Applied Mechanics and Materials Vols. 727-728

Abstract: Magnesium cement-based straw board is made of chloride-oxy-magnesium concrete as gel phase, a new building material with straw as reinforcing phase. The effects of molar ratio of MgO and MgCl₂ on the static bending strength, softening coefficient and start time back to halogen moisture absorption of magnesium cement-based straw board are analyzed in detail. The result showed that,when n(MgO)/n(MgCl₂)=7(molar ratio),the mechanical properties and water resistance are the best, hydration products at this time is dominated by 518 phase.

Abstract: A fatal disadvantage of continuously reinforced thermoplastic composites is the high melt viscosity of the matrix which hampers impregnation. However, the melt viscosity of low molecular weight cyclic butylene terephthalate resin can reach extremely low value, which simplifies impregnation and even allows for the use of thermoset production techniques resin transfer moulding. To solve the problem of the glass fiber reinforced poly cyclic butylene terephthalate composites applied in the environment of high temperature, the specimens of composite laminates were tested under and after different temperature. It has been observed that the tensile properties of GF/PCBT composites decrease with increasing temperature between room 25°C and 150°C and tend towards stability after the high temperature.

Abstract: The network SiC ceramics was fabricated by combining organic foam impregnation and presureless sintering method. The co-continuous interpenetrating SiC/P₂₀ steel composites were fabricated by means of pressureless infiltration technique. The results showed that coarse surface of SiC ceramics with three-dimensional network structure was obtained and observed, which was halpful for the reaction of metal alloy during the impregnation process. The continuous interface could be detected in the SiC/P₂₀ steel composites.

Abstract: Through the ABAQUS software to simulate the compression performance of waste fiber recycled concrete column of the different fiber length and amount of fiber volume under the monotonic load, the ultimate carrying capacity and load - concrete strain curve of waste fiber recycled concrete eccentric compression column are concluded, and compare them with experimental results. The results show that the finite element analysis results and experimental results are basically in agreement with, which proves the feasibility and correctness of the finite element analysis.

Abstract: The microstructure and hydrophobicity of butterflywing surfaces were investigated by a scanning electron microscope (SEM), an atomicforce microscope (AFM) and a contact angle meter. The relationship between hydrophobicity,self-cleaning performance and microstructuralcharacteristic was analyzed. The butterfly wing surface is of lowadhesion (water SA 1~3°) and high hydrophobicity (water CA 138~157°). Theaverage rate of CaCO₃ pollutionremoval from the wing surface is as high as 86.2%. There is a good positive correlation (R²=0.873)between pollution removal rate and roughness index of the wing surface. The coupling effects of hydrophobic material andrough microstructure contribute to the complex wettability and remarkableself-cleaning property of the wing surface. Butterfly wing can be potentiallyused as a template for design of micro-controllable superhydrophobic surfaceand nano self-cleaning material. This work may offer inspirations forbiomimetic fabrication of novel interfacial material with multi-functions.

Abstract: There are good thermal conductivity, high luminous efficiency in the LEDs with metal substrates, which can effectively solve the problems such as poor heat dissipation、poor reliability of LEDs. The copper substrate LEDs have successfully developed with good performance by SemiLEDs, which indicates the direction of the high-power semiconductor devices for lighting.

Abstract: Al doped ZnO thin film have been prepared by a sol-gel method. The structural, and optical properties of the sample were investigated. X-ray diffraction and X-ray absorption spectroscopy analyses and UV absorption spectroscopy analyses indicate that Al³⁺ substitute for Zn²⁺ without changing the wurtzite structure. With the Al doping, the visible emission increased and the UV emission decreased, which is attributed to the increase of O vacancies and Zn interstitials.

Abstract: An effective approach was used to disperse CdSe quantum dots (QDs) into epoxy matrix and prepare highly transparent luminescent CdSe–epoxy nanocomposites. Dodecylamine-capped CdSe QDs were obtained through self-assembly of carbon chains of as-synthesized QDs and dodecylamine. It was found that dodecylamine-capped CdSe QDs demonstrate a homogeneous dispersion within epoxy matrix, thus the prepared CdSe–epoxy nanocomposites expressed transparence in the visible region and also light-emitting.

Abstract: Inthis investigation, the rare-earth oxide Yb₂O₃ combined with Al₂O₃served as sintering additives and SiC and B₄C powder were applied to fabricate SiC/B₄C multiphase ceramics composites by pressureless sintering. The results proved thatcombination of Al₂O₃ and Yb₂O₃ sinter additives were effective fordensification of SiC/B₄C composites. The influence of oxidation time onthe phase constitution, micro-structure and oxidation behavior of SiC/B₄C composites was investigated.Theformation of eutectic phase Yb₂Si₂O₇ phase waswrapped on the SiC surface and it reduced further oxidation of SiC particles.The oxidation kineticcurves followed a parabolic rule.

Abstract: The selection of an adequate friction model is an important aspect inthe finite element modeling of machining. Previously, different friction modelshave been compared, but the influence of the constitutive model or theworkpiece material have not been considered. This article focuses on theinfluence of the material and the constitutive model on the evaluation of thefriction model in machining. Numerical experiments are performed on threedifferent materials using different constitutive models. For every combinationof material and constitutive model, several simulations using different Coulombcoefficients, but the same cutting parameters, are performed. Several variablesare evaluated: cutting force, shear plane angle, chip-tool contact length,maximum temperature and maximum stress. The results reveal that the workpiecematerial plays an important role in the evaluation of the friction model. Theyalso show that there is significant influence from the constitutive models oncontact length, curvature ratio and chip thickness.