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1.
考虑面层横向剪切变形以及横向剪应力在面层和芯层粘结处连续,应用Hamilton原理建立了正交铺设复合材料面层夹层扁壳新的非线性精化理论。在静力问题情形,控制方程和边界条件化简为用四个基本未知函数表述。作为理论的应用,分析了简支边界条件下正交铺设复合材料面层夹层圆柱壳和夹层球壳的非线性弯曲,得到了其挠度响应和层间应力响应。 相似文献
2.
基于Von Karman板理论,应用三分区模型,建立了考虑横向剪切效应时具任意脱层的正交对称铺设轴对称层合圆板在径向压力荷载作用下的非线性运动微分方程。对未知变量在空间上采用Bessel函数,应用Galerkin法,得到无量纲的仅关于时间函数的运动微分方程,并应用谐波平衡法对此方程进行求解,算例中讨论了不同脱层半径、脱层深度对具脱层的正交对称铺设轴对称层合圆板非线性幅频响应的影响。 相似文献
3.
基于精确应力分析的广义六自由度板理论,应用变分原理和损伤力学中
的应变等效原理,考虑复合材料铺设层内和层间界面处的损伤效应,建立了具两种损伤模式
的复合材料层合板的三维非线性平衡微分方程,且运用有限差分法对考虑损伤简支层合梁板
的层间应力进行了求解. 相似文献
4.
针对复合材料夹层板的实际变形特征,基于Zig-Zag变形假定和Mindlin一阶剪切理论,建立了复合材料夹层板自由振动的有限元模型,在该模型中分别对上、下面板和芯体建立了三个独立坐标系,使三部分的转角独立,为具有厚夹芯和软夹芯的复合材料夹层板的动力分析提供了一种更为准确的有限元模型;在此基础上推导了相应的刚度阵和质量阵,并采用子空间迭代法求解。夹层板的固有频率。通过典型考题证明了本模型的有效性。文中最后还通过参数讨论,研究了具有不同长厚比的复合材料夹层板基频的变化规律。 相似文献
5.
复合材料面层夹层板中转动一致有效理论 总被引:3,自引:0,他引:3
采用分层位移模式,引入夹层板层间和表面剪应力协调条件,导出位移场的修正形式。根据能量误差一致原则,应用最小位能原理建立了复合材料层夹层板的基本方程和边界条件。 相似文献
6.
基于经典叠层板理论和几何大变形理论,将铝基蜂窝芯层等效为一正交异性层,等效弹性参数由修正后的Gibson公式得出,对四边固支蜂窝夹层板非线性动力学特性进行了分析。考虑横向阻尼的影响,建立了四边固支蜂窝夹层板受横向激振力作用的受迫振动微分方程,通过振型正交化将蜂窝夹层板受迫振动微分方程简化成双模态下的动力学控制方程,利用同伦分析方法对双模态下蜂窝夹层板的动力学控制方程进行研究,得到了1:3内共振下的幅频特性曲线,研究了不同结构尺寸对动力学特性的影响以及蜂窝夹层板作稳态运动时的稳定性问题。本文得到的结果为蜂窝夹层板的设计和实际应用提供了理论依据和数值参考。 相似文献
7.
本文概述了利用分析方法了解弹性层合板静态大挠度,后屈曲和非线性动态响应方面的进展.在对称层合板情况下不存在弯曲-拉伸耦合.应用了正交异性板或各向异性板的经典非线性理论,还提供了有关这些板的参考文献.简要评述了许多类型边界条件下一般层合板的非线性剪切变形理论和一般解法.在本综述中讨论的使复合材料板几何非线性行为复杂化的一些影响因素是:横向剪应力和正应力,转动惯量和面内惯量,面内初始边界力,几何缺陷,切口,以及非经典边界条件. 相似文献
8.
本文概述了利用分析方法了解弹性层合板静态大挠度,后屈曲和非线性动态响应方面的进展.在对称层合板情况下不存在弯曲-拉伸耦合.应用了正交异性板或各向异性板的经典非线性理论,还提供了有关这些板的参考文献.简要评述了许多类型边界条件下一般层合板的非线性剪切变形理论和一般解法.在本综述中讨论的使复合材料板几何非线性行为复杂化的一些影响因素是:横向剪应力和正应力,转动惯量和面内惯量,面内初始边界力,几何缺陷,切口,以及非经典边界条件. 相似文献
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10.
基于层合板壳理论,考虑反对称铺设层合板的拉弯耦合效应和后屈曲过程中的非线性几何变形,推导了由应力函数和挠度表示的复合材料层合板的后屈曲控制方程。引入无量纲参数对控制方程和边界条件进行无量纲化,以消除材料参数及几何尺寸对分析结果的影响。采用摄动法将无量纲的非线性控制方程及边界条件展开成一系列非齐次线性摄动方程组,分析各阶摄动方程的通解与特解的构造,并逐次求解,建立了反对称铺设复合材料层合板受单向均布压力作用的临界屈曲荷载及后屈曲平衡路径的理论解。进而运用ABAQUS软件对复合材料层合板在面内压缩载荷作用下的屈曲和后屈曲进行有限元分析,结果表明理论解与ABAQUS结果十分接近,验证了理论解的正确性。在此基础上进一步讨论了铺设角度、铺设层数和拉弯耦合效应等对层合板后屈曲性能的影响。研究发现层合板的屈曲载荷受铺设角度与层数的影响较为显著,而拉弯耦合效应使板的屈后强度大大降低。 相似文献
11.
