Applied Mechanics and Materials Vols. 148-149

Abstract: In this paper vehicle routing problem with stochastic demands and simultaneous delivery and pickup is developed and analyzed, which is an important expansion of classical Vehicle Routing Problem(VRP).An effective algorithm based on Important Sampling is designed to solve the model. The optimal importance sampling distribution function was obtained by making use of the expection constructed by likelihood ratio. Numerical experiments have been conducted and the results indicate that the method can effectively solve this problem.

Abstract: This paper takes bubbles of bubble shell as research object, mainly studies two bubbles arranged in a vertical position. Applying VOF (volume of fluid) method to simulate interaction between two bubbles, analyses the effect of center distances and diameters on deformation and coalescence of bubbles. Results show that coalescence time of two bubbles with same diameters increases as the center distance increases. To two bubbles with different diameters, when the bigger bubble located beneath at the initial time, the smaller bubble moves upward first and then moves downward before two bubbles coalesce. When the smaller bubble located beneath at the initial time, bubble coalescence cannot happen. This paper is the basis of bubble group research, it is of positive significance to the bubble group research and performance improvement of bubble shell.

Abstract: The objective of this paper is to consider the use of fractal geometry as a tool for the study of non-smooth and discontinuous objects for which Euclidean coordinate is not able to fully describe their shapes. We categorized the methods for computing fractal dimension with a discussion into that. We guide readers up to the point they can dig into the literature, but with more advanced methods that researchers are developing. Considerations show that is necessary to understand the numerous theoretical and experimental results concerning searching of the conformality before evaluating the fractal dimension to our own objects. We suggested examining a cloud of points of growth of fracture surface at laboratory using CATIA - Digitized Shape Editor software in order to reconstruct the surface (CAD model). Then, the author carried out measurement/calculation of more accurate fractal dimension which are introduced by [1] in the other paper as Part II.

Abstract: In order to reduce production cost of Fuel Cells, a new type of Pt/C membrane electrodes -- PtCu-LaO_x, LaO_x-PtCu and PtCu-LaO_x-PtCu composite multi-layer membrane electrodes -- would be raised, in which with developing different membranous layer form dispersed on the surface of carbonaceous or monocrystalline silicon substrates were manufactured by Ion Beam Sputtering technology. Phase composition, micro-area surface topography and elements of these electrodes were analyzed by X-ray Diffraction, Scanning Electron Microscopy combined with Energy Dispersive Spectrometry and Atomic Force Microscope, respectively. It was found that doping La could not only enhance Pt crystallization and decrease Pt grain size but also contribute to Pt(111) preferential orientation growing in the LaO_x-PtCu, and that biggish ratio of La(At%) : Pt(At%) in micro-area would be difficult of occurring particles reunion on PtCu-LaO_x surface, and that the orientation growing of Pt(200), Pt(220) and Pt(311) would be restrained in PtCu-LaO_x and PtCu-LaO_x-PtCu, and that the Pt alloy particle exhibited more homogeneous distribution and less size in PtCu-LaO_x-PtCu. Our study indicated that these new types of membrane electrodes could be used in Fuel Cells and make Fuel Cells as a new power source for electrical vehicles.

Abstract: All composite π joints, which can minimize structure redundancy and pave the way for much reduced assembly time, have been developed as a great achievement of the integrated structure technique. To obtain knowledge about the mechanics behavior of composite π joints after cycle loadings, especially residual strength, cycle fatigue test and tensile test for the joints are conducted. From this study, some significative remarks can be made: the strength of composite π joint has reduced slightly by fatigue crack; the residual strength and the general rigidity of the joint exhibit large scatter; the filler zones and tip zones are those of potential weakness in the joints, and the sample in residual strength test has similar failure patterns with that in static tensile test.

Abstract: This paper using the method of combining balance static calibration with finite element analysis research the change and distribution law, and analyze the influence of the law on primary coefficient of hinge moment balance measurement, in conditions of different fixed-end geometry size and different preloaded force of fastening bolt.

Abstract: The level of mobile shot blasting machine analysis, a mechanical model of the projectile with the blade and shot rounds of dynamic simulation model, the model by imposing constraints and external forces, analysis of air resistance, friction, blade length and projectile diameter of throw playing speed. Played by the speed of analysis can throw further analysis of various parameters on the effect of throwing fight.

Abstract: SiO₂ thin films were prepared on stainless steel substrate by RF reactive magnetron sputtering. Their microscopic surface morphology was characterized by atomic force microscope (AFM) and static contact Angle (SCA) was applied to evaluate hydrophilicity of films. It was found that SiO₂ thin films showed super hydrophilicity which could last long at Ar/O₂ ratio of 6:4; under such condition, substrate temperature also affects hydrophilicity of films, the best of which can be obtained at 90 °C.

Abstract: Constitutive model is useful to predict the final shape of sintered microsize structures. In this paper, the contribution of lattice diffusion (Nabarro-Herring creep) is considered and a constitutive model is established to simulate densification of 316L stainless steel microsize structures fabricated by micro metal injection molding. The predictive capability of the model is verified by comparing the theoretical calculations with the experimental results. The influences of boundary energy on modeling results are discussed. It is found that the modeling results agree reasonably well with the experimental results.

Abstract: An experimental study was performed to study crack shape evolution of 16MnR pressure vessel steel by adopted compact tension (CT) specimens under Mode I constant amplitude loading. A data and numerical analysis of crack shape were conducted and the stress intensity factors (SIF) along crack front were calculated. The results revealed that curve crack shape could be described by elliptic equation properly and was similar in the stable crack growth stage. The initial crack shape was straight at the notch root, so SIF of the center was bigger than that of the surface. When the crack shape was curve, SIF of the center was smaller than that of the surface.