshing element’s surface is established by the conjugate surface theory. In the machining process, the cutter location for the rough and the finish machining using cylindrical-end mill is derived. To avoid interference, the principal curvatures and the principal induced normal curvatures between the cam surface and the cutting tool are analyzed. The geometric error was used as a basis for generating appropriate toolpaths. The postprocessor are developed for converting the cutter location file to the five-axis numerical control program. The generated NC program is verified before actual machining through solid cutting simulation. In order to demonstrate the applicability of the presented method, cam profile was cut using a five-axis machine tool with real material.

Abstract: The technology of Pipeline high-pressure intelligent isolation is a new technology which has been developed by Company PSI since the 1990’s, and the core technology, packer’s sealing performance has been blocked from then on. In this paper, we study the Polyurethane columns specimen of different hardness though ANSYS, then fit with the curve from the experiments, in order to get the Polyurethane columns’ Mechanical constants of Model Mooney-Rivlin. Calculate the deformation between two statuses, then according to isolation pressure and anti-convexity of packer we choose the packer of appropriate hardness. Finally, analysis the packer under different pressure, get the working curve of isolation ability, and the outlet can be used in the design of packer.

Abstract: To resolve the problem of the parts deformation because of the milling force, a finite element model (FEM) of end milling process simulation in milling force field was established. On the base of FEM, we simulate the high-speed end milling type structure of aluminum alloy 7075 parts. We successfully predict the end milling force, obtain the effect between the upper and lower material to the milling force, and Mises stress and the tool length beyond the part.The simulation results show that the lower material can increase the milling force to upper, and upper material can decrease milling force to lower layer.The drilling tool length beyond the part is about 0.5 mm .

Abstract: Research on thermal and mechanical distribution of a piston under working condition was performed by using indirect couple method. It is shown that the highest temperature is within the permit and piston ring sticking will not happen. At the same time, the largest stress bellows allowable stress of the material, so the piston can meet the requirement. Also, the result in this article provides reference for piston design and optimization.

Abstract: In the rehabilitation engineering area, the pressure ulcer prevention is an important and healthy problem, especially for people with the spinal cord injured (SCI). This paper aim to develop a computer aided design and computer aided manufacture (CAD/CAM) method to manufacture custom cushions to prevent pressure ulcer. A patient’s buttock was digitized using 3D laser scanner, and the captured buttock data was processed in reverse engineering environment to generate the 3D surface model of the buttock. The 3D surface model of the buttock is imported into Unigraphics software to create the solid model; then, a flat rectangle that represents the cushion was generated under the buttock to create the buttock-cushion system. Based on the load-deformation relation of cushion materials acquired by the test, the depth of cut of the cushion was established and a CAD model of cushion shape was created through a Boolean subtraction. The CAD model of the contour is post-processed into code that the numerically controlled milling machine (CNC milling) can use to machine the cushion.

Abstract: Higher speed and loading capacity of trains nowadays have aroused higher ability of crashworthiness, which could be effectively improved by well-designed energy absorbing structures. The thin-walled components, the most traditional and effective energy absorbing device, have been widely used for design of energy absorbing device. As a result, the thin-walled components are used as an example to examine the process of axial compression of it. A comparison of a dynamic compressing simulation on fold-collapse tube and the experimental result of it is made, which shows the two matches very well. Based on this comparison, a further research and optimization on the thin-walled energy absorbing components is implemented. With the material modal and finite element modal of this component, a research on the simulation of PAM-CRASH, the crashing finite element Software, is implemented on such component with different shapes of cross-section, different thickness and square cross-sections with single-cell and multi-cell. What's more, suggestions on such thin-walled components energy absorbing structure is given based on the analysis of the parameters of the simulation.

Abstract: This paper presents a unified and mixed interpolatory and approximation subdivision scheme for triangular meshes. It can be used to solve the "popping effect" problem when switching between meshes at different levels of resolution. The scheme generates surfaces coincidence with the Loop subdivision scheme in the limit condition having the coefficient k equal 0. When k equal 1, it will be changed into a new interpolatory subdivision scheme. A new set of rules is designed for computing the newly inserted vertices around extraordinary masks. Eigen-structure analysis demonstrates that subdivision surfaces generated using the new schemes are C¹ continuous. The method is a completely simple one without constructing and solving equations. The example of British Museum shell design show the great flexibility advantage of mixed subdivision design method in shell architecture, even in other industry design field.