Advanced Materials Research Vols. 230-232

Abstract: 0-1 knapsack problem is a typical combinatorial optimization question in the design and analysis of algorithms. The mathematical description of the knapsack problem is given in theory. The 0-1 knapsack problem is solved by ant colony optimistic algorithm that is improved by introducing genetic operators. To solve the 0-1 knapsack problem with the improved ant colony algorithm, experimental results of numerical simulations, compared with greedy algorithm and dynamic programming algorithm, have shown obvious advantages in efficiency and accuracy on the knapsack problem.

Abstract: This paper proposes a genetic algorithm to generate and optimize assembly sequences for compliant assemblies. An assembly modeling is presented to describe the geometry of the assembly, which includes three sets of parts, relationships and joints among the parts. Based on the assembly modeling, an assembly sequence is denoted as an individual, which is assigned an evaluation function that consists of the fitness and constraint functions. The fitness function is used to evaluate feasible sequences; in addition, the constraint function is employed to evolve unfeasible sequences. The genetic algorithm starts with a randomly initial population of chromosomes, evolves new populations by using reproduction, crossover and mutation operations, and terminates until acceptable sequences output. Finally an auto-body side assembly is used to illustrate the algorithm of assembly sequence generation and optimization.

Abstract: In order to obtain a robust dissimilar joint between titanium and aluminum alloy, a method of resistance spot welding with a cover plate were used to weld two kinds of material. The interfacial microstructure was observed using transmission electron microscopy. The effects of welding parameters on the mechanical properties of the joint were investigated. An approximately 160 nm thick layer of Al solid solution supersaturated with Ti was observed at the welding interface, in which contain the precipitates TiAl3. Mechanical property analysis suggests that the reaction layer has no effect on the tensile shear load of the joint.

Abstract: For studying physical properties of Nitrile Butadiene Rubber(NBR) stator of Electrical Submersible-motor-driven Progressive Cavity Pumping (ESPCP) with oil erosion, two different formulations of NBR soaked in crude oil at 90 °C for 168h. Variation rule with time of rubber quality, hardness, volume, tensile strength and elongation rate are got. The results show that erosion in the same temperature, rubber quality increase rapidly in the first 24h, increase slowly down in 24~168h. Rubber hardness does not change significantly soaked within 168h. Rubber volume change obviously in the first 72h and change slowly in 72~168h. In the first 96h, the rubber's tensile strength and elongation rate change quickly, slowly changes in 96~168h. The study has a certain reference of design of ESPCP stator under certain operating conditions.

Abstract: Rare earth doped ZnO particles were synthesized by low temperature hydrothermal method. They showed fine pin-shaped growing along the C axial direction with the diameter about 9-48 nm. The structures of zinc oxide and La doped ZnO were characterized through X-ray powder diffraction (XRD), transmission electron microscope (TEM), Uv-vis diffuse spectrum (UV – vis DRS). Our results indicated that the doping of La results in the crystal cell of ZnO inflating, the band gap shift up to the ultraviolet region with the increase of La doping concentration.

Abstract: A simple steel wire absorber vibration isolation box designation method was proposed through the analysis of vehicular vibration environment and shock absorbs requirements. A steel wire absorber vibration isolation box was designed through the method. Test shows that the vibration isolation box was able to absorb the vibration from the vehicle and protects the equipments in the box.

Abstract: In order to study the influence upper equipment load spectrum from upper spring mass, six freedom vibration signals on the vehicle was measured in a Chinese PG. The signals were the acceleration-time histories. Test was made under 3 loads conditions, which represent 3 types of upper spring mass. After filtering, rainflow counting, fatigue damage caused by the load spectrum was got. Result shows there were great difference in distributions between different direction load spectrums; spring upper load made small influences for the character of load spectrum at the same direction. The upper spring mass became larger, the equipment suffers more damage.

Abstract: The aging of modified asphalt includes modifier and asphalt aging. Combining with the changes of macroscopic properties index for modified asphalt before and after aging, aging mechanism of modified asphalt was studied by gel permeation chromatography(GPC) and grey relevant methods. And the results indicated that changes in content, molecular weight and dispersion degree of asphalt before and after aging are the most significant factors influencing macroscopic properties of modified asphalt. Asphalt content is the most significant factor influencing penetration, toughness and tenacity, ductility(5 °C) and quality; Weight average molecular weight of asphalt is the most significant factor influencing viscosity(135°C); Dispersion degree of asphalt is the most significant factor influencing elastic recovery. Conclusion provides the test basis for the evaluation of anti-aging properties of modified asphalt.

Abstract: For the manufacture of panel parts, incremental sheet metal forming is significant in reality. This study put forward a method of incremental sheet metal forming: High-handed water jet with constant pressure and speed that caused by high pressure system acts on sheet metal and makes it out of shape, following transmutation superposition the requisite parts can be made. Based on this theory, a system of incremental sheet metal forming by using water jet is designed. At the same time, a forming experiment device is developed which is used to test the influence of water jet pressure, sheet metal thick, target distance to forming result. Finally, the optimized technological parameters of forming will be obtained. Within the work range, the higher pressure of water jet is, the more obvious forming result will be, and a great target distance will make forming result worse, besides sheet metal thick can make a difference of it. If sheet metal thick is invariable, there is interaction among pressure, target distance and feed velocity, so they influence forming result together.

Abstract: In the paper, the injection process of mold sleeve is simulated with Moldflow software, and the filling time, cavitation, weld, and causes warping are analyzed. The warping effects on the workpiece surface quality. Moldflow software can optimize gating system and shorten the fill time, improve the quality of plastic surface, reduce the number of repair mode, and shorten the product development cycle.