共查询到20条相似文献，搜索用时 250 毫秒
1.
We studied the problem of bifurcation and chaos in a 4-side fixed rectangular thin plate in electromagnetic and mechanical fields. Based on the basic nonlinear electro-magneto-elastic motion equations for a rectangular thin plate and the expressions of electromagnetic forces, the vibration equations are derived for the mechanical loading in a steady transverse magnetic field. Using the Melnikov function method, the criteria are obtained for chaos motion to exist as demonstrated by the Smale horseshoe mapping. The vibration equations are solved numerically by a fourth-order Runge-Kutta method. Its bifurcation diagram, Lyapunov exponent diagram, displacement wave diagram, phase diagram and Poincare section diagram are obtained. 相似文献
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给出了横向磁场作用下矩形薄板的磁弹性振动方程,针对一边固定、三边简支的矩形薄板,通过位移模态展开,并利用Galerkin法得到两自由度内共振非线性振动微分方程组。算例分析中,利用数值方法得到了系统内共振时两阶模态的时间历程响应图和相平面图,并分别讨论了系统初值及磁场强度对系统振动的影响。结果表明,系统呈现明显的非线性内共振特征。 相似文献
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基于麦克斯威尔方程,给出导电薄板的非线性磁弹性振动方程,以及磁场环境下的电动力学方程和电磁力表达式。在此基础上,应用伽辽金法导出相应的非线性振动微分方程组,研究横向恒定磁场中周期载荷作用下梁式薄板的稳定性问题。根据李雅普诺夫近似稳定性理论,对稳态解的稳定性进行分析,得到稳定性的判定条件。通过对算例特征值的求解对振动的稳定性进行分析。 相似文献
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刘成武郭小斌 《福建工程学院学报》2020,(4):375-380
利用有限元法与边界元法结合对薄板进行振动声辐射特性分析,研究了薄板结构在简谐力作用下表面声压分布状况,分析了不同边界条件、材料以及加筋形式等因素对薄板结构振动声辐射特性的影响,并对简支矩形薄板厚度进行了优化。研究表明,边界约束的增加会导致薄板刚度变大,进而导致薄板辐射声功率与辐射效率随之改变?不同材料对结构的辐射声功率均有影响,而对辐射效率影响很小?加筋对薄板声辐射特性影响显著,十字型加筋形式减震降噪效果最好?对薄板厚度进行优化,优化后薄板辐射声功率级下降了4.29dB。 相似文献
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郑珂 《陕西教育学院学报》2009,25(4):79-83
利用薄板的弯曲振动理论推导出了不同边界条件下,改进弯振圆板在不同振动模式下的波节圆半径。利用瑞丽积分求解出了具有一个环带辐射区的弯振板的通用声压及指向性表达式,编制程序并绘出了弯振板轴对称弯曲振动时辐射声压的远场指向性图,同时对不同边界的声场指向性图作了对比。结果表明自由边界的改进弯振圆板辐射声场指向性最强。本文为此类弯振板的理论设计及实际应用提供了一定的理论依据。 相似文献
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Xu Xu Shan Feng 《上海大学学报(英文版)》1998,2(2):112-116
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With the terms of the exact series solution taken as trial functions, the method of point collocation was used to calculate the large deflection of a circular plate. The axisymmetrical bending formulae were developed for the calculation of a circular plate subjected to polynomial distributed loads, a concentrated load at the center, uniform radial forces and moments along the edge or their combinations. The support may be elastic. The buckling load was calculated. Under action of uniformly distributed load, central load or their compound load, solutions were compared with those obtained by other methods, Buckling beyond critical thrust was compared with that calculated by the power series method. The method presented in this paper has advantages of wide convergent range, high precision and short computing time. Moreover, the computing time is nearly independent of the complexity of the loads. 相似文献
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对薄圆盘的弯曲振动和辐射声场的特性进行了研究,推导出了三种边界条件下圆盘辐射声场指向性的数值表达式,编制程序并研究其声辐射特性。结果表明,相同尺寸不同边界条件下圆盘指向性的尖锐程度不同,固定边界条件下圆盘辐射声场指向性最佳,自由边界条件下较差,并且随着圆盘模式和几何尺寸的增加各边界条件下圆盘的指向性均逐渐变差。 相似文献
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论述了一种抑制载重绳索参数激励横向振动的简便方法. 假设绳索底端的质量受到一个垂直简谐激励并忽略载重绳索高阶振型的影响, 载重绳索的运动方程可以用一个带有立方非线性项的Mathieu方程来描述. 根据Mathieu方程的有关理论, 在载重绳索系统中, 当索端质量垂直振动的频率接近绳索横向振动固有频率2倍时, 一旦索端质量垂直振动的幅度超过某个临界数值时, 绳索将产生参数共振. 为了避免这种现象, 建议在索端质量上加装一个减振器以削减索端质量的垂直振动, 进而抑制绳索的横向振动. 实验验证了该减振方案的有效性. 相似文献
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文章研究双环掺铒光纤激光器激光混沌偏振产生及其偏振同步思想方法,用偏振器控制产生混沌激光偏振到任意方向,用克尔盒调制控制产生混沌激光旋传偏振态,用四分之一波片进一步控制分解产生新的混沌激光偏振态.调制控制双环掺铒光纤发射系统一路上的克尔盒使输出混沌激光分别产生左旋和右旋圆偏振态,并可动态控制产生混沌圆偏振光;设置接收系统四分之一波片进一步使混沌圆偏振激光控制变化为水平和垂直线偏振态,另一路偏振控制器控制产生水平和垂直偏振光,驱动二个接收子系统且实现和发射系统分别在水平和垂直偏振态上的混沌同步. 相似文献
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Winkler地基上四边自由矩形薄板的1/3次亚谐共振与混沌分析 总被引：1，自引：0，他引：1
