Applied Mechanics and Materials Vol. 274

Abstract: The compression test on TC21 titanium alloy was carried out in the temperature range of 860~940oC and the strain rate range of 0.01~10s-1 on Gleeble-1500D hot simulation machine. And the hot deformation behavior was studied. The processing map was calculated and analyzed according the dynamic materials model. It is found that the flow stress of TC21 decreases with the increasing of the temperature and the decreasing of the strain rate. The flow stress curves are characterized by steady state at low strain rate( s-1）but discontinuous yield at high strain rate( s-1). The processing map established at the true strain of 0.4 shows that there are three regions, instability and safe and peak region, and the efficiencies of power dissipation are 0~25%，31%~37% and 43%~49% respectively. The peak region is the optimum hot working zone of TC21 titanium alloy.

Abstract: Superparamagnetic core/shell nanoparticles have been prepared successfully by the reduction of Au3+ onto the surface of superparamagnetic nanoparticles. The core/shell nanoparticles were characterized by Transmission electron microscopy (TEM), X-ray powder diffraction patterns (XRD), UV–vis spectrophotometer, Vibration Sample Magnetometer(VSM) and micro-confocal Raman system. The results revealed that the prepared core/shell nanoparticles were covered by Au shell. These superparamagnetic nanoparticles can be highly sensitively detected and afford new opportunities for biomedical applications through chemical bonding of bioactive molecules with the Au shell of nanoparticles.

Abstract: This paper describes the whole modeling process of bone fracture fixture of micron wood paring, during which, positional parameters of the plates are calculated by formulas based on the three base planes of the fixtures plate, then after analyzing these positional parameters, the conclusion is tuning parameters of the plate should be determined according to human’s height. After that, Korean pines from Lesser Xing′an are chosen as the source for wood in the experiment, after cell lysis and long wood paring molding, the new fixture material of micron wood paring is created with much higher density than the original wood, very low expansivity after water absorption and almost no change after 24 hours’ immersion in water.

Abstract: The target of the paper is to study the method of extracting polysaccharide containing selenium from Hericium erinaceus by using the method of water extracting-alcohol precipitating. The objective is to determine the best technological condition of the extraction process of selenium polysaccharide in hedgehog fungus. Method: applying an atomic absorption spectrophotometry to detect the content of inorganic element in selenium-rich hedgehog fungus; employing the 2, 3-diaminonaphthalene fluorescence spectrocolorimetry to detect the selenium content in the selenium-rich hedgehog fungus; using phenol-sulfate method to detect crude polysaccharide. Conclusion: we have presented three simple detecting methods with advantages of low sampling volume, little interference to analyze and reliable results; therefore, the methods are worthy of popularizing and using.

Abstract: Based on the finite element analysis software AdvantEdge, a simulation model for the milling process of aluminum alloy 7075-T7451was established to research the cutting temperature. This simulation model predicts the temperature distribution of work-piece and cutting tool, and the temperature variation trend along with the milling speed and rotational speed. The simulation results provide valuable references for researching on machining mechanism.

Abstract: The common indoor air purification materials that are activated carbon, enzyme, and photocatalyst in China are introduced in this paper. The characteristics and present research states of typical air purification materials are reviewed. The composites will be the focus in the future.

Abstract: Ferromagnetic base composite material is widely used in aerospace field, and its high pressure mechanical properties become the study hot spot in recently years. Aimed at an advanced ferromagnetic base composite material, its impact compression behaviors were investigated by means of Light Gas Gun (LGG). The shock wave velocity (D) and the particle velocity (u) behind the shock wave were measured and calculated by using Asymmetry Impact and Direct Measurement. Based on the experimental results and calculated results, a D-u type Hugoniot curve was obtained. The Grüneisen equation of state for the ferromagnetic base composite material and its coefficients were obtained on the basis of its Hugoniot curve.

Abstract: The wear resistance with non-smooth surface was studied by the method of orthogonal design using MG-2000 wear test machine. The model specimens made of W9Cr4V high speed steel with regular concaves were processed by Laser texturing technology. Temperature, concave diameter and concave distance were taken as test factors, each factor selected 2 levels. The test results show that temperature is the biggest influence on wear resistance of non-smooth concave specimen, concave diameter is secondly, the concave distance is not obvious. The test results provided preliminary experiment data for the selection of non-smooth surface size and density distribution.

Abstract: This paper presents an experimental investigation of aluminum alloy H-type sections subjected to axial compression between two pinned ends. The specimens were fabricated using 6082-T6 heat-treated aluminum alloy. 26 material tensile tests were performed then a test program included 12 column tests which were separated into 6 test series of different geometry and ranged from 990 to 1840 mm in length in order to obtain a column curve. All the observed failure modes for the column tests were overall buckling and the axial capacities were obtained.

Abstract: Strength and ductility data for Q235A steel from 20 oC to 950 oC was obtained from a series of experimental tests. The stress rate sensitivity was studied by conducting Split-Hopkinson Tension Bar (SHTB) test and uniaxial tension test on smooth cylindrical specimens while the influence of stress triaxiality on ductility was revealed by conducting upsetting tests, tension tests on pre-notched cylinder specimens and torsion tests on SASs. Slightly modified versions of the two Johnson–Cook (J–C) models describing flow stress and fracture strain are presented to characterize the properties of Q235A steel as function of strain rate, temperature and stress triaxiality. Corresponding model parameters were calibrated based on the test data and with the help of finite element calculation. It was found that the modified Johnson–Cook (MJC) models give more close predictive results compared with the original J–C models.