Advanced Materials Research Vol. 852

Abstract: This paper investigates the effect of the laser welding parameters such as laser power, welding speed on weld strength. A 30W fiber laser with wavelength 1064nm has been used to weld transparent and absorbing acrylics in lap weld configuration. The force at break of the lap welds was assessed on the Universal testing machine,the shear strength was calculated by dividing the force at break by the weld area. Weld fracture surfaces and weld cross-sections were also analyzed under microscope using reflected polarized light to qualitatively assess the weld quality.

Abstract: The ecological structures of some organisms that could resist environmental vibration naturally (such as dragonfly, woodpecker and legs of cursorial animals) uncovered by biologists inspire people a new approach to overcome the above problem. In this paper, a new shock isolation system consisting of a pedestal, a rubber layer, an air spring and a shearing viscoelastic damper is designed, fabricated, and characterized to avoid the performance deterioration and physical damage of mechanical manufacturing devices from external mechanical excitations. The nonlinear dynamics model of the platform is developed and the dynamic characteristics are analyzed using numerical analysis. The displacement and velocity response are obtained. The results demonstrate that the stiffness and damping characteristic of the platform change with excitation frequency. The vibration isolation effectiveness will be greatly enhanced.

Abstract: This paper base on the actual form and structure of the original bridge piers actual data, according to the exposure collision theory and nonlinear finite element analysis theory, using LS-DYNA software, research the realationship of drift ice strength, modulus of elasticity, thickness factors with affecting convection ice impact force, while the drift ice impact force impact of the bridge was tested and simulated contrast. Simulation results show that the impact force with the flow of ice floe strength, elastic modulus, the increase of the thickness of the ice sheet was an increasing trend.

Abstract: Titanium Alloy Ti-1023 is widely utilized in aerospace industry; the integrity of the parts machining surfaces is of critical importance for aerospace industry. Surface roughness, microstructure and microhardness variations were investigated on a CNC machining at different cutting speeds. Experiments results showed machined surface integrity of Ti-1023was sensitive to cutting speed. The roughness of machined surface raised with increase of the cutting speed from 40 m/min to 100 m/min, but decreased while the cutting speed increase from 100 m/min to 300 m/min. It can also draw the conclusion that no significant phase transformation, no obvious deformation and no white layer on subsurface microstructure can be observed. As for microhardness, it can also be seen that the machined workpiece surface was not seriously hardened, less than 35μm depth of work hardening at different cutting speed.

Abstract: The crystallinity of the isotactic polypropylene during rolling is measured by the wide angle X-ray method. And then the influence of the crystallinity and true rolling strain on the work hardening is analyzed comprehensively. The work hardening index of the crystallinity part is 2, and the index of the amorphous part is 4. Deformation in the crystallinity part is more difficult than the amorphous part; however, the work hardening rate is smaller. The work hardening contribution of the crystalline part is higher than the amorphous part in the early rolling stage, but lower as the true strain is higher than 1.0.

Abstract: The activated carbon fine particles, as damping agents, are filled into the impact damper. With experimental method, the performance of the fine particles impact damper to the main system is compared with the multi-unit impact damper. The results indicate that the damping effect of the impact damper with activated carbon fine particles is not better than that of the multi-unit impact damper, but it has a much better effect to restrain the strong nonlinear of response than the multi-unit impact damper. In a certain resonance region, there is an optimum particle filled rate to the fine impact damper.

Abstract: Based on the heat-resistant mechanism, the orthogonal experimental method and the requirements for physical-mechanical performances of heat-resistant concrete, one mixing process project was taken as the target for analysis on the mixture ratio design of heat-resistant concrete. The conventional raw materials such as normal Portland cement, common crushed aggregates, fly ash and concrete admixture were adopted to manufacture the C30 heat-resistant concrete which gets the limit heat-resistant temperature of 500°C subsequently. And the influencing factors on the strength of heat-resistant concrete were also studied in this paper. Experimental results show that the mixture ratio design of heat-resistant concrete in this paper is reasonable. The engineering application results also show it is financially viable that adopting the normal Portland cement to manufacture the heat-resistant concrete with limit heat-resistant temperature of 500°C.

Abstract: Melt blowing is an important method for producing ultrafine fibers. In melt blowing process, compared to the studies on the fiber path at a certain air pressure condition, much less has been done on searching the evolution of the fiber paths at different air pressures. In this study, a high-speed camera was used to capture the fiber paths below a slot die and a swirl die in the melt-blowing process. The evolution of the fiber paths was captured. This paper first shows the evolution of the fiber paths at different air pressures, which is useful to further understand the attenuation effect on the fiber in the melt-blowing process.

Abstract: A numerical model using VOF method is developed to describe the phenomenon of a hollow droplet impact on a flat surface including spreading, retardation, recoil and first and secondary break up. The proposed model is verified by literature experiments. Some new hydrodynamic characteristics have been found. The mechanism of central counter jet is explored according to pressure distribution and velocity vectors inside droplet. The relationship between impact features of droplet and deposition parameters is highlighted. In order to investigate the heat transfer rate at the gas-liquid interface, air entrapment and gas cavity are discussed.

Abstract: Based on a large number of actual production data, the paper researches the hydraulic characteristics of high water cut crude oil pipeline in Sabei Oilfield and summarizes change rules of Hydraulic friction coefficient and Reynolds number of high water cut crude oil pipeline under different flow states. After making correction model of Hydraulic friction coefficient at different flow states and using the optimization technique to determine the coefficient in the model, based on C++ builder programming platform developed the software of pipeline hydraulic friction coefficient of correction. The results calculated from the software show that the correction model can significantly reduce the pipeline hydraulic calculation errors which are declined from more than 20% to less than 5%.