The gradient model of stochastically inhomogeneous media is used to study the stress concentration around a circular hole
in a two-component elastic composite. The study is based on a general solution of the system of equilibrium equations expressed
in terms of harmonic functions and functions that satisfy the Helmholtz equation. This solution is used to solve problems
for an infinite plane with a circular hole under uniform and uniaxial tension. The results obtained are compared with the
solutions found using the theory of effective moduli, which is simpler
__________
Translated from Prikladnaya Mekhanika, Vol. 43, No. 12, pp. 41–53, December 2007. 相似文献
12.
Summary This paper outlines an analytical method for computing normal and shear stresses generated in a curved laminated beam under
bending loads. Each cross section is assumed to be symmetrical and loads are applied in the plane of symmetry. We build a
statically admissible stress field in order to plot normal and shear stress distributions.
Received 5 March 1997; accepted for publication 18 September 1997 相似文献
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14.
A general form for calculating residual stresses detected by using the holographic blind-hole method
A general form used for analyzing residual stresses measured using the holographic blind-hole method is introduced in this
paper. Adopting the general form presented, the residual stresses can be obtained using three relative displacements measured
from a single interference fringe pattern. Even for the case in which phase-shifting holographic interferometry is not employed,
interpolating calculations for determining the fringe orders are not needed, since the choice of data points becomes more
flexible when using this general form. Two experiments, the first one carried out by the authors and the second one published
previously, are used to illustrate the applicability and usefulness of this general form. Suggestions for the applications
of this general form are also established via the upper bound error estimations. 相似文献
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Rubber tube springs consist basically of cylindrical rubber tubes bonded on their inner and outer curved surfaces to rigid cylindrical tubes. They are widely used as flexible linkages, for example in vehicle suspensions. Rotation of one rigid tube with respect to the other about their common axis subjects the rubber tube to azimuthal shear. Displacement of one rigid tube with respect to the other along their common axis puts the rubber tube into axial shear. Using FEA, we have calculated the stresses set up in both cases, for a long rubber tube of a non-linearly elastic (neo-Hookean) material. The results are compared for the two modes of deformation, and with analytical predictions where available. For a long tube the shear stresses are substantially independent of the end conditions, but the normal stresses are strongly affected, as found previously for sheared rectangular blocks [A.N. Gent, J.B. Suh, S.G. Kelly III, Mechanics of rubber shear springs, Int. J. Nonlinear Mech. 42 (2007) 241-249]. If the end surfaces are stress-free, unexpectedly large normal stresses are generated, even in azimuthal shear. These high tensile stresses are attributed to restraints at the inner and outer cylindrical boundaries that compensate for the absence of stresses on the end surfaces that would be needed to maintain a simple shear deformation. Thus, the boundary conditions affect the stresses everywhere (in contrast to an “end effect” that would diminish away from the ends). Small departures from complete incompressibility are found to lower the internal stresses markedly, and even cause the sign of the stresses to be reversed. 相似文献
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18.
Mataz Alcoutlabi S. G. Baek J. J. Magda Xiangfu Shi S. A. Hutcheson G. B. McKenna 《Rheologica Acta》2009,48(2):191-200
A novel pressure sensor plate (normal stress sensor (NSS) from RheoSense, Inc.) was adapted to an Advanced Rheometrics Expansion
System rheometer in order to measure the radial pressure profile for a standard viscoelastic fluid, a poly(isobutylene) solution,
during cone–plate and parallel-plate shearing flows at room temperature. We observed in our previous experimental work that
use of the NSS in cone-and-plate shearing flow is suitable for determining the first and second normal stress differences
N
1 and N
2 of various complex fluids. This is true, in part, because the uniformity of the shear rate at small cone angles ensures the
existence of a simple linear relationship between the pressure [i.e., the vertical diagonal component of the total stress
tensor (Π22)] and the logarithm of the radial position r (Christiansen and coworkers, Magda et al.). However, both normal stress differences can also be calculated from the radial
pressure distribution measured in parallel-plate torsional flows. This approach has rarely been attempted, perhaps because
of the additional complication that the shear rate value increases linearly with radial position. In this work, three different
methods are used to investigate N
1 and N
2 as a function of shear rate in steady shear flow. These methods are: (1) pressure distribution cone–plate (PDCP) method,
(2) pressure distribution parallel-plate (PDPP) method, and (3) total force cone–plate parallel-plate (TFCPPP) method. Good
agreement was obtained between N
1 and N
2 values obtained from the PDCP and PDPP methods. However, the measured N
1 values were 10–15% below the certified values for the standard poly(isobutylene) solution at higher shear rates. The TFCPPP
method yielded N
1 values that were in better agreement with the certified values but gave positive N
2 values at most shear rates, in striking disagreement with published results for the standard poly(isobutylene) solution.
相似文献
J. J. MagdaEmail: |
19.
本文给出双材料板条结构的Suhir界面应力微分方程一般解,进而求解了温度沿板厚呈线性分布时因异材失配引起的界面剪应力和剥离应力,此解包含了均匀升温情况下的Suhir解。 相似文献
20.
S. I. Gerasimov 《Journal of Applied Mechanics and Technical Physics》2004,45(3):453-456
The issues of size and shape stability are especially important in modern high technologies, in particular, in the compact disk technology. Stability in this case is substantially affected by residual stresses that occur in disks because of the imperfection of their production process. The objective of the present study was to develop a simple optical method to estimate the stress state of compact disks. 相似文献