Advanced Materials Research Vols. 189-193

Abstract: The metal transfer process with different welding parameters in rotating arc narrow gap horizontal welding is successfully observed by the high-speed photography system. The effects of wire rotating frequency on metal transfer process in rotating arc narrow gap horizontal welding are novelly explored. The metal transfer with different wire rotating frequency presents different modes. The results indicate that the droplet transfer has stable process with the rotating frequency of 5-20 Hz. And the weld formation is quite shapely. But with the high rotating frequency of 50 Hz, the metal transfer process is not acceptable and the weld formation is very pool. Metal transfer process is one of the most important factors of effecting the weld formation in rotating arc horizontal welding process besides the molten pool behavior and welding thermal circles.

Abstract: It’s significant to analyze the dynamic reliability of wind turbine in order to assure the safe and stable operation of wind turbine. In this paper, the dynamic reliability of wind turbine is analyzed with the propeller-type generator as example. The stability of blade of wind turbine under wind load is analyzed by calculating the fatigue load on blade. The frequencies of bending free vibration and torsion vibration of tower are summarized. Finally, the type of foundation and its simplified model are instructed and some useful conclusions are given for supplying basic information on dynamic performance of wind turbine.

Abstract: Material flow during friction stir welding is very complex and not fully understood. Most of studies in literature used threaded pins. However, analyzing material flow using smooth pins is of great interest for the validation of a numerical model in which threads are difficult to represent. In this study, FSW experiments were performed using smooth pin based on plasticine analog. Longitudinal, horizontal and transverse sections of welds were observed with the use of plasticine of identical type but different color as material marker to investigate the material flow. A horizontal ‘vortex-like’ action has been occurred. In the agitating-extruding region (inside the pin diameter), a clockwise (identical to the rotating tool) layer appears around the tool, as a result the material both the advancing side and retreating side is mixed. In the deformation region (outside the pin diameter), the material is driven by the clockwise viscous force of the rotating pin, and the effect is reduced with the increase of the distance to the weld center.

Abstract: The paper makes study on the legs connection technology of jack-up drilling platform. It analyzes the high strength and large thickness rack plate’s material characteristics, and gives the welding process for this material and notes during welding. The important technologies are the rack plate’s joint and the chord’s joint. Based on 152.4mm and 127mm thickness steel plate, this paper makes a detailed study on these two important technologies.

Abstract: There are many types of shells in the world of biology such as various egg shells, conch shells, tortoise shells and skulls of human, all of them are one kind of thin shell structure with uniform curvature and lightsome of texture. This structure is not only light but also has a good pressure resistance. The composition, microstructure, and three-point bending properties of the turtle shell are studied in the paper. The results show that the turtle shell is composed of the element of Ca, P, C, Cl and Na etc. There are many pores in the turtle shell, and the cortical outer layer and spongy inner layer with collagen fiber winding. The middle layer with many pores absorbs energy and lower the load when acts on it. Therefore, the shell can protect the soft tissue of turtles. The multi-layer and porous structure will provide basis for design of biomimetic such as lightweight composite damping materials.

Abstract: Punching bonding made for study context and Autoform selected for platform, numerical simulation of stamping was carried under different shapes, different materials, different parameters, and the different simulation results was gained . And deformation, the thickness of the forming limit analysis of simulation results, etc., and thus such important parameters as the thickness of sheet metal, punch diameter, the speed and the size of power punching and etc.,was modified and debuged, the combination of optimized process parameters of sheet metal was achieved in the final. Therefore, AutoForm not only can be used to overcome the difficulties,which there is no standard available, relying on repeated experiments to determine the parameters of the connected so as to achieve green design stamping; but also be made for stamping die design and production of connections to increase the efficiency and the expansion of the stamping connections the scope of the application.

Abstract: This paper deals with the stress distribution in adhesively bonded joints with rubbery adhesives. The 3-D finite element analysis (FEA) software was used to model the joint and predict the stress distribution along the whole joint. The FEA results indicated that there are stress discontinuities existing in the stress distribution within the adhesive layer and adherends at the lower interface and the upper interface of the boded section for most of the stress components. The FEA results also show that the stress field in the whole joint is dominated by the normal stresses components S11, S33 and the shear stress component S13. The features and variations of these critical stresses components are discussed.

Abstract: Spot welding of magnesium alloy was a complex processes of thermal, electrical, mechanical and metallurgical mutual coupling, meanwhile its’ low melting point, high thermal conductivity, and high linear expansion coefficient increased the welding quality control difficultly. Basing on SYSWELD, a numerical simulation of effects of welding current, welding time, thickness of plate, electrode pressure gauge and size on the nugget shape and welding quality of ZA31B was demonstrated. The relationship between the size of the nugget dimensions and the welding parameters was established by a large number of simulation and experimental study. The experimental results showed that the analogue result was consistent with the test results, and it could be used to guide the actual production.

Abstract: Based on the welding problems of 304 stainless steel serpentine flow industrial condensation plate, the three kinds of CO₂ laser welding procedures are adopted to manufacture the condensation plate. The optical microscope, SEM, EDS, micro-hardness and tensile tests are used to analyze the microstructure and micro-hardness of 304 stainless steel sheet joint. The relationships between the generated defects and carbide separation in the welding joint are discussed. Due to the grain refinement, the micro-hardness of welding seam is increased. Therefore, it is reasonable factors that the heat input, cooling velocity and temperature gradient to improve the defects of 304 stainless steel serpentine flowing channel industrial condensation board in CO₂ laser welding.