Applied Mechanics and Materials Vols. 66-68

Abstract: Microstructure evolution behavior of 1235 aluminum alloy under different deformation conditions was studied by hot compression simulation, along with OM, TEM. The law of microstructure evolution at hot deformation was also analyzed. The results showed that the dynamic recrystallization behavior of 1235 aluminum alloy was obvious during hot deformation. At higher deformation temperature or lower strain rate, the grain dislocation density was lower and grain boundaries tended to be straighter, therefore, the grains dynamic recrystallized more adequately. The recrystal grains were smaller and distributed uniformly at deformation temperature for 400°C and stress rate for 0.1s^-1 with the average grain size for 54.03μm.

Abstract: Leucite crystal was prepared using SiO₂-Al₂O₃-K₂CO₃-Na₂CO₃ as raw materials and adopting melt quenching and appropriate heat treatment temperatures. The crystal was characterized and analyzed by X-ray powder diffraction, the coefficient of thermal expansion, and biocompatibility. The results showed that appropriate Na₂O could advance the growth of leucite, but high concentration facilitates the formation of KAlSiO₄ crystal. The coefficient of thermal expansion was 24.52×10^-6/°C at 600 °C, and thereby the coefficient could be adjusted by adding appropriate amount of leucite. The biocompatibility of leucite was almost the same as the Songfeng powder for clinical applications.

Abstract: Electric arc praying technology was used to produce Fe/B-Fe coating on the carbon steel substrate. The microstructures was studied by means of scanning electronic microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and electron probe microanalysis (EPMA). Mechanical performances, wear resistance of coating were tested . The results showed that the resistance to abrasion and corrosion of Fe/B-Fe coating was respectively 16 times and 5 to 6 times higher than those of bare metal.

Abstract: In this work, the natural diffusion method and rapid chloride ion penetration method (RCM) are used to study the performance of polyaspartic aster (PAE) coating in marine structures protection. The ability of concrete resistance chloride ion permeability in marine environment is tested by such two methods. The results obtained by the two methods are compared, they agree well. The paper also study the change chloride ion permeability coefficient of marine concrete with different coating thickness and use scanning electron microscopy (SEM) to microscopic analysis. From microscopic research, only a few tiny holes appear in the sample section after 6 months corrosion. Compared with the samples without corrosion, the PAE coating still remains homogeneous and dense.

Abstract: In this paper, Kernel Fisher discriminant analysis and affine moment invariants are presented for recognizing the reference points on fabric surface. The planar images and spatial images of reference points that are indexed and attached on fabric are acquired by camera at different angle and focus, subsequently, the binary image of reference points are extracted by a series of algorithms such as filter, enhancement and binaryzation etc. Experimental result shows Kernel Fisher discriminant analysis has the better recognition ratio than routine nearest distance discriminant method. Correction recognition of reference points is the important step for the matching of multi-images and reconstruction of fabric surface morphology which provide the more information for fabric drape performance evaluation.

Abstract: In order to study the influence of anti-mite and antibacterial fibers content on the anti-mite property of fabrics, yarns of antibacterial moisture absorption & perspiration elimination fibers, photocatalytic moisture absorption & perspiration elimination fibers and their blended yarns with hemp fiber, bamboo fiber, Tencel, cotton fiber were selected, and six sets of samples were manufactured. The anti-mite properties of these six fabrics were tested with the repellent method and analyzed, the relationship between the content of these two anti-mite and antibacterial fibers and the anti-mite property of fabrics was obtained. The experimental results indicated that with the content of anti-mite and antibacterial fibers increasing, the anti-mite property of fabrics improved gradually. When the content of antibacterial moisture absorption & perspiration elimination fiber was 100%, the repellent rate of the fabric for dust mite was 80.51%; when the ratio of photocatalytic moisture absorption & perspiration elimination fiber and bamboo fiber in fabric was 65/35, the repellent rate of the fabric for dust mite reached to 82.05%, the two kinds of fabrics both owned better anti-mite performance. The conclusions from this research can be used as a reference to design and develop fabrics for home textiles with better anti-mite effect and comfortability.

Abstract: A computational model, which can reveal the out-plane size variation of sandwich panel unit cell, is proposed to study the out-plane size effects of honeycomb sandwich panels. In this model, the three dimensional unit cell of sandwich panel, consisting of the upper and the lower skins and the homogenized core, is constructed based on homogenization method. Three methods, i.e., homogenization method, the finite element method and the classical laminated plate theory, are used to study the influences of the out-plane size variation on the bending effect and vibration response of sandwich panel. Numerical results show that the solution of finite element method agrees with that of laminated plate theory when the number of out-plane unit cell is small. However, once the number of out-of-plane unit cell is large enough, the finite element solution is close to the homogenization results.

Abstract: A three-dimensional linear instability analysis was carried out for an annular swirling viscous liquid jet with solid vortex swirl velocity profile. An analytical form of dispersion relation was derived and then solved by a direct numerical procedure. A parametric study was performed to explore the instability mechanisms that affect the maximum spatial growth rate. It is observed that the liquid swirl enhances the breakup of liquid sheet. The surface tension stabilizes the jet in the low velocity regime. The aerodynamic force intensifies the developing of disturbance and makes the jet unstable. Liquid viscous force holds back the growing of disturbance and the makes the jet stable, especially in high liquid velocity regime.

Abstract: In this paper, the immune genetic algorithm (IGA) is used to optimize the compositions of the Al₂O₃/SiC/Ti(C,N) ceramic composite material. Corresponding to the optimal mechanical properties such as fracture toughness, hardness and flexural strength, the optimum material compositions have been achieved. The convergent speed of IGA is faster than that of the single immune algorithm, and the number of iteration is also reduced obviously. As a result, the efficiency of optimization is increased.

Abstract: In order to improve the utilization of K424 alloy, Z-Cast analysis software is used to get three-dimensional flow field and temperature coupling simulation in the process of K424 alloy castings filling, by considering the effection of pouring temperature, casting speed, shell thermal conductivity and temperature on the morphology of filling.A three-dimensional simulation of temperature changes in solidification process of molten metal was performed based on the filling simulation. The simulation results on flow field and temperature field shows the order of filling and solidification in different parts of the casting ,and determines the position where cold shut and misrun appears, which provides theoretical support to the improvement of technology plan.