壳板组合结构功率传递分析

壳板耦合是圆柱壳组合结构中最常见的连接方式。为了研究壳板组合结构的功率传递规律,利用有效点导纳分析周向均布激励下圆柱壳表面振动响应的分布规律,得出圆柱壳振动响应理论计算公式;通过给出圆周线导纳的定义及其表达式,计算带端板圆柱壳的振动响应均方值之比。理论计算结果表明:壳板振动响应均方值之比随频率的增高逐渐增大,但其值始终小于1。实验测量结果与理论计算吻合,其值围绕理论值上下波动,表征了理论计算公式和分析结果的正确性和合理性。     

薄壁液压管道声振耦合分析

薄壁液压管道中,由于液体中声场和管道结构中振动波场的相互耦合作用而使得液体中的声能量通过管道损失。为了分析圆柱形液压管中的这种能量损失机理,本文基于阻抗导纳法研究液压管的声振耦合现象。从声波波动方程和圆柱壳的结构动力学方程出发推导了薄壁液压管的声振耦合方程。推导圆柱壳结构动力学方程时考虑了横截面的变形,这一点不同于以往的液压管的研究。为了验证推导的基于阻抗导纳法的声振耦合控制方程,用有限元方法和推导的阻抗导纳法模型分别计算了充满液体的圆柱壳的声振耦合响应,结果吻合较好,证明了推导的方法的合理性。     

载流管道振动输入功率流的主动控制

研究基于主动力方式的充液圆柱壳结构输入振动功率流控制,分析了充液圆柱壳受激振动的响应,利用导纳函数求解结构响应.将构造结构总的输入功率流为二次型函数作为控制目标函数.利用哈密尔顿二次型最小值理论给出了最优控制力前馈控制表达式.分析了重要参数对壳体结构振动功率流控制效果的影响.     

不同边界条件下旋转薄壁短圆柱壳的强迫振动响应计算

为计算不同边界条件下旋转薄壁短圆柱壳的强迫振动响应特性,在总结前人所提出的两端简支边界条件下旋转有限长圆柱壳自由振动和谐波激励响应计算方法基础上,基于梁函数法,在位移函数的轴向引入含有不同边界条件特征的模态函数,从而得以求解。基于Love壳体理论,利用Harnilton原理建立了旋转薄壁短圆柱壳的振动微分方程,并利用Galerkin法进行离散简化为常微分方程。以简谐激励为例给出了一种以广义坐标形式表示的响应求解方法,由此求解出不同边界约束的旋转薄壁短圆柱壳的响应问题。通过试验对所提出响应计算方法的正确性进行了验证。     

薄壁圆柱壳振动应力间接测量方法研究

为了进一步了解薄壁圆柱壳的振动特性,提出了一种间接测试薄壁圆柱壳振动应力的方法。首先利用谐响应分析方法计算获得了结构在不同基础激励幅度下的振动应力和响应;然后通过最小二乘法得到"振动应力-响应"关系曲线,建立了两者的数值表达式,明确了间接测试其振动应力的理论基础。最后通过实例对此方法进行了验证,结果表明此间接测试方法具有较好的测试精度。提出了薄壁圆柱壳振动应力间接测量的方法及流程,并对其中的关键环节,如Rayleigh阻尼的确定以及基于实验数据的有限元模型的修正方法进行了详细论述,可以为薄壁圆柱壳振动应力的测试问题提供一种新思路。     

工装约束下火箭舱段壳体的结构振动特性研究

将地面试验中卡环工装对舱段壳的影响转化为弹性边界条件下圆柱壳耦合结构的振动问题,通过卡环工装与圆柱壳接触建模计算得到工装作用于舱段壳的法向约束刚度,并采用增补函数的方法构建了工装约束边界条件下圆柱壳耦合结构的振动理论分析模型。结果表明：本研究模型能够反映卡环工装对于舱段壳振动特性的影响,理论计算结果与试验测试结果的变化趋势基本一致;在卡环工装的约束下,舱段壳的低频振动受到显著抑制,工装的约束刚度及其在舱段壳上的夹持位置对于舱段壳振动特性具有较大影响。     

