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柔弹性结构空间形态的非线性分析 总被引:2,自引:0,他引:2
计算力学领域柔软弹性结构的非线性分析是特别复杂的课题,更加困难与令人易于受挫的研究方向就是柔软弹性结构在各种复杂外力作用下的成形分析(Form Finding)或者平衡构形曲线的寻找,迄今为止的研究者大都局限于周边固定约束下求解柔软弹性结构的平衡曲线,因此其计算方法不具备广泛适用性,本文提出的动边界支座位移非线性迭代法成功地解决了这一问题,在工程上具有重要的应用价值。 相似文献
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借助Dirac广义函数,本文讨论了包含集中力在内的外力系作用下连续体的虚功方程与平衡方程及应力边界条件的等价性问题,证明在有限元计算中集中力的等效节点力可以从单元的虚功方程自然得到. 相似文献
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事件空间中非完整有势系统的参数方程 总被引:3,自引:0,他引:3
本文首先在事件空间中建立非完整有势系统的广义方程,然后给出此空间中表示Nielsen算子和Euler算子之间关系的两个定理,最后由这些定理得到广义Nielsen方程。 相似文献
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基于过去开展稀薄自由分子流到连续流气体运动论统一算法框架,采用转动惯量描述气体分子自旋运动,确立含转动非平衡效应各流域统一玻尔兹曼模型方程.基于转动能量对分布函数守恒积分,得到计及转动非平衡效应气体分子速度分布函数方程组,使用离散速度坐标法对分布函数方程所依赖速度空间离散降维;应用拓展计算流体力学有限差分方法,构造直接求解分子速度分布函数的气体动理论数值格式;基于物面质量流量通量守恒与能量平衡关系,发展计及转动非平衡气体动理论边界条件数学模型及数值处理方法,提出模拟各流域转动非平衡效应玻尔兹曼模型方程统一算法.通过高、低不同马赫数1:5~25氮气激波结构与自由分子流到连续流全飞行流域不同克努森数(9×10-4~10)Ramp制动器、圆球、尖双锥飞行器、飞船返回舱外形体再入跨流域绕流模拟研究,将计算结果与有关实验数据、稀薄流DSMC模拟值等结果对比分析,验证统一算法模拟自由分子流到连续流再入过程高超声速绕流问题的可靠性与精度. 相似文献
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一种求解有限元问题结点平衡方程的快速方法 总被引:1,自引:0,他引:1
目前随着工程实际问题复杂程度的增加及分析的要求,特别是材料非线性分析的引入,尽管计算机的运算速度、内存、外存容量等不断提高,但并不能完全满足大规模计算的需要,更快、更节省存贮空间的算法一直是有限元法分析过程中的一项核心技术要求。本文针对一些结点及单元均规律化地排列的有限元问题,提出可以透过其相邻结点的关系记录结点平衡方程中系数矩阵的非零元素,无需再像等带宽存贮那样去记录带宽内大量的零元素。此方法可以大大地减少系数矩阵元素的存贮量,从而可以提高计算机读取数据的速度及改善利用迭代法求解的效率。 相似文献
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转动Timoshenko梁的动力学方程及频率分析 总被引:5,自引:0,他引:5
本文以转动规范理论为基础,导出转动Timoshenko梁的精确动力学方程,并在梁作匀速转动的情况下讨论剪切效应、转动惯量、离心力的纵向分量等因素对梁固有频率的影响 相似文献
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实际工程中,拉索在索撑节点处滑移十分普遍。考虑滑移的影响,索撑节点不能简单地用铰接模拟。现有的拉索滑移分析方法往往需要迭代,计算过程复杂且收敛性无法保证。本文提出一种拉索滑移分析新方法——滑动元法,以预应力鱼腹梁为例进行理论推导,介绍了滑动元法的基本原理和计算步骤。结合有限元软件,利用滑动元法对算例进行计算分析,结果表明,滑动元法计算快速无需迭代,可以较为准确地分析拉索滑移。 相似文献
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Solutions of the integral equations for shearing stresses in two-material curved beams 总被引:1,自引:0,他引:1
Yu Aimin 《Mechanics Research Communications》2004,31(2):137-146
In the same way as shearing stresses for curved beams made of one material, the problem of evaluating the shearing stresses of composite curved beams is also reduced to one of solving the integral equations. Solving directly two integral equations can derive the formulae of shearing stresses, which satisfy not only the equilibrium equations but also the static boundary conditions on the boundary surfaces of the beams. The present analysis will be used to investigate the shearing stresses of a cantilevered curved beam made of two materials, which is loaded by a concentrated force at its free end. The comparison between the numerical results of shearing stresses obtained using the equations developed in this paper and a three-dimensional finite element analysis shows excellent agreement. 相似文献
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Test method for measuring strength of a curved sandwich beam 总被引:1,自引:0,他引:1
A fixture for testing curved sandwich beams in flexure was designed and evaluated. The test specimen is a continuous sandwich
beam consisting of a central circular 90° region connected by two straight legs. The fixture was designed according to the
four-point flexure principle to produce a pure bending moment in the curved region. The validity of the test fixture in producing
the desired loading was examined by fitting a curved aluminum bar of similar bending stiffness as the sandwich beams considered.
