Advanced Materials Research Vol. 744

Abstract: Self-Pierce Riveting (SPR) is a new cold-press rivet technique for hard-to-weld materials joining in the field of automobile lightweight design and manufacture. The interlock slid under mechanical loading was the main induction factor to the failure of SPR joints. In this paper, the property of the interlock slid in SPR joints was studied by using digital image analysis technology and mechanical experiments. A special double-rivets specimen was designed, and simple tensile test was carried out. Several digital microscopes pointing to the region of the mechanical interlock were set up to observe and record synchronously the sequential images of the deformation of SPR during the tensile test. The process of image gray matching for the calculation of the interlock slid was described. Results showed that this method can be used to detect automatically the sliding in SPR joints and analyze the sliding qualitatively and quantitatively. And it can provide a new path for the mechanical property evaluation for this type joints.

Abstract: In this paper, we proposed a new ellipse fitting method converting the ellipse fitting into a circle fitting based on projection transformation. Numerical experiments demonstrate that our approach have good stability and strong robustness against noise in addition to excellent precision and accuracy. In our further research, we successfully extend our algorithm to the construction of the elliptic arc-shaped leading edge by using a tangential contact constraint. Keywords: Ellipse fitting; Projection; PSO; Leading edge

Abstract: In order to development the laser shock processing equipment, the technical features and process demand are analysis. The design requirements about laser shock processing equipment are discussed in detail by the methods of use case analysis and sequence diagram. Functional framework and technology architecture are put forward for the development of laser shock processing equipment. Finally, the equipment structure concept is given which is described for the future equipment design.

Abstract: In order to control the side fall of coal face in great mining height fully mechanized face,this paper proposes a way of controling side fall by ensuring supports setting force,accelerating development,supporting timely of the fully mechnized face and making good use of supports sprag units on the basis of side fall influence study and side fall principle analysis. This paper not only analyses factors influencing stability and explains kinds of sprag units phenomenon of coal face in working face but also conducts quantitative analysis on the influence and provides theoretical basis for measures in order to prevent coal side fall in working face.Meantime,those measures this paper provides are all effectively in controlling coal side fall in great mining height fully mechanized.

Abstract: Research on combustion characteristics of diesel, natural gas dual fuel engine, and to analyze the influence of pilot diesel fuel supply system parameters on the combustion characteristics of dual fuel engine. Based on the experiment, firstly comparing the combustion characteristics of diesel engine with diesel, natural gas dual fuel engine, and compared the effect of load on the combustion characteristics of dual fuel engines, and specifically elaborated the load, speed, rate of substitution, effects of ignition oil quantity, inlet concentration of the mixed gas, the fuel supply advance angle and other factors on combustion changes of dual fuel heat release rate, pressure, discharge characteristics.Analysis of the natural gas / diesel dual fuel engine is currently studying the existing problems of key technologies and development prospects.

Abstract: Uniform constant amplitude rotating current vector subdivision and SVPWM technology are applied to micro-stepping driving system of three-phase hybrid stepping motor. Decompose the stator current vector of the stepping motor into the torque current and the magnetizing current, and then control the currents of decomposition, which makes the amplitude of the resultant stator current vector remain the same. Simulation results show that the designed micro-stepping driving system realizes equal stepper angle, constant torque, and arbitrary variable micro-stepping driving. The use of micro-stepping driving technology improves the stepping motors control accuracy and stability, which promotes the application range of stepping motor and has good practical value.

Abstract: Vehicle radiator is the important heat-exchange equipment to improve the power, economy and reliability of the engine and transmission device, the selection and design of radiator is limited by the vehicle cabin space. In order to meet the cooling requirements, radiator core shape design is optimized. During the radiator core shape optimal design, there is a manual repetitive operation problem when Fluent pre-processing software Gambit establishes 3D mesh model according to the different testing points, Fluent secondary development using VC++6.0 programming language develops the radiator core shape parametric modeling software and improves development efficiency.

Abstract: Non-contacting circumferential segmented hydrodynamic carbon seals have been used in aviation engines to seal lubrication oil from air flow path in bearing locations. Its tight clearance and long life from non-contacting operation are attractive to large gas turbine and steam turbine where efficiency is critical. In this paper, development of segmented carbon seals for large turbomachine is presented. The seal is targeting locations where temperature is over 500C (930F) and rotor diameter is over 0.38 meter (15 inches). Comparing to current circumferential segmented carbon seal technology, the new seal is capable of running 260C (480F) hotter and it is 3 times larger.Three sets of test seals were made with newly developed manufacture process. The test seals are 12 inches in diameter, made of three different carbon grades that were down-selected from a dozen candidates having potential of enduring high temperature of air and superheated steam. A test rig was set up to test one pair of seals at a time. One of the seals is facing high-temperature steam, while the other one is exposed to hot air.

Abstract: Silica films prepared by the base catalyzed sol–gel process show poor mechanical property. In this study, silica anti-reflective films with good mechanical property have been prepared by the catalyzed sol–gel process with dimethyl formamide added as drying control chemical additives. The silica sol was first dip deposited onto substrate to form films on both sides of the substrate and then subjected to thermal treatment. After thermal treatment, the film was achieved due to the formation of porous structure in the resultant film as a result of decomposing tetraethylorthosilicate and dimethyl formamide. Nano-indenter measurement shows that the Young’s modulus and hardness of base catalyzed films are 10-20GPa and 0.25-0.55GPa, respectively. But the films added with dimethyl formamide are much better than those films derived from base-catalyzed silica sols, the Young’s modulus and hardness are 32-39GPa and 1.22-1.47GPa, respectively. The good mechanical properties make such films potential in both military and civil applications.

Abstract: To introduce feature and microstructure of edge crack of rolled coil, character and distribution of transverse corner crack of continuous cast slab (hereafter referred to as transverse corner crack), trace out rolling process of defective continuous cast slab, transverse corner crack of slab causes edge crack of rolled coil, the corner inclusions of slab and rolling process are also significant factors. To give some suggestions to resolve two dimensional heat transfer and high cooling intensity about control of transverse corner cracks. Inclusions cause stress concentration to lead to edge cracks of coils. Edge cracks of coils are related to transverse corner cracks of slabs, but not an exact one-for-one relation. Tiny transverse corner cracks may be removed by scarfing or furnace. Uneven or low temperature of the edge of rolled piece cause uneven extension of edge metal to form “fold”, namely “edge filament”. By research and practice, the quality of slab has been substantially improved in Shougang Qiangang.