Advanced Materials Research Vol. 815

Abstract: A fibrous monolith cemented carbide with WC-6Co as cell and WC-20Co as cell boundaries was produced through hot co-extrusion process in this paper. The density, hardness, bending strength and fracture toughness of the fibrous monolith cemented carbide were tested, and the fracture and crack propagation were observed by metalloscope and SEM. The results showed that the bending strength and fracture toughness of the fibrous monolith cemented carbides was remarkably improved 71.91% and 45.7% respectively, while the hardness was slightly decreased 1% compared with WC-6Co composites. It is the reason that the tougher shell WC-20Co with higher bending strength and fracture toughness can absorb more fracture energy, which can slow down and prevent the crack propagating from brittle core WC-6Co.

Abstract: A three-dimensional refined model of composite lining is built with the example of shield tunnel of Xijiang water diversion project in Guangzhou by using finite element software. Segment opening and steel pile deformation characteristics are analyzed. Necessity of light material and steel pile is detailed explained. The results show that the maximal segment opening of composite lining is 0.361 millimeter. The bolts are in elastic state and not appear plastic deformation, so segment without leakage. Steel pipe strain curve is approximate circular symmetry in whole circle. It is necessary to add light material and steel pile, because they can effectively reduce the stress of concrete and prevent cracking.

Abstract: In order to improve the mechanical properties of the polyurethane foams, the silica nanoparticles were added into the foams in the form of SiO₂/PEG suspension during the preparation process. The microstructure, density, static mechanical properties and dynamic mechanical properties of the foams were investigated. Microstructure analysis shows that the silica nanoparticles were uniformly dispersed in the foams, however when the amounts of SiO₂/PEG suspension is more than 2.5 wt.%, cracks in the skelecton were observed in foams. With the increased SiO₂/PEG suspension, the density, static compression strength and dynamic compression strength show an increasing tendency. When the SiO₂/PEG suspension is 2.5 wt.%, the density of the foams increased 4.17 %, while the static compression strength increased 26 %. When the SiO₂/PEG suspension is 10 wt.%, the density of the foams increased 16 %, while the dynamic compression strength increased 60.5 %. The corresponding mechanism was discussed in the paper.

Abstract: The effective strain size and distribution of Al-5Ti-1B alloy deformed by equal channel angular pressing (ECAP) were investigated through the finite element simulation by the die with outer corner ψ=0°, 20°, 30° and the friction coefficient f=0, 0.2, 0.3. The simulation results show that the effective strains decrease with the increase of the outer corner ψ from 0° to 30° with a constant f; the more uniform deformation were obtained under the conditions of large friction than that of small friction. Al-5Ti-1B alloy was produced by once path ECAP at room temperature under the die with the corner angle φ=90° and ψ=20°. The optical microscope and compressing test machine were performed. The results indicate that the grain size was obviously refined. The yield strength increased by 37.5% from 142.0MPa to 195.3MPa, and hardness increased by 24% from 45.2H_V to 55.9 H_V.

Abstract: Further research on constitutive model of RPC (Reactive Powder Concrete) restrained by steel tube under axial compression is analyzed based on the research on concrete-filled steel tube and RPC-filled steel tube at home and abroad. Finite element analysis on RPC-filled steel tube stub columns under axial compression is conducted with ABAQUS to analyze the confinement index, core concrete strength and contact property on ultimate bearing capacity of RPC restrained by steel tube. As the confinement index and the core concrete strength increasing, the bearing capacity of RPC restrained by steel tube increases. The model with frictionless contact form has greater bearing capacity, but the ductility decreases.

Abstract: The mechanical properties of FRP steel-reinforced concrete columns are discussed. We study the constitutive relation of the concrete, based on the model and the experimental dates for the control the size of affecting parameters. When using the used model, the experimental dates can be reanalyzed and corrected for the intensity correct formula of FRP column. The ultimate bearing capacities of FRP constraint rectangular column use superposition principle to calculate the strength calculation. The ultimate bearing capacity of FRP column is divided into two parts: we conclude the big eccentric bearing capacity calculators formula by the columns bend. Through the study of the column, we concluded that the eccentric loading little eccentric calculation formula of bearing capacity. A case though using the example of this formula is similar with experiments results of the data.

Abstract: A three dimensional model of connecting rod has been made and drawn meshes. The load and boundary conditions were determined and the stress was calculated with finite element software. Safety of connecting rod was discussed using the safe coefficient. The rod made of powder forging is better in mechanical and technological properties.

Abstract: To full understand engineering properties of soils on Boubyan island in Kuwait, some in-situ tests were performed along the highway and railway line, meanwhile some laboratory tests for soil samples from the different depth. It was concluded that its properties was low void ratio, low moisture content, low plasticity, low sensitivity, low permeability and high salt content. The soil classification belonged to CL and Marine-chloride-highly saline-soil.

Abstract: In order to obtain the influencing factors and behavior of the intrinsic length of clay in Tianhe District of Guangzhou, different specimens are fabricated by the mixing clay and quartz sand in Tianhe District. Using the triaxial shear test results, the intrinsic lengths of different samples are determined. The results show that the liquidity index of matrix has little effect on the intrinsic length. The intrinsic length increases linearly with increasing reinforcing particle content. The larger the content is, in reinforcing particle the larger the decrease is in intrinsic length. The intrinsic length decreases with increased reinforcing particle size.

Abstract: [Objectiv The aim is to study the extraction technology of melanin from banana peel, and discuss its stability. [Metho We used banana peel as raw material, the absorbance at 410 nm as the index, extracted melanin by base-acid method, and optimized the extraction technology by the single factor and orthogonal test. Then we discussed the melanins stability at different temperature, light source, pH value, metal ions, antioxidant and reducing agents.[Result The best extraction conditions of melanin is that, hydrochloric acid soak time 5 h, alkaline solution pH value 14, extracting time 20 min, extraction temperature 70 °C, absorbance value about 0.309 A. Melanin from banana peel is stable at high temperature, different light source irradiation, reducing agent coexist; but at room temperature, metal ions and oxidizing agent coexist, it is unstable. [Conclusio This study provided experimental basis for the optimization and development of melanin from banana peel.