共查询到20条相似文献,搜索用时 812 毫秒
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基于当流活塞理论的气动弹性计算方法研究 总被引:3,自引:0,他引:3
发展了一种高效、高精度的超音速、高超音速非定常气动力计算方法--基于定常CFD技术的当地流活塞理论.运用当地流活塞理论计算非定常气动力,耦合结构运动方程,实现超音速、高超音速气动弹性的时域模拟.运用这种方法计算了一系列非定常气动力算例和颤振算例,并和原始活塞理论、非定常Euler方程结果作了比较.由于局部地使用活塞理论假设,这种方法大大地克服了原始活塞理论对飞行马赫数、翼型厚度和飞行迎角的限制.与非定常Euler方程方法相比,当地流活塞理论的效率很高. 相似文献
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在采矿中崩落和诱导崩落的经典计算方法是采用应力集中和梁板理论。本文所建议的非经典理论计算方法改善了目前的计算结果。一、前言在采矿中,破坏岩石和防止岩石破坏,都同 ... 相似文献
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混合高斯粒子滤波在组合导航中应用的计算量分析 总被引:2,自引:2,他引:0
针对组合导航中出现的线性非线性混合滤波实现过程中的计算量问题,给出了一种混合高斯粒子滤波改进算法的计算量分析方法。根据该滤波算法特点,分析并总结了一种理论获取粒子滤波计算量的方法,据此定量的分析了该算法的计算量。并以SINS/GPS组合导航系统为例,具体分析了混合高斯粒子滤波算法计算量问题。仿真结果验证了该计算量理论分析方法的有效性。该方法同样可以推广到一般粒子滤波和其它非线性滤波算法中,能在理论上解决组合导航系统中非线性滤波计算量及滤波时间的计算仿真问题。 相似文献
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基于桁架结构稳定性计算的经典理论,分析了利用特征值理论开展桁架结构屈曲分析的计算方法,以及利用欧拉临界载荷屈曲理论,采取杆件撤除的静力求解确定桁架结构稳定临界载荷的计算方法. 通过理论研究和相关算例分析,论证了利用特征值理论和临界载荷屈曲理论相结合的方法,判断小变形桁架结构的失稳模态,求解桁架结构稳定临界载荷的确定性. 相似文献
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基于厚板理论分析深水域中弹性浮板的水波响应 总被引:1,自引:1,他引:0
基于线性水波理论和Mindlin厚板动力学理论,采用Wiener-Hopf 方法,研究了不同水深水面上弹性浮板在不同入射波数水波作用下的动力学响应问题。首先推导了无限深水域中弹性浮板水波响应的解析解,并将本文分析计算结果与采用其他方法(经典薄板理论)得到的计算结果进行了对比和分析;其次,采用本文方法研究了大型浮板在三种入射波数的水波作用下动弯矩幅值的分布情况;最后,根据其他文献的方法计算了不同水深(有限水深)情况下浮板的动响应,并与本文的计算结果进行了对比分析。 相似文献
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单层平面索网幕墙结构的几何非线性问题研究 总被引:4,自引:0,他引:4
单层平面索网支承式玻璃幕墙结构是近年来在国内外应用较为广泛的一种新型幕墙结构形式,由于单层平面索网不具有负高斯曲面形式,结构在平面外方向的刚度偏柔,表现出较明显的几何非线性特征.本文采用连续化方法建立了单层平面索网结构考虑几何非线性影响的静力平衡方程和振动方程,得到了结构刚度的解析表达式,并采用谐波平衡法求得非线性频率的简化解析表达式,以此为基础研究了单层平面索网结构的静力非线性和动力非线性问题.研究结果表明:结构的非线性和结构的初始位置密切相关;结构的非线性频率主要取决于索的初始应变、结构振动幅值与跨度的比值,几何非线性对于结构动力性能的影响要小于对结构静力性能的影响;本文得到的结构在地震荷载和平均风荷载作用下的非线性振动方程和非线性频率为结构在地震荷载和脉动风荷载作用下动力响应的求解奠定了基础. 相似文献
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Based on the linear viscoelastic differential constitutive law and cable structural model, the coupled longitudinal-transverse
waves that propagate along a viscoelastic cable with small curvature is investigated. A mathematical model is presented that
describes the three-dimensional nonlinear response of a viscoelastic cable. An asymptotic form of this model is obtained for
the linear response of cables having small equilibrium curvature. The spectral relation governing the propagating waves is
derived using transform methods. The spectral relation is employed in deriving a Green's function that is then used to construct
solutions for in-plane response under distributed harmonic excitation. Analysis of forced response reveals the existence of
two types of periodic waves that propagate through the cable, one characterizing extension-comprehensive deformation and the
other characteristic transverse deformation.