研究Winkler地基上四边自由矩形薄板的复杂运动,按照弹性力学理论建立Winkler地基上四边自由受简谐激励作用矩形薄板的动力学方程;利用Galerkin方法将其转化为非线性振动方程;应用非线性振动的多尺度法求得了系统满足1/3次亚谐共振情况时的一次近似解,并进行数值计算;分析激励、调谐值、阻尼等对系统响应曲线的影响;应用Floquet理论分析了系统的稳定性问题;应用Melnikov方法得到了系统可能产生混沌运动的条件。 相似文献
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3D couette flow of dusty fluid with transpiration cooling 总被引：1，自引：0，他引：1
GOVINDARAJAN A RAMAMURTHY V SUNDARAMMAL K 《浙江大学学报(A卷英文版)》2007,8(2):313-322
INTRODUCTION Transpiration cooling is a very effective process to protect certain structural elements like combustion chamber walls, exhaust nozzles, or gas turbine blades in turbojet and rocket engines, from the influence of hot gases. In view of this, Eckert (1958) obtained an exact solution of the plane couette flow with transpi-ration cooling. The problem remained 2D due to the uniform injection and suction applied at the porous plates. Flow and heat transfer along a plane wall with… 相似文献
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A rectangular thin plate vibration model subjected to inplane stochastic excitation is simplified to a quasinonintegrable Hamiltonian system with two degrees of freedom. Subsequently a one-dimensional Ito? stochastic differential equation for the system is obtained by applying the stochastic averaging method for quasi-nonintegrable Hamiltonian systems. The conditional reliability function and conditional probability density are both gained by solving the backward Kolmogorov equation numerically. Finally, a stochastic optimal control model is proposed and solved. The numerical results show the effectiveness of this method. 相似文献
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李峰帜 《石家庄铁路职业技术学院学报》2013,12(2):8-13
重载铁路运输线中桥墩类型多为圆柱型、圆端型以及矩形板型,随着重载铁路运输干线列车轴重以及载运量的增加,给桥墩也带来了许多不利影响,如横向振幅过大、振动加剧等,严重影响了线路运营安全。以圆柱型和圆端型桥墩为研究对象,通过理论计算并结合朔黄铁路多座桥梁运营性能试验,对两种类型桥墩横向振动特性进行了系统研究。 相似文献
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刘成武 《福建工程学院学报》2012,(1):37-40
在ANSYS环境下,以对边简支的自由矩形板作为车身壁板的简化模型作为研究对象,讨论了在不同材料下、不同厚度下板的各阶固有频率的变化并进行加筋板和无加筋板的对比,对不同形式的加筋板结构布置形式进行分析和评价,从理论上指导了加筋板在车身壁板振动特性优化上的应用。结果表明,采用合理的材料、合理的加筋形式,对车身壁板的振动特性都有着很大的影响。 相似文献
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This paper is concerned with the free vibration analysis of open circular cylindrical shells with either the two straight edges or the two curved edges simply supported and the remaining two edges supported by arbitrary classical boundary conditions. Based on the Donnell-Mushtari-Vlasov thin shell theory, an analytical solution of the traveling wave form along the simply supported edges and the modal wave form along the remaining two edges is obtained. With such a unidirectional traveling wave form solution, the method of the reverberation-ray matrix is introduced to derive the equation of natural frequencies of the shell with different classical boundary conditions. The exact solutions for natural frequencies of the open circular cylindrical shell are obtained with the employment of a golden section search algorithm. The calculation results are compared with those obtained by the finite element method and the methods in the available literature. The influence of length, thickness, radius, included angle, and the boundary conditions of the open circular cylindrical shell on the natural frequencies is investigated. The exact calculation results can be used as benchmark values for researchers to check their numerical methods and for engineers to design structures with thin shell components. 相似文献
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本文首先建立了含横向裂纹弹性盘轴系统的动力学模型,然后利用Lagrange方程推导出了系统的动力学方程,接着采用假设模态法对变量进行离散,求出了系统振动频率与轴的转速、裂纹深度及裂纹位置的关系,并与有关文献进行了比较。 相似文献
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王树勇 《海南师范学院学报》2007,20(4):331-334
研究绕一端旋转的弹性梁产生的拉压与弯曲的复合振动，采用分离变量法，求出旋转梁在横向受两端固定铰链约束、纵向两端自由弯曲和拉压耦合振动的微分方程通解． 相似文献