Strain gage readings were successfully compared to predictions from curved homogeneous beam theory. In addition, the deflection
of the beam at the loading points was analyzed using straight and curved beam theory for the various sections of the beam,
and predictions were compared to measured load-displacement response. Good agreement was achieved between experimental and
analytical results lending confidence to the test principle. Curved sandwich beams consisting of glass/polyester face sheets
over a PVC foam core were tested to failure and the loading response of the beams and their failure behavior are discussed.
It was found that the beams failed at the upper face/core interface due to radial tension stress. 相似文献
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In this study, a slightly curved Euler Bernoulli beam carrying a concentrated mass was handled. The beam was resting on an elastic foundation and simply supported at both ends. Effects of the concentrated mass on nonlin- ear vibrations were investigated. Sinusoidal and parabolic type functions were used as curvature functions. Equations of motion have cubic nonlinearities because of elongations during vibrations. Damping and harmonic excitation terms were added to the equations of motion. Method of mul- tiple scales, a perturbation technique, was used for solving integro-differential equation analytically. Natural frequen- cies were calculated exactly for different mass ratios, mass locations, curvature functions, and linear elastic foundation coefficients. Amplitude-phase modulation equations were found by considering primary resonance case. Effects of nonlinear terms on natural frequencies were calculated. Frequency-amplitude and frequency-response graphs were plotted. Finally effects of concentrated mass and chosen curvature function on nonlinear vibrations were investigated. 相似文献
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为模拟大柔度梁/绳索结构的变形和大范围运动,基于绝对节点坐标方法ANCF(Absolute nodal coordi-nate formulation)和HHT(Hilber-Hughes-Taylor)积分方法,建立了ANCF单元的隐式动力学迭代格式.得到了简洁的节点等效力向量,且进一步导出了切线刚度矩阵的全部公式,... 相似文献
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Solution of generalized coordinate for warping for naturally curved and twisted beams 总被引:1,自引:0,他引:1
A theoretical method for static analysis of naturally curved and twisted beams under complicated loads was presented, with special attention devoted to the solving process of governing equations which take into account the effects of torsion-related warping as well as transverse shear deformations. These governing equations, in special cases, can be readily solved and yield the solutions to the problem. The solutions can be used for the analysis of the beams, including the calculation of various internal forces, stresses, strains and displacements. The present theory will be used to investigate the stresses and displacements of a plane curved beam subjected to the action of horizontal and vertical distributed loads. The numerical results obtained by the present theory are found to be in very good agreement with the results of the FEM results. Besides, the present theory is not limited to the beams with a double symmetric cross-section, it can also be extended to those with arbitrary cross-sectional shape. 相似文献
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IntroductionFlexiblecableswithlargesagareakindofspecialengineeringstructures.Theyareusedinoverheadtransmissionlineswithhighvoltage,aerialcablesfortransport,largespanstructuresinbridgesandcivilengineering[1,2].Theywillmoveinlargerangeunderwind,loaddesigned… 相似文献