Applied Mechanics and Materials Vols. 249-250

Abstract: In finite element calculation of plastic mechanics, isotropic hardening model, kinematic hardening model and mixed hardening model have their advantages and disadvantages as well as applicability area. In this paper, by use of the tensor analysis method and mixed hardening theory in plastic mechanics, the constitutive relation of 3-D mixed hardening problem is derived in detail based on the plane mixed hardening. Numerical results show that, the proposed 3-D mixed hardening constitutive relation agrees well with the test results in existing references, and can be used in the 3-D elastic-plastic finite element analysis.

Abstract: We present a kind of surface plasmon interference phenomenon in two-slit structure. The simulation results show that the interference phenomenon will become more obvious for the two-slit structure with -shape slit than for the one with T-shape slit. And the interference effects can be improved by increasing the width of -shape slit shoulder. These results will be useful to design novel surface plasmon-based optical devices.

Abstract: We present the design and fabrication of metamaterials, and investigated the normalized power transmission properties of four metamaterials at different frequency in terahertz regime. We compared the power transmission performances of four types of metamaterials microstructures, and analyzed their transmission differences.

Abstract: The transient liquid-phase sintering behavior of micro-Zn/nano-Sn-3.0Ag-0.5Cu (SAC) pastes was examined at a temperature of 190 °C as a function of the volume of ultrafine (~12.4 nm) SAC nanoparticles present. SAC nanoparticles have lower melting point drop than the bulk SAC particles. Although successful linkage at the interface between all Zn particles was not accomplished in all sintered samples, the number of linkages increased marginally with a decrease in the SAC content. As a result, the electrical resistivity of the sintered samples decreased with the decrease in the SAC content; however, the resistivities were still very high in all samples. Microstructural observations indicated that the observed results were mainly due to the short lifespan of the liquid phase caused by the coarsening of SAC nanoparticles during heating.

Abstract: Spherical Bi particles were fabricated through a polyol synthesis using a zinc bismuth(III) carbonate precursor, and the effects of processing temperature and time on the morphology and composition of the resulting particles were evaluated. It was determined that longer processing times or higher processing temperatures resulted in the gradual conversion of as-formed bismuth hydroxide into spherical elemental bismuth via bismuth glycolate. The temperature for the effective synthesis of spherical Bi particles under these conditions was 230 °C

Abstract: In this study, the relationship between the impact performances of light-weight honeycomb sandwich composite panels with design parameters like panel cores and face’s thicknesses and materials, honeycomb foil thickness and cell size etc. are experimentally evaluated through the spindle falling tests. Analytical approaches are also carried out to confirm the validity of the experiments based on 3D modeling and using ANSYS LS-DYNA software. Comparisons of the experimental and analytical results are reported in this study.

Abstract: In the present work, the structure optimum design and simulation analysis of aluminum alloy automobile energy-absorbing components was carried out by using Finite Element (FE) method. The numerical simulations were carried out using the software LS-DYNA. Automobile energy-absorbing components usually was made a mental thin walled tube. In the paper, the tube was adopted aluminum alloy material. The FE model of the tube was validated by comparing the theoretical results and FE model results. The good correlation of results obtained show that the numerical analyses are reliable. Attention was focused upon finding an optimum cross- section shape of the tube in order to improve the crashworthiness. Several types of cross- section were studied and compared. Results show that the crashworthiness of the tube improved obviously when square cross section with the grooves was adopted.

Abstract: Currently, interest in nanotechnology concept for cement composites is steadily growing. Results of investigations of the concrete surface, reinforced with nanostructured mineral fibers by using atomic force microscopy (AFM) and dynamic ultra-micro hardness tester (DUMHT) of the specific areas of surface are presented. For comparison plain concrete and concrete with addition of single mineral fibers investigated as well. The analysis of the obtained data has shown that as a result of the directed microdisperse structurization provided by nanoinitiators on a surface of fibers, increase strength and deformation characteristics of a material. The main objective of this paper is to research the mechanisms of pattern formation surface of the concrete contained the High-modulus basalt microfiber (HMBMF) as a solid carrier for nanoparticles.

Abstract: The classical Fourier heat conduction law gives sufficient accuracy for many practical engineering applications. However, it cannot exactly reflect the real physical mechanism of heat conduction by highly-varying thermal load, at very low temperatures, or at nanoscale. The hyperbolic heat conduction equation can better explain heat conduction in solids. However, such equation is very difficult to solve. This paper studies the temperature field for a 1-D plate and a 1-D cylinder. The associated thermal stress for a 1-D plate is also given. Only in these simple situations, closed form solutions are possible and are given. The results can be used in the future analysis of thermal shock cracking and reliability analysis of materials in modern science and technology.

Abstract: 3%yttria-stabilized tetragonal zirconia polycrystal (3mol% Y2O3-ZrO2, 3Y-TZP) ceramic suffers from low temperature degradation (LTD) during long time use under hydrothermal condition. In this research, an attempt was made for monitoring hydrothermal degradation of the ceramic by using semi-nondestructive X-ray diffraction (XRD) method. In order to simulate accelerated hydrothermal degradation, the specimen was placed under water vapor atmosphere at 134°C, 150°C, and 200°C in an autoclave for various exposure time up to 40 hours. From the X-ray diffraction peak, two feature parameters including intensity ratio and full width at half maximum were determined and observed to increase with hydrothermal exposure time and temperature. The consistent changes in XRD parameters were correlated with the tetragonal-to-monoclinic microstructural change. Based on the established linear correlations with hardness reduction, potentials of the two XRD parameters were suggested for health-monitoring of the hydrothermally exposed 3Y-TZP ceramic.