Applied Mechanics and Materials Vols. 152-154

Abstract: A polymer solution is classified as non-Newtonian Fluid. The results of pressure data analysis for polymer flooding reservoirs would be inaccurate when generalized using non-Newtonian fluid flow models, which treat polymer solution as power law fluid. To improve analysis results, a study to create new pressure interpretation models for polymer flooding reservoirs is needed. First, this study presents a new viscosity model by considering diffusion and conduction. Then the model is applied to set up a new model of an injection well located at an infinite polymer flooding reservoir. The modeling solutions have been prepared through numerical iterations. An extended study has been done about the characteristics of the new pressure response curves.

Abstract: A kind of 1000MPa low carbon bainitic steel belonged to the Fe-Cu-Nb series was hot rolled and aged, the influence of aging temperatures on the microstructure and mechanical properties of the steel were investigated by using Scanning electron microscopy (SEM) and transmission electron microscopy(TEM). The results show that the microstructure of the low carbon bainitic steel consisted of lath-shaped bainite(LB), granular bainite(GB) and quasi-polygonal ferrite(QF), and the proportion of each kind of microstructure changed with the aging temperatures. The strength of steel with the increase of aging temperature first increased, then decreased, Aging temperatures had distinct effect on yield strength of the tested steel, and less effect on the ultimate tensile strength, we can get the best comprehensive properties yield strength 1011.87 MPa and elongation rate 16.38% of good tough match aged at 450°C. Through analysis it is concluded that the strength of the tested steels aged at 450°C reaches the maximum value, which is attributed to the precipitation of a large amount of fine ε-Cu particles(5~10nm) and a small number of(Nb,Ti)(C,N) precipitates.

Abstract: Abstract. Internal and/or external corrosions may frequently occur in pressurized pipes in offshore engineering components and many other industries. Corrosion defects reduce the collapse load of pipes, which can be improved by composite repairs. In this article, elastic-plastic finite elements analyses of pressurized repaired pipes with internal longitudinal flaws are performed to obtain the plastic collapse loads of them. The effects of composite patch geometries such as thickness and length on the improved collapse loads of repaired pipes are investigated. It is shown that the limit load of the repaired pipes may reach to the un-defected pipe by increasing the patch thickness (i.e. 25% of flaw depth for the pipe and patch material used in this study).

Abstract: In this paper, a simplified method is performed to predict the fatigue crack growth life of repaired pipes by glass/epoxy composite patches. For this purpose, an already developed automatic procedure by the authors is adapted to handle 3D crack growth analyses of repaired pipes subjected to internal cyclic pressure. The analyses are performed for offshore pipes made of low-strength steel containing an initial fatigue corrosion crack and repaired by glass/epoxy composite patch. Finally, an equation is presented here suggesting a point along the thickness of a repaired pipe in which, the calculated fatigue crack growth life based on the fracture parameters of that point in a simple uniform crack growth modeling along the pipe thickness (UCG) is almost equal to the calculated fatigue life in non-uniform crack growth analysis (NUCG) or a real crack-front modeling approach.

Abstract: According to the gelatification of sodium hydroxide ethanol solution, the chitosan (CS)/polyvinylpyrrolidone (PVP) composite hydrogel microspheres have been prepared in this paper. Meanwhile, the influence of PVP content and PH on the swelling property and the adsorption Cr(Ⅵ) effect of CS/PVP hydrogel microspheres has been also discussed. The results have shown that the introduction of PVP has significantly improved the swelling property of CS. When the CS content is 2.5% and the PVP content is 5%, the swelling rate of microspheres will be the maximum. The swelling property and the adsorption property of microspheres have shown certain pH sensitivity. And the SEM has also indicated that the inside of CS/ PVP composite hydrogel microspheres is the loose network structure, which is conducive to the swelling and the adsorption.

Abstract: The thermal conductivity of green teas has been used as engineering parameter in the design of processes and machines for drying, storing and aeration. The thermal conductivity of green teas was determined and its changes with moisture content, bulk density investigated. The thermal conductivity values of green teas increased from 0.036 to 0.438 W m^–1 K^–1 and from 0.041 to 0.568 W m^–1 K–1 for low and high (loose and dense) bulk densities, respectively, as the moist^{Superscript text}ure content increased from 5.3 to 78.7% dry basis. The change of the thermal conductivity of green teas with temperatures at different bulk densities shows that it increased from 0.035 to 0.045 and 0.042 to 0.053 W m^–1 K^–1, respectively, as the temperatures and bulk density increased. The thermal conductivity values obtained with the high bulk density was higher than those obtained with the low bulk density for green teas.

Abstract: High-speed milling (HSM) has advantages in high productivity high precision and low production cost. Thus it can be widely used in the manufacture industry. However, when the speed of spindle-tool reaches a higher speed range, the gyroscopic effect will become an important part of its stable milling. In this paper, a dynamics model of HSM system was proposed considering the influence of gyroscopic moment due to high rotating speed of end milling. Finite element model (FEM) is used to model the dynamics of a spindle-milling system. It obtains the trajectory of central point in face milling with considering gyroscopic effects through the dynamics model at high speeds. Then the cutting force model will be corrected by the trajectory of face milling. Then the stability lobes diagrams (SLD) was elaborated. Cutting thickness effects have non-negligible impact on stability limitation.

Abstract: TiO₂-Cu thin films containing 0 to 1%Cu coated on glass slides were prepared by sol gel-dip coating method. The prepared thin films were synthesized at the temperature of 400 ^◦C for 2 h with a heating rate of 10^◦C/min. The microstructures of synthesized TiO₂-Cu thin films were characterized by XRD, FT-IR and SEM. The photocatalytic activities of TiO-₂Cu thin films were tested using methylene blue (MB) solution under UV irradiation. Finally, the self-cleaning property was evaluated by means of contact angle of water droplet on the films. The results show all samples have the thickness in range of 1 um and surfaces are dense with a large surface area. It can be noted that TiO₂-1.0Cu thin films were found to give the highest photocatalytic efficiency and exhibited self-cleaning effect (small contact angle, 17°) under UV irradiation.

Abstract: The increased optical fiber development for a variety of physical and chemical measurements using smart structures and sensors leads to investigate the mechanical and chemical reliability of standard commercial acrylate polymer coated fibers. A comparison of mean failure strength of as-aged fibres to the water influence for similar exposure duration has revealed the highest sensitivity to dimethyl sulfoxide reagent (DMSO). SEM investigation revealed different damage levels in function of the aging conditions.

Abstract: Joining of dissimilar materials like Al alloy to carbon steel is attractive for industrial applications such as automotive industry. In this research, Friction Stir Welding (FSW) has been used to joint between dissimilar materials like 1100 Al alloys to AISI 1045 carbon steel. In this paper, the effect of rotational speed, feedrate and offset of tool are investigated on mechanical and metallurgical properties of the welding. The joints were evaluated by mechanical testing and metallurgical analysis. Metallurgical properties carried out by optical microscopy and Scanning Electron Microscopy (SEM) and mechanical properties conducted by the joint strength. Finally, optimum value of tool rotational speed and feedrate were obtained 710 rpm and 28 mm/min respectively and the best offset value of the tool obtained 1.5 mm in the Al alloy. Tensile strength properties of Al1100/1045 carbon steel joints were found to be approximately 20% lower than that of the Al 1100-H14 alloy base metal