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991.
This paper is concerned with an homogeneous isotropic linear elastic strip, in plane strain. It is supposed that its lateral
boundaries are displacement-free and that the deformation is generated by actions on the ends. A cross-sectional measure of
deformation, complementing that of a previous paper, is defined and shown to satisfy a generalised convexity condition in
the axial variable x
1, for materials with negative Poisson's ratio σ. An enhanced measure is subsequently defined, and, in the case of a semi-infinite
strip, is shown to yield pointwise exponential decay estimates for both the axial and the transverse displacement components
for materials with positive Poisson's ratio.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
992.
本文研究了非惯性参考系中弹性薄板在范围运动与变形运动相互耦合时的1/2亚谐共振分岔,在建立了该系统的动力学控制方程的基础上,利用多尺度法得到了参数激励与强迫激励联合作用下非惯性参考系中弹性薄板1/2亚谐共振时的分岔响应方程及其分岔集,讨论了该动力系统的稳定性,给出了它的五种分响应曲线。 相似文献
993.
非圆截面弹性细杆的平衡稳定性与分岔 总被引:3,自引:1,他引:2
本文研究存在初始曲率或挠率的非圆截面弹性细杆的平衡及稳定性问题,在两端受力矩单儿作用的条件下,杆的平衡微分方程可转换为用欧拉角表述的一阶自治系统,并有可能利用相平面的奇点理论分析弹性细杆平衡状态的稳定性,文中对杆截面的对称性,以及杆的初始曲率和挠率对平衡状态性的影响进行了定性分析,导出了解析形式的稳定性判据,揭示了杆平衡状态的列态分岔现象。 相似文献
994.
ON THE ORIENTATION OF BUCKLING DIRECTION OF ANISOTROPIC ELASTIC PLATE UNDER UNIAXIAL COMPRESSION 总被引:1,自引:0,他引:1
Zhang Yitong 《Acta Mechanica Solida Sinica》2001,14(2):130-137
The theory of small deformation superimposed on a large deformation of an elastic solid is used to investigate the buckling
of anisotropic elastic plate under uniaxial compression. The buckling direction (the direction of buckling wave) is generally
not aligned with the compression direction. The equation for determining the buckling direction is obtained. It is found that
the out-of-plane buckling of anisotropic elastic plate is possible and both buckling conditions for flexural and extensional
modes are presented.
As a specific case of buckling of anisotropic elastic plate, the buckling of an orthotropic elastic plate subjected to a compression
in a direction that forms an arbitrary angle with an elastic principal axis of the materials is analyzed. It is found that
the buckling direction depends on the angle between the compression direction and the principal axis of the materials, the
critical compressive force and plate-thickness parameters. In the case that the compression direction is aligned with the
principal axis of the materials, the buckling direction will be aligned with the compression one irrespective of critical
compressive force and plate-thickness.
Project supported by the National Natural Science Foundation of China (No. 19772032). 相似文献
995.
996.
用不同模量有限元分析坝体应力和变形 总被引:7,自引:0,他引:7
探讨拉,压不同模量有限元法在重力坝应力,变形分析中的应用,利用该方法计算坝体裂缝,接触,稳定问题明显地提高了分析精度,本指出,给定拉伸时的弹性模量和泊松比是重要的可能的。在岩土力学,冰力学,陶瓷和塑料的力学分析中,使不同模量有限元法必定会有实际意义。 相似文献
997.
航空有机玻璃高阶弹性常数超声测定 总被引:2,自引:0,他引:2
从有限变形弹性动力学理论出发,认为超声在经历初始静态形变的各向同性弹性体中的传播是叠加在有限变形上的微小扰动,假设应变是应力的三次函数,导出以材料高阶弹性柔度系数为参数的超声纵波传播速度与初始应力关系式,针对YB-3航空有机玻璃试件,通过一组应力-速度测量数据,利用非线性最小二乘法优化方法确定了该材料的前四阶弹性柔度系数,并对实验及模拟计算结果进行了讨论。 相似文献
998.
Elastic properties of a thermal barrier ceramic coating composed of an NiCoCrAIY bond coat and a ZrO2(Y2O3) top coat were measured by a four-point bending rig in the temperature range 20°C–900°C. Different types of specimens (i.e., with bond coat only or with bond coat and top coat, on one side or on both sides) were employed. Test procedures were based on the theory discussed in Part 1 to enhance accuracy and to estimate confidence intervals. In particular, the method employed at high temperature was calibrated at room temperature by comparing the results with those obtained by methods with low sensitivity to layer thicknesses. For the bond coat, Young's modulus was found to be temperature independent up to about 500°C; a decreasing trend was observed above this temperature. For the top coat, a slightly temperature range examined. A possible explanation is given on the basis of phase transformation and the microstructure of the two layers. At room temperature, Poisson's ratio for the bond coat was found to be near 0.3, whereas a near zero value was measured for the top coat. 相似文献
999.
基于极大似然估计的BP算法及其在深基坑开挖参数辨识中的应用 总被引:2,自引:0,他引:2
本文采用人工神经网络BP算法对深基坑开挖工程中的参数进行辨识,将某些现场实测值作为网络输入,土层物性参数作为网络的输出, 限元计算取得学习样本来训练网络,从而地深基坑开挖工程中的参数进行辨识的目的,同时,本文提出了将极大似然估计引入BP学习算法中,可以考虑学习样本和网络输入(现场产测值)的误差,可以求得所辨识参数的可靠度,本文还对动态调整BP学习算法的学习速度因子,冲量系数以加快网络学习速度的算法进行了研究,本文算例表明本文算法训练速率可比传统BP算法快10倍以上。 相似文献
1000.
C. COLLARD 《数学年刊B辑(英文版)》2001,22(3):307-324
This paper gives all the two-dimensional membrane models obtained from formal asymptotic analysis of the three-dimensional geometrically exact nonlinear model of a thin elastic shell made with a Saint Venant-Kirchhoff material. Therefore, the other models can be quoted as flexural nonlinear ones. The author also gives the formal equations solved by the associated stress tensor and points out that only one of those models leads, by linearization, to the “classical“ linear limiting membrane model, whose justification has already been established by a convergence theorem. 相似文献