Project supported by the National Natural Science Foundation of China (No. 59635140). 相似文献
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A design model is proposed to describe spatial cable-stayed systems with slipping cables. The basic variables of the displacement
method are selected. A system of nonlinear equilibrium equations is derived from the condition of minimum potential energy,
taking into account the large displacements of joints and the large deformations of cables. A method and formulas needed to
iteratively solve the system of nonlinear equations are presented. Individual consideration is given to a cable net with prescribed
tension. The computed results make it possible to fabricate and mark out cable rods and to assemble cable nets based on their
geometry alone, without the need for force measurement
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 5, pp. 79–87, May 2006. 相似文献
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Nonlinear transient response of stay cable with viscoelasticity damper in cable-stayed bridge 总被引:1,自引:0,他引:1
Taking the bending stiffness, static sag, and geometric non-linearity into consideration, the space nonlinear vibration partial differential equations were derived. The partical differential equations were discretized in space by finite center difference approximation, then the nonlinear ordinal differential equations were obtained. A hybrid method involving the combination of the Newmark method and the pseudo-force strategy was proposed to analyze the nonlinear transient response of the inclined cable-dampers system subjected to arbitrary dynamic loading. As an example, two typical stay cables were calculated by the present method. The results reveal both the validity and the deficiency of the viscoelasticity damper for vibration control of stay cables. The efficiency and accuracy of the proposed method is also verified by comparing the results with those obtained by using Runge-Kutta direct integration technique. A new time history analysis method is provided for the research on the stay cable vibration control. 相似文献
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I. Vassilopoulou C. J. Gantes 《Archive of Applied Mechanics (Ingenieur Archiv)》2012,82(10-11):1689-1703
The dynamic behavior of the simplest possible cable net is studied in this paper, consisting of two crossing cables in perpendicular vertical planes, having the same span and opposite sags. A concentrated mass is attached at the central node, and only the vertical translational degree of freedom is assumed as active. First, the static behavior is explored up to the load level that causes tensile cable failure. Then, the dynamic response is investigated for different resonant conditions and is found to give significantly larger amplitudes with respect to the static ones, even for loading frequencies away from the eigenfrequency of the system. In order to derive analytical solutions, the equation of motion is simplified and the cable net is proved to be a Duffing oscillator. For the simplified problem, the occurrence of nonlinear phenomena is verified analytically, such as bending of the response curve, jump phenomena, instability regions, dependence on the initial conditions, and superharmonic and subharmonic resonances. These phenomena are also detected by means of numerical analyses. A comparison between the exact model and the simplified one shows that the analytical solution of the Duffing equation describes the dynamic behavior of the cable net with satisfactory accuracy. 相似文献
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《Journal of Fluids and Structures》2007,23(7):1077-1092
A theory of free linear vibrations of arbitrarily sagged inclined cables in a viscous fluid is presented in the framework of the heavy fluid loading concept. The static equilibrium shape of the cable is found by using the model of inextensible catenary and the validity ranges of this approximation are assessed. The dynamics of the viscous fluid is described by the linearised Navier–Stokes equations and their solution is pursued analytically by formulating the fluid field variables via potential functions. The vibration problem of a submerged cable is solved by Galerkin's method and the modal added mass and modal viscous damping coefficients are calculated. As a prerequisite for this analysis, the free vibrations of a cable in vacuum are addressed and a very good agreement with known results is observed. The physical interpretation of the dependence of modal added mass and modal damping coefficients on the ‘design variables’ for a fluid-loaded cable is given and the possible extensions of the suggested theory to capture weakly nonlinear effects are highlighted. 相似文献
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This paper is first of the two papers dealing with analytical investigation of resonant multi-modal dynamics due to 2:1 internal
resonances in the finite-amplitude free vibrations of horizontal/inclined cables. Part I deals with theoretical formulation
and validation of the general cable model. Approximate nonlinear partial differential equations of 3-D coupled motion of small
sagged cables – which account for both spatio-temporal variation of nonlinear dynamic tension and system asymmetry due to
inclined sagged configurations – are presented. A multi-dimensional Galerkin expansion of the solution of nonplanar/planar
motion is performed, yielding a complete set of system quadratic/cubic coefficients. With the aim of parametrically studying
the behavior of horizontal/inclined cables in Part II [25], a second-order asymptotic analysis under planar 2:1 resonance
is accomplished by the method of multiple scales. On accounting for higher-order effects of quadratic/cubic nonlinearities,
approximate closed-form solutions of nonlinear amplitudes, frequencies and dynamic configurations of resonant nonlinear normal
modes reveal the dependence of cable response on resonant/nonresonant modal contributions. Depending on simplifying kinematic
modeling and assigned system parameters, approximate horizontal/inclined cable models are thoroughly validated by numerically
evaluating statics and non-planar/planar linear/non-linear dynamics against those of the exact model. Moreover, the modal
coupling role and contribution of system longitudinal dynamics are discussed for horizontal cables, showing some meaningful
effects due to kinematic condensation. 相似文献
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Marco Lepidi Vincenzo Gattulli Fabrizio Vestroni 《International Journal of Solids and Structures》2007,44(25-26):8194-8212
In cable-stayed structures cables are subjected to potential damage, mainly due to fatigue and galvanic corrosion. The paper presents an analysis of damage effects on the statics and dynamics of suspended cables. An elastic continuous monodimensional model for damaged cables, including geometric nonlinearities, is formulated for the purpose. The damage is described as a diffused reduction of the cable axial stiffness, and defined through its intensity, extent and position. Exact solutions of the equations governing the cable static equilibrium under self-weight are achieved, and the significance of the tension loss and sag augmentation resulting from damage are investigated under variation of practically significant parameters. The system spectral properties characterizing the free undamped dynamics are obtained in a closed-form fashion for shallow cables within the low frequency range. The sensitivity of the frequencies to the intensity and extent of damage is discussed, outlining two damage effects, which alternatively stiffen or soften the cable modes, whose respective static and geometric origin is recognized. Finally, the symmetry-breaking induced by damage on the static profile is verified to destroy the crossing phenomenon (crossover) characterizing the frequency loci of undamaged cables, which degenerates into a narrow frequency veering phenomenon. 相似文献