Materials Science Forum Vols. 704-705

Abstract: Phyllostachys heterocycla begins to be used for black bamboo with high added value. However, the pyrolysis products were severely wasted. Therefore, the chemical components from Phyllostachys heterocycla were identified by TD-GC/MS after concentration. The main constituents of 150°С volatiles were acetic acid (46.75%), carbon disulfide (4.90%), 2-furanmethanol (4.10%), benzofuran, 2,3-dihydro-(3.63%), formic acid (3.27%), 2-propanone, 1-hydroxy-(2.80%), 2-propenoic acid, 2-hydroxyethyl ester (2.64%), dimethyl ether (2.15%), .beta.-pinene (1.84%), camphor (1.71%), etc. The main constituents of 180°С volatiles were acetic acid (20.66%), benzofuran, 2,3-dihydro-(14.49%), furfural (8.86%), formic acid (8.37%), 2-furanmethanol (4.17%), 4h-pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl-(3.74%), 2(5h)-furanone (2.83%), 2-propanone, 1-hydroxy-(2.74%), etc. The main components of pyrolysis products of Phyllostachys heterocycla in heat charring could also be used as bioenergy materials, but were not only abundant and healthy to human.

Abstract: The applications of sandwich structures in industry are numerous. The optimization of such structures with high strength and light weight have been the topic of interest for many researchers. There have also been a few studies on the vibration and sound transmission across these structures. This dissertation presents the structural and acoustic studies of sandwich structures for transport aircraft applications. The analysis of fully coupled structural-acoustic systems is presented in this paper. A method for the analysis of such coupled systems is developed using a particular solution approach. A simple two-dimensional rectangular cavity is used as an example to illustrate the solution approach in detail. Extensive numerical simulations have been done to investigate the effect of structural-acoustic coupling on the resonant frequencies and mode shapes of the system. The Galerkin and the Rayleigh-Ritz methods are used to obtain the coupled modal equations for the system which are solved using a state space formulation, which would provide the reference to the coupled structural-acoustic systems optimization.

Abstract: In order to improve microwave absorption properties of hollow ceramic microspheres (HCMs) and possess the better characteristics of “thinness、width、lightness、strongness”, used Al+Cr₂O₃ as the main reaction system, hollow ceramic microspheres were prepared by SHS flame quenching technology. Microwave absorption properties of HCMs were studied when the additive is Fe. The results show that microwave absorption properties of HCMs depend on the dielectric property of product, such as SiC、mullite, when there is no additive. However, when Fe is used as additive, the microwave absorption properties of HCMs are better. SHS reaction of agglomerate powders is happened in the flame field and SiC、Fe₂O₃、Al₃Fe₅O₁₂、Cr_1.3Fe_0.7O₃、(Fe_0.6Cr_0.4)₂O₃ are synthesized. Except the dielectric property of SiC, magnetic property of HCMs is possessed due to the ferruginous materials are synthesized. So its microwave absorption properties are stronger. Keywords: additive; hollow ceramic microspheres; microwave absorption properties

Abstract: The given work considers the influence of the power supply type (diode rectifier ВД-306 and upon new generation inverter Nebula-315) upon the chemical composition, microstructure, mechanical properties of the weld joints and health characteristics of the manual arc welding process.

Abstract: For the low launching noise and without increasing atmospheric pressure in chamber, the hydraulic energy accumulated torpedo launching device has been highly regarded by all navies around the world. Mathematical mode of the launch course of the device has been built. Combined with the tactics and technique index, the structure parameters of the device have been optimized with genetic algorithm. As several parameters which were different in degree and range, normalization was applied to convert multi-objective optimization into single-object optimization, and penalty function method was used to deal with constraints. The optimization result shows that the optimized structure parameters not only meet the requirement of launching, but the dimension of the device is more compact to fit the narrow configuration of submarine and may provide references to the design of hydraulic energy accumulated torpedo launching device.

Abstract: Piston of cam engines for torpedo works in terrible condition and always be caused fatigue breakdown by thermal load. In this paper, the thermal boundary condition of different piston parts are ascertained, such as the crown surface of piston and high-temp gas, the side of piston and cooling water, and the skirt of piston and cooling oil. Then the piston’s temperature field is obtained by using the finite element analysis software. This result provides the practical reference for further improving the structure and optimizing the design of the piston. Keywords: cam engine; piston; heat-transfer coefficient; temperature field.

Abstract: Strontium Titanate synroc samples were synthesized by combustion cynthesis (CS). Sr directly took part in the synthesis process. As a result, loading content issue is basically resolved. The products were characterized by density, microhardness X-ray diffraction, and scanning electron microscopy (SEM/EDS). The leaching rate was measured by the method of PCT. The results indicate that the Sr2+-SrTiO3 compound with high density, low leach rate and high property stability and the synthesis process is feasible in technology and economy. It can be concluded that the Strontium Titanate synroc is a perfect material to immobilize HLW Keywords: Strontium Titanate, high-level radioactive waste (HLW), immobilization, self –propagating high –temperatures synthesis (SHS).

Abstract: The complex stress function method is used in this study to formulate the 2-dimensional problem for nonhomogeneous materials. The Young’s modulus E varies linearly with the coordinate x and the Poisson’s ratio of the material is assumed constant and. The stress components and the boundary conditions are expressed in terms of two complex stress functions in explicit forms. It is noted that the constant term in stress functions has an influence on the stress components, which is different from the homogeneous material case. Subsequently, the problem of a nonhomogeneous plane containing a circular hole subjected to a uniform internal pressure is studied.

Abstract: This paper applies the fracture-mechanics-based analysis and the crack-closure concept to naturally occurring small cracks and large crack growth, and to make total fatigue life predictions solely based on crack growth from the assumed initial materials defect. The equation of total fatigue crack propagation life under constant amplitude loading is presented. And the total fatigue propagation lives of LY12-BCZYU aluminium alloy SENT specimens by this equation and validated by experimental results. Validation against calculations by the model and experimental data shows a good agreement.

Abstract: Using Realistic Failure Process Analysis Code RFPA^2D, a three layer materials model with a central layer and with the same thickness top and bottom layer, progressive formation of fracture saturation in multilayer materials is simulated in all case by numerical simulation. Our numerical simulation recurrence the phenomenon of fracture saturation in multilayer materials. numerical simulation shown that for the symmetric case the spacing of these fractures at fracture saturation are approximately the same and lineally related to thickness of the fractured layer. We investigate that the critical fracture spacing to layer thickness ratio is function of the thickness ratio of the top and bottom layers to central layer at fracture saturation. numerical simulation shown that for the symmetric case the critical spacing of fractures to layer thickness ratio decreases rapidly and tends to a constant value.