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881.
平面应变不可压缩橡胶圆柱的大变形 总被引:5,自引:0,他引:5
针对一类新的橡胶材料应变能函数,推导了受内压作用下不可压缩橡胶圆柱的大变形公式,给出了位移、应力的解析表达式(用积分形式表示)。建立了适用于分析非线性不可压缩橡胶材料的罚有限元列式,算例表明:位移与应力能很好地与理论解吻合,并提出了控制计算稳定的方法,特别是详细地讨论罚因子的选取及对计算结果的影响。 相似文献
882.
衍射损耗耦合型高功率Nd:YAG激光器 总被引:1,自引:1,他引:0
本文提出并设计了适用于高功率固体激光器的新型谐振腔。使用腔内衍射滤波器以实现激光束高的光束质量,其衍射损耗作为耦合输出。实验上,获得了近衍射极限的100W量级激光输出。 相似文献
883.
On the use of nickel foil strain gages at varying temperatures 总被引:1,自引:0,他引:1
When a strain gage made of nickel foil attached on the surface of a specimen is subjected to repeated loads, the elastic stress
is measured by observing slip-bands in the foil resulting from repeated strain. Calibration studies with rotating-bending
tests at various temperatures between room temperature and 350°C are performed on round steel bars with nickel foil. The relation
between the threshold stress for the first appearance of slip-bands and the number of stress cycles is examined at varying
temperatures, which provides the calibration values of the nickel foil tested at varying temperatures. Assuming that the first
appearance of slip-bands is based on the linear cumulative damage law, the calibration values at varying temperatures are
calculated from those established by the calibration tests at several constant temperatures. It is found that the calculated
calibration values agree well with the results obtained by the calibration tests at varying temperatures and that the calculation
applying the linear cumulative damage law is a useful method to presume the calibration values at varying temperatures without
performing the experiment. 相似文献
884.
Ilyes Jedidi Zohra Ferhat‐Hamida Geneviève Delmas 《Journal of Polymer Science.Polymer Physics》2007,45(15):1932-1949
A linear Union Carbide PE (UC) has been analyzed by nonstandard calorimetry with a common DSC calorimeter and a Setaram C80 calorimeter. Nonstandard calorimetry entails using a low rate of heating (0.5–1 K/min), a small mass (0.5–1.5 mg), and an open cell (O‐cell) instead of the standard C‐cell. Events in O‐cells overlap less and occur with a faster kinetics than in C‐cells. PE crystals are nascent, solution‐grown (S‐grown), press‐grown (P‐grown), and strained by extrusion. In Part A, the traces show that the phase‐changes in the melt, previously observed in a C80 calorimeter (slow T‐ramp) and characterized by ΔHnetwork, can be observed with a common DSC in nonstandard conditions. In Part B, the difference between the C‐ and O‐cells and the changes in the main peak enthalpy (ΔHortho) are of interest. The main result is that, in O‐cells, the value of ΔHortho around Tortho, exceeds unambiguously in certain conditions ΔHortho found for perfect orthorhombic crystals. The main endotherm contains then another contribution, namely ΔHnetwork. Crystal reorganization during the slow T‐ramp is followed in the C‐ and O‐cells on S‐grown crystals. In O‐cells, lamellar thickening observed in the slow‐ramp is more extensive. The ease of phase‐change depends on the sample history. It is as follows: strained‐part extruded > nascent > S‐grown > P‐grown. Co‐operative chain motions are more hindered in the standard C‐cells than in the O‐cells. In Part C, lower values of m succeed in bringing phase‐changes in P‐grown (O‐cells) samples. The origin of the events is discussed: three processes are thought to contribute to the phase‐changes namely, melting of strained short‐range order, activation of vibrations in the CH2 groups, and fast decay of chain orientation which occurs simultaneously with melting. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1932–1949, 2007 相似文献
885.
罗世庄 《应用数学与计算数学学报》1997,11(1):65-70
本文首先给出了用当前基解和系数矩阵A的行(或列)增向量直接计算新基解及其检验数的一个简单公式,进而讨论了关于线性规划系数矩阵A的一行(列)向量变化的敏感性分析问题。给出了保持最优基不变时ΔA的变化范围。 相似文献
886.
887.
Professor J.F. Bell's empirical result regarding the rotation factor in the polar decomposition of the deformation gradient for the finite twist–extension of a thin-walled polycrystalline cylindrical metal tube is examined. The correct expression for the rotation is derived and used to show how Bell's result should be interpreted. Some implications for his incremental plasticity equations are also discussed. In particular, they are shown to satisfy appropriate invariance requirements when cast in terms of the variables actually measured by Bell in his experiments. Further consequences of his equations consistent with his data are also derived. Finally, it is shown that his theory furnishes a consistent constitutive statement about the response of isotropic solids provided that the Cauchy stress is constrained to be symmetric. 相似文献
888.
This paper introduces an elasto-plastic joint element characterised by strain hardening and softening in the analysis of dynamic
soil-structure interaction. The phenomena of separation and sliding on the contact surface between soil and structure can
be better simulated and the process can also be described. The interaction problems in a typical soil-structure system are
analyzed in terms of elasto-plastic joint element as well as elastic ones. The results show that the elasto-plastic joint
element is much better than the elastic one in modelling, especially in that the relative displacements accross the joint
element can be much greater than that of the elastic case. Separation and sliding are not only related to the coefficient
of friction and cohesion but also to their changes with plastic volumetric strain.
The project is supported by the Sciences Foundation of the Chinese Academy of Sciences and the Disaster Provention Institute
of Kyoto University (Japan). 相似文献
889.
In this paper, we introduce the two-dimensional continuous wavelet transform for the automated strain analysis of the moiré
interference fringe pattern. The Fourier transform method has been widely used for automated analysis of an optical interference
fringe pattern. However, this method is hardly applicable to the analysis of the fringe pattern, which includes large displacement
range or discontinuities. We show the advantages of the wavelet transform method by applying it to experimental results on
composite laminates. 相似文献
890.
粗粒土与结构接触面受载过程中的损伤 总被引:8,自引:0,他引:8
进行了粗粒上与结构接触面单调和循环加载试验,基于宏细观测量结果,扩展了损伤概念以描述该类接触面在受载过程中的物态演化,及由于物态演化导致的力学特性从初始状态到最终稳定状态的连续变化过程.揭示了接触面损伤的细观物理基础主要是接触面内土的颗牲破碎和剪切压密这两种物态演化;指出接触面的剪胀体应变可以划分为可逆性和不可逆性剪胀体应变两部分,其中不可逆性剪胀体应变可作为接触面损伤发展的宏观量度,因此其归一化形式可作为一种损伤因子的定义;提出了建立粗粒土与结构接触面一种损伤本构关系的基本思路. 相似文献