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1.
一般常用薄板单元分析薄壳内力,但由于内部边界联接斜率的不连续性而影响到求解精度。本文首先从薄壳的基本理论着手,用张量分析法建立了薄壳的势能原理和混杂变分原理。其次,对任意形状的薄壳,提出了采用混杂模型进行三角形单元的构式方法。最后,以螺旋曲面薄壳为例,导出了性质矩阵的形式。 相似文献
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矩形智能板弯曲形状的主动控制 总被引:4,自引:0,他引:4
研究具有离散分布压电控制器的矩形智能板,在外加电场作用下的弯曲形状与压电元件外加控制电压之间的关系,建立了对智能矩形板的弯曲形状进行主动控制的方法,得到各离散分布压电元件控制电压的解析解,并给出了算例 相似文献
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基于神经网络的结构变形估计和形状控制 总被引:6,自引:0,他引:6
准确的变形估计是智能结构形状控制的前提。本文基于人工神经网络(ANN)方法设计了智能桁架结构的变形估计器和形状控制器,根据结构系统有限数目的测量值可以估计结构变形并用于形状控制。该方法同时适于处理结构非线性问题。算例表明方法的可行性与有效性。 相似文献
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本文对旋转薄壳的位移、应力问题,提出了一种有效的曲线单元,可以计算曲率、壁厚及斜度有突变的各种形状的旋转薄壳。对非轴对称载荷问题,在圆周方向采用Fourier级数展开,是半解析的有限元法。 相似文献
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任意形状薄壳的弹性稳定性方程 总被引:2,自引:0,他引:2
本文用张量导出了任意形状薄壳的统一的弹性稳定性方程组,并且在正交曲线坐标系下化成了以张量的物理分量表示的方程,进而可以将正圆锥壳、球壳、圆柱壳、椭球壳、圆板、矩形板等形状的壳和板作为特例来研究。 相似文献
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蒸压釜是硅酸盐建材厂的关键设备.当按国外类似产品进行设计时,由于缺少强度计算文件而不能投产.我们受委托对现有引进结构进行强度计算和应力测试.这类蒸压釜是薄壳-实体组合式的压力容器(图1),结构的应力分析方法国内外尚未公开发表.由于结构形状复杂,经典的薄壳理论 ... 相似文献
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研究了磁场环境中受机械载荷作用的导电圆柱薄壳的热磁弹性问题.首先,根据电动力学方程和广义Ohm定律,得到了导电薄壳电流密度的分布,考虑到Joule热效应及热平衡方程,得到了导电薄壳的温度分布.其次,通过几何方程、物理方程、运动方程和电动力学方程导出了导电薄壳在机械场、电磁场以及温度场作用下的基本方程.最后,采用差分法及准线性化方法,得到了可以应用离散正交法求解的准线性微分方程组.对于导电圆柱薄壳,得到了Lorentz力表达式,并且推导了温度场积分特征值.讨论了导电圆柱薄壳应力、温度及变形随外加电磁参量的变化规律,并通过实例证实了可以通过改变电、磁、力场的参数来实现对薄壳的应力、应变、温度的控制. 相似文献
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含压电材料智能结构动态特性的研究 总被引:15,自引:1,他引:14
本文推导了含压电材料智能结构有限元动力方程,讨论了智能结构系统的动态特性,得到了模态形状和相应的模态电压以及考察了具有分布的压电传感器和执行器的四边简支方板的各阶固有频率随以馈增益的变化规律,这些结果将在智能结构控制的优化设计中起到了很大的作用。 相似文献
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考虑碳纳米管复合材料作为功能梯度材料的不均匀性,基于连续介质理论以及哈密尔顿变分原理,建立了功能梯度碳纳米管增强复合材料开口圆锥薄壳结构的非线性运动偏微分控制方程,然后利用Galerkin法,将非线性偏微分控制方程转化为常微分控制方程,进而采用谐波平衡法求解了开口圆锥壳的非线性自由振动问题,并探讨了圆锥薄壳几何参数、碳纳米管参数对结构非线性自由振动的影响.数值研究表明结构的无量纲非线性自由振动频率与线性自由振动频率的比值随圆锥薄壳长厚比的增大而变小、并随圆锥角的增大而变大. 相似文献
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An Exact Analysis for Free Vibration of a Composite Shell Structure-Hermetic Capsule 总被引:2,自引:0,他引:2
尚新春 《应用数学和力学(英文版)》2001,22(9):1035-1045
IntroductionCompositestructuresconsistingofshellsofrevolutionhavewideapplicationsinvariousengineeringfieldssuchasaerospace ,chemical,civil,mechanical,marineengineering .Duetothemathematicalcomplexityofshellequationsandthedifficultytomatchconditionsofthe… 相似文献
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G. S. Leizerovich S. V. Seregin 《Journal of Applied Mechanics and Technical Physics》2016,57(5):841-846
The effect of a small added mass on the frequency and shape of free vibrations of a thin shell is studied using shallow shell theory. The proposed mathematical model assumes that mass asymmetry even in a linear formulation leads to coupled radial flexural vibrations. The interaction of shape-generating waves is studied using modal equations obtained by the Bubnov–Galerkin method. Splitting of the flexural frequency spectrum is found, which is caused not only by the added mass but also by the wave-formation parameters of the shell. The ranges of the relative lengths and shell thicknesses are determined in which the interaction of flexural and radial vibrations can be neglected. 相似文献
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A plane acoustic wave travelling through an infinite inviscid fluid is scattered by an empty thin shell. A simple approximate but explicit formula is proposed to describe the behaviour of the acoustic pressure scattered by the shell, at an observation point situated in the far field, for backscattering. Only the contributions to the scattered field of specularly reflected, refracted and re-radiated wave are taken into account. The domain of validity of the proposed approximation is given. An example of the frequency dependent calculation is presented for the case of an Armco iron shell with elliptical cross shape immersed in water. 相似文献
