Papers by Author: Sheng Guan Qu

Abstract: The quality of the honeycomb radiator structure has a great impact on thermal performance of the LED lamp. In order to make honeycomb radiators structure more uniform and materials fluidity much better; we firstly take use of cold extrusion to form the honeycomb radiator, then it will be machined. In the honeycomb radiator deformation than the larger places where prone to stress concentration, that has a seriously affect on the effect of the radiator forming. Therefore, we optimized the extrusion die, including upper and lower mold prone to stress concentration places create fillet. The results show that an appropriate fillet of the mold can greatly improve the forming uniformity and reduce the force on the die.

Abstract: Two factors must be given considered in low friction cylinder , which are sealing and wear. A lower contact pressure can lead to seal failure. However, a heavier contact press can increase friction force and wear. In the present paper a method have been proposed to obtain the optimal contact pressure between PTFE wear-resistant ring and the steel bushing at first, with analysis of the relationship among the surface roughness, the sealing contact pressure and the leakage. Secondly,the piston groove Diameter has been designed by using the finite element analysis software of ABAQUS to simulate the Mooney-Rivlin model, which is corresponding to this optimal contact pressure. On the premise of meeting the requirement of the specific leakage standard between the cylinder and the wear-resistant ring, the optimal contact pressure and the corresponding piston groove size have been obtained, with different surface roughnesses of the friction pairs.

Abstract: Radiators plays a crucial role in thermal performance of LED Lamp, and the latest development of LED honeycomb radiator forming process has been discussed. Moreover, stress-strain state in the dies and blank flow condition with different die structures have been studied by DEFORM. Accordingly the feasibility of the optimization design also has been demonstrated. The results show that the substance flowing has a serious affect on the force to the die. And with an appropriate die structure, the uniformity of forming can be greatly improved and the force to the die can be reduced.

Abstract: nfluential degree of different surface structures on stable output power of diesel engines under continuing work condition was evaluated, and relatively comprehensive reference optimizing micro-geometric morphology structure on cylinder liner surface was provided, through performing friction and wear experiments of cylinder liner and piston ring with three kinds of different surface structures: honing textured surface, no textured surface, and crater-grooved surface on an Optimal SRV IV oscillating friction and wear tester respectively, and analyzing effects of different surface structures on vibration of friction coefficient with power spectrum density. Results show that crater-grooved surface structure has smaller vibration value of friction coefficient under low loads and fluid lubrication state, while roughness determines vibration of friction coefficient under high loads and boundary lubrication state.

Abstract: Based on combustion pressure, the dynamic model was established by using AVL Excite Piston and Rings. Relative axial position and wear loss of rectangular piston ring in a work circulation were analyzed. Based on the shape of the rectangular ring outer side after abrasion, the piston ring cross sections were designed to barrel and tapered shape. Results indicate that improved gas rings are suffered substantially decreased friction. The friction of the first gas ring is less than 100N, and the second ring is even less than 20N. At the upper dead point in the compression stroke, the oil film thickness reaches the minimum value and the piston rings do not pump oil to the cylinder combustion chamber.

Abstract: In tribological system of internal combustion engine, cylinders and pistons were in high temperature, pressure and load working status. An SRV IV wear tester was used to measure dynamic coefficient of friction by simulating working condition of cylinder liner and piston ring. The worn surface topography was observed through scanning electron microscope and metallography. The results show that loads had little effect on the friction coefficient under oil lubrication. Cylinder with the high-chromium carburizing ring in pairs displayed wear in the form of plastic deformation, while cylinder with the phosphide cast iron ring in pairs displayed adhesive wear. The piston ring was subjected to shear stress and tensile force under dry friction condition and deformed into tapering burr. Lubricants played a bearer role under lubrication condition; therefore, surface borderline of piston ring was relatively flat.

Abstract: To investigate surface stress distribution of rectangle piston ring, method of increment loading based on energy variational principle is used to ascertain contact state and solve elastic contact problems by iteration. Calculation results show that the central section of the first sealing surface is subjected to lower stress while two sides higher stress. The theoretical analysis and experimental results indicate that appearance of stress peak on surface is related to movement direction of piston ring. Relatively critical wear regions of piston ring are consistent with finite element analysis results. Wear width of both sides is 0.2mm more or less. The section of maximal stress appears at position near ring groove of the first sealing area.

Abstract: Spark plasma sintering (SPS) method was used to consolidate ultra-fine and mixed 93W-5.28Ni-1.32Fe-0.4Y2O3 (wt pct) powders, and the effects of sintering parameters on the densification degree and the performance of the as-sintered materials were investigated. Results showed that the SPS densification process could be divided into four stages. Compacts were densified rapidly at the stage III and a proper holding time promoted W diffusing into fcc-type Ni-Fe based solution. Heating rate and sintering time had a great influence on densification. When the powders were heated at a rate of 100°C/min to 1230°C and then held for 5min, the density, hardness and transverse rupture strength of the as-sintered material reached the optimum, being 17.18×103kg/m3, 41.4HRC and 935.1MPa, respectively. Its corresponding fracture morphology was characterized as intergranular rupture of W-W, and accompanied with some transgranular cleavage of tungsten grain.

Abstract: Commerical pure WC powders of 0.2, 0.4, 0.8, 2.0 and 3.0 m in diameter were sintered by spark plasma sintering process at 1300 °C, respectively. By analyzing the XRD patterns of the initial powders and the microstructure of the sintered samples, it is affirmed that the powders with an average size of 0.8 m exhibits the best activity and sintering property. To optimize sintering temperature, the sintering of 0.8 m powders was carried out at 1200-1700 °C. The specimen sintered at 1300 °C has a density of 15.49 g/cm3 and an average grain size of about 0.7 m, and exhibits the most excellent mechanical properties. The corresponding Vickers hardness and transverse rupture strength are 2469 HV and 1656 MPa, respectively.

Abstract: In this paper, frictional behaviors of tool, workpiece and chip in turning particulate reinforced iron-based composites were investigated. Experimental results reveal that in frictional process, the frictional coefficient decreases with the normal force increasing or with the reinforcement content decreasing. In turning process, the variation rule of such parameter is just similar to that of frictional process, but frictional force and average frictional coefficient on rake face are more than that of frictional process. Meanwhile, the frictional mechanism of cutting tool and material is also studied. It indicates that adhesion occurs on tool-chip interface. The intense scratching of reinforcing particulates blocks the formation of adhesion layer and makes the frictional coefficient decrease, on the other hand, it increases the sliding resistance of chip, which makes the frictional coefficient increase. Since the latter is dominant, the tool-chip frictional coefficient increases with the increase in reinforcing particulates.