Advanced Materials Research Vols. 1004-1005

Abstract: A membrane-beam-elastic element mechanical model of a lightweight composite heavy roadway, which is used on soft slimy ground, is built and its mechanical behaviors under loads are simulated by a large commercial finite element analysis software. The structural style which deformation is minimum under same loads is found, and numerical results are accorded with test ones, can meet the required precision and show reliability of the numerical calculation model. The commercial software can be used to simulate actual static strength situation of the lightweight composite heavy roadway and explore structural style of new roadway. Research shows that lightweight composite heavy roadway which can guarantee heavy vehicles pass in the soft slimy ground conditions make a significant technological breakthrough.

Abstract: For different technical reasons, cutouts such as holes in thin-walled structures are inevitable and are of significant technical relevance. Unfortunately open holes usually lead to an undesired stress concentration at the hole vicinity and a reduced load carrying ability of the structure. Therefore the mechanical properties of fiber-reinforced composite laminates with open holes are studied in the paper. The influences of the size and shape of the holes are investigated. A progressive failure finite element model is developed with software ABAQUS. Different failure modes of the composite laminates with various holes are simulated under the Hashin failure criterion. The computational results show that the hole/s have a significant effects on composite laminates properties, and the conclusion can be provided as a good reference for the design of the composite laminates with hole/s.

Abstract: The penetration characteristics of tungsten fiber reinforced metallic glass matrix composite with different tungsten fiber spacing were simulated by LS-DYNA programme. It is indicated that J-C constitutive model for describing deformation behaviour of tungsten fiber can accurately reflect the penetration process of the composite. The simulation results show that the composite has obvious self-sharpening behaviour, and its penetration performance is higher than tungsten alloy. The higher penetration performance depends on close-packing of tungsten fibers separated by metallic glass.

Abstract: For the copper-based composite friction material, the statistical models of the element structure were given in this paper to pick up the main components, that was, through the principal component analysis on basic element model of surface structure, the two kinks of main indicators or indexes are ascertained can be found from the original four indicators. Here, the main components were the area radio and long radius, the others among the four were short radius, inclination. Moreover, the indicator reduction criterion was put forward as a general rule by this paper.

Abstract: A series of HXNBR/SHPF composites were fabricated and sound absorption property was investigated. The results showed that with increasing of SHPF proportion the sound absorption coefficient was raised. The composite sound absorption coefficient with thickness of 1mm is 0.385, 0.438 and 0.535 at frequency 2500 Hz when the SHPF proportion is 10%, 20%, 30%, respectively. The HXNBR/SHPF composite sound absorption property could also improved by increasing the composite thickness with constant fiber proportion. The composite with thickness of 2mm and SHPF proportion is 10%, 20%, respectively. The sound absorption coefficient increased from 0.385 to 0.427 and 0.438 to 0.475 at frequency 2500Hz, respectively. The mechanical property also improved with increasing of SHPF proportion. So, the HXNBR/SHHPF composite has potential practical application value.

Abstract: For an copper-based composite material, the two statistical classification methods were given in this paper according to their radios of graphite, 10%and 20%, through the element modelling indexes of the corresponding surface microstructure. At first, whereas the numbers might not be straightway convenient for statistical classification, so the principal component analysis would be introduced for reducing the number of indexes. Thus, under the indexes reduced, the both advantages and disadvantages of two statistical classification discrimination methods were discussed.

Abstract: Using the method of composite material complex and constructing new stress functions with complex singularity exponents, the problem of singularities near interface crack tip for mode II of orthotropic bi-material is studied. Boundary value problems of generalized bi-harmonic equations can be solved with the help of boundary conditions, then four kinds of stress singularities are deduced, respectively, such as the constant singularity at λ=-1/2, the non-constant singularity at λ=-1/2+ε , the constant oscillation singularity at λ=-1/2+iε, and non-constant oscillation singularity at λ=-1/2+c+iε. For each case, the analytic expressions for stress intensity factors near the central-penetrated interface crack tip for mode II of orthotropic bi-material are obtained.

Abstract: A series of ZnFe2O4/expanded graphite composites (EG/ZF) were prepared by the chemical precipitation method. The structure, composition and morphology of the as-prepared samples were characterized. Taking methylene blue (MB) as the simulate organic pollutant, the influences of various factors on the decontamination of the as-samples and their reusing performance were researched. The results showed that the decontamination activity of the EG/ZF composite with mass ratio of EG to ZF equal to 0.8 reaches the maximum in the MB solution of pH = 5, and has good performance for repeated use. What’s more, the possible mechanism of decontamination was studied further.

Abstract: Fiber reinforced composite has been studied and exploited for its excellent mechanical properties, low cost, and outstanding durability for many years. Traditional sluice gates are generally heavy, clumsy, and susceptible to corrosion. The application of fiber reinforced composite is an appealing alternative, which is cost-saving and environmental friendly. Proper design can make the new material gate maintain good mechanical performances and easier to install.

Abstract: Using SiC particles and powder, the modified Si and α-Si₃N₄ powder as the main raw material, Si₃N₄-SiC composite materials have been fabricated by gelcasting. The Si₃N₄-SiC suspension with 75vol% (volume fraction) solid loading exhibits shear thinning rheological behavior under a shear rate from 10 to 160s^-1, which meets the requirement of the gelcasting process. The bulk density of the green bodies after solidification is 2.57 g·cm^-3 and the flexural strength 16 MPa, the green bodies have a dense and uniform structure. The bulk density and flexural strength of the Si₃N₄-SiC composites after nitriding are 2.67g·cm^-3 and 48 MPa respectively; the strength is higher than that of other industrial products without gelcasting. Well-developed intertwined fibrous Si₃N₄ crystals grow on the surface of the SiC particles to form a tight microstructure in the Si₃N₄-SiC composites after firing.