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121.
高温后高强高性能混凝土双轴压力学性能 总被引:7,自引:0,他引:7
利用大型静动真三轴试验机,进行了常温20${^\circ}$C以及200${^\circ}$C$\sim $ 600${^\circ}$C\,6个温度等级高温后高强高性能混凝土在7种应力比双轴压应力状态下的强度与变形试验.测得了双轴主压方向的静态强度、峰值应变与应力应变曲线,剖析了温度和应力比对单、双轴压强度与峰值应变发展趋势的影响规律性以及试件破坏形态. 试验结果表明:随温度的升高,高强高性能混凝土的单轴压减摩强度并不一定降低;双轴压强度相对于单轴压强度的提高倍数取决于应力比、不同温度等级后的高强高性能混凝土``脆硬性'. 提出了带有温度和应力比参数的Kupfer-Gerstle破坏准则公式. 相似文献
122.
Z.F. Shi B. Huang H. Tan Y. Huang T.Y. Zhang P.D. Wu K.C. Hwang H. Gao 《International Journal of Plasticity》2008
A simple method is established to determine the microscale uniaxial stress–strain curve from the load and deflection data for a doubly clamped beam. The method is based on the fact that, for beam deflection much larger than the beam thickness, the axial stretching dominates the deformation in the doubly clamped beam and the doubly clamped beam behaves like a simple plastic hinge. The microscale uniaxial stress–strain curve, together with the cantilever beam experiments, is used to determine the strain gradient effect in Au thin beams. The effect of finite rotation is also discussed. 相似文献
123.
Oriented poly(ethylene-2,6-naphthalate) (PEN) has been characterised by polarised FT-IR spectroscopy to determine the structural angles of the transition moments to the molecular chain axis. The bands at 1130 cm−1, 1142 cm−1 and 1602 cm−1, which have been previously assigned as having their transition dipole moments parallel to the chain axis, are confirmed as parallel bands. Bands at 767 cm−1 and 831 cm−1 are confirmed as perpendicular bands. However the band at 1708 cm−1 which has previously been assigned as a perpendicular band, is shown here to have its transition moment at 72° to the molecular axis. 相似文献
124.
运用张量分析,证明了适合描述不可压缩黏弹性材料非线性本构关系的3种理论:BKZ理论、Lianis理论和Chirstensen理论,运用到各向同性材料中它们的单轴拉伸具有一样的表现形式,同时也验证了3种理论在解释非线性本构关系时具有统一性. 相似文献
125.
126.
The uniaxial perfectly matched layer (PML) method uses rectangular domain to define the PML problem and thus provides greater flexibility and efficiency in deal- ing with problems involving anisotropic scatterers.In this paper an adaptive uniaxial PML technique for solving the time harmonic Helmholtz scattering problem is devel- oped.The PML parameters such as the thickness of the layer and the fictitious medium property are determined through sharp a posteriori error estimates.The adaptive finite element method based on a posteriori error estimate is proposed to solve the PML equa- tion which produces automatically a coarse mesh size away from the fixed domain and thus makes the total computational costs insensitive to the thickness of the PML absorb- ing layer.Numerical experiments are included to illustrate the competitive behavior of the proposed adaptive method.In particular,it is demonstrated that the PML layer can be chosen as close to one wave-length from the scatterer and still yields good accuracy and efficiency in approximating the far fields. 相似文献
127.
128.
We present a simple and complete approach to determining the directions and amplitudes of rays propagating through arbitrary systems of homogeneous and/or uniaxial materials. In the process we extend the work of Gu and Yen to full generality. 相似文献
129.
W. S. Weiglhofer 《International Journal of Infrared and Millimeter Waves》1998,19(7):993-1005
Novel expressions for the depolarization dyadics in an axially uniaxial bianisotropic medium (AUBM) are presented. Explicit formulae for the depolarization dyadics are derived for cubical, cylindrical and spherical geometries and their dependence on the magnetoelectric coupling parameter is studied graphically. 相似文献
130.
M. Khler J. Zweck G. Bayreuther P. Fischer G. Schütz G. Denbeaux D. Attwood 《Journal of magnetism and magnetic materials》2002,240(1-3):79-82
Continuous films and nanostructures of atomically stacked epitaxial Fe(0 0 1)/Au(0 0 1) multilayers have been studied by soft X-ray and Lorentz microscopy as well as micromagnetic simulations. Domain imaging shows about 65 nm wide magnetic stripe domains, in which the magnetization is oriented perpendicular to the film plane. These results are confirmed by micromagnetic simulations, which also yield additional information about the internal structure of domains and walls. 相似文献