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George V. Palassopoulos 《基于设计的结构力学与机械力学》2013,41(3):177-193
ABSTRACT A simple general method for the evaluation of the effect of shape imperfections on the buckling of thin shells is briefly presented. This method is applied to the axially compressed thin cylindrical shell resulting in an efficient numerical procedure for the computation of its buckling strength. The procedure is applicable to any sufficiently smooth imperfection pattern and has given results in good agreement with the available experimental data. 相似文献
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《International Journal of Solids and Structures》2007,44(5):1593-1607
This paper addresses a method for shape design sensitivity analysis of a buckling load in a continuous elastic body. The sensitivity formula for critical load is analytically derived and expressed in terms of shape variation, based on the continuum formulation of the stability problem. Though the buckling problem is more efficiently solved by structural elements such as a beam and shell, elastic solids have been chosen for the buckling analysis in this paper because solid elements can generally be used for any kind of structure whether it is thick or thin. The initial stress and buckling analysis is carried out by the commercial analysis code ANSYS. Sensitivity is then computed by using the mathematical package MATLAB with the results of ANSYS. Several problems including straight and curved beams under compressive load, ring under pressure load, thin-walled section and bottle shaped column are chosen in order to illustrate the efficiency of the presented method. 相似文献
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无单元法分析薄板自由振动问题 总被引:8,自引:0,他引:8
提出了分析四边简支和四边固定薄板自由振动问题的无单元法,推导了无单元法的插值函数,从变分原理出发导出薄板自由振动的质量矩阵和刚度矩阵,编制了相应的计算程序,通过计算实例与其它方法的结果进行比较.数值结果表明无单元法具有一系列优点。 相似文献
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We use the equations of nonlinear theory of shallow shells to solve the problem of stability of thin elastic isotropic cylindrical
shells, with small initial shape imperfections, that are under the action of external uniform pressure. The problem solution
is constructed by the Rayleigh-Ritz method with the approximation of the shell midsurface displacement by double functional
sums in trigonometric and beam functions. The system of nonlinear algebraic equations is solved by using the methods of continuation
with respect to a close-to-best parameter. For the initial imperfections of the shells, we use their normalized deflections
from the limit points of overcritical branches of the loading trajectories. We consider various cases of the shell fixation
and support under loading by lateral and hydrostatic uniform pressure. We also construct the range of values of the critical
pressure, which, with the maximal deviation of the shell shape from the cylindrical shape up to 30%, covers practically all
known experimental data. 相似文献
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《International Journal of Solids and Structures》2006,43(3-4):642-657
A supercavitating torpedo is a complex high speed undersea weapon that is exposed to extreme operating conditions due to the weapon’s speed. To successfully design a torpedo that can survive in this environment, it is necessary to consider the torpedo shell as a critical component. The shell of a supercavitating torpedo must be designed to survive extreme loading conditions (depth pressure and thrust loading), meet frequency constraints, and fit inside the cavity generated by the cavitator. In this research, an algorithm to determine the optimal configuration of the torpedo is presented. This method formulates an optimization problem that determines the general shape of the torpedo in order to satisfy the required performance criteria. Simultaneously, a method to determine the optimal stiffener configuration in the torpedo structure is also presented. A torpedo configuration for a desired speed is obtained and the details of the process are thoroughly discussed. 相似文献