篦齿对悬臂薄壁圆柱壳振动响应的影响研究

采用有限元方法和实验方法研究了篦齿结构对悬臂薄壁圆柱壳响应特性的影响。首先,在悬臂边界条件下,通过有限元法建立了带周向篦齿结构的三维薄壁圆柱壳模型,采用谐响应分析中的模态叠加法对受到单点谐波激振力时的响应行为进行了求解,得到了受迫响应的幅频特性曲线和悬臂端周向节点的响应特征,并通过试验测试对结果进行了验证,最后比较了带有不同的篦齿布置形式、篦齿高度和篦齿道数时薄壁圆柱壳构件的响应特性。分析结果表明,通过有限元方法和试验测试得到的悬臂薄壁圆柱壳的响应特征一致,在共振激励时的响应行为与圆柱壳结构的模态相关,由于悬臂边界条件和篦齿对整体结构刚度的作用,篦齿结构的布置形式、高度和道数对薄壁圆柱壳构件的响应特性均有较大影响。     

圆柱壳体基础隔振系统导纳功率流特性

针对圆柱壳体基础上动力装置隔振问题,建立复杂振源激励、多弹性支承、柔性圆柱壳体多维耦合传递矩阵力学模型。基于经典薄壳理论和模态叠加原理,同时计及奇偶模态响应,给出两端剪力薄膜支撑各向同性圆柱壳体的点导纳解析表达式,以导纳矩阵形式表征不同激励组分与速度响应的交叉耦合关系。考虑弹性支承的多维波动效应,运用子结构导纳法推导整体系统的功率流传递方程。研究表明:振源垂向、横向激励力与倾倒力矩诱发的隔振器纵向及弯曲谐振是中高频域系统功率流提高的主要原因;力矩激励对于柔性壳体基础功率流传输具有重要影响;壳体基础的径向弯曲振动在整个系统能量传递中占据支配地位,与其相关的弯曲机械波是主要结构声源。所用建模分析方法具有模块化延拓性,旨在为系统结构参数优化及后续的主被动一体化控制策略确立理论依据。     

不同介质中圆柱壳体的低阶模态声辐射特性研究

基于Flugge壳体理论,利用柱坐标系下Green函数和模态展开法,推导了两端简支有限长圆柱壳的声振耦合方程,求解了圆柱壳的辐射声功率和表面均方振速,对比研究了圆柱壳在不同流体中各周向阶数对径向均方振速和辐射声功率的贡献。结果表明,有限长圆柱壳受简谐径向点力激励,空气中,较大周向阶数的振动模态对声功率产生一定量的贡献;当圆柱壳浸入水中时,低频范围内前几阶周向阶数的振动模态对水下圆柱壳辐射声功率的贡献最大。     

圆柱壳自由振动的有限元分析

以位移模型为基础,用有限元中的分离变量法的理论,求解了圆柱壳自由振动的固有频率,计算结果与壳体解析解相一致。本方法具有节省内存,减少计算工作量的优点,是利用微机解决复杂结构计算的有效途径。     

Exact solutions for vibration of cylindrical shells with intermediate ring supports

This paper presents new exact solutions for vibration of thin circular cylindrical shells with intermediate ring supports, based on the Goldenveizer–Novozhilov shell theory (Theory of thin shells; The theory of thin elastic shells). An analytical method is proposed to study the vibration behaviour of the ring supported cylindrical shells. In the proposed method, the state-space technique is employed to derive the homogenous differential equation system for a shell segment and a domain decomposition approach is developed to cater for the continuity requirements between shell segments. Exact frequency parameters are presented in tables and design charts for circular cylindrical shells having multiple intermediate ring supports and various combinations of end support conditions. These exact vibration frequencies may serve as important benchmark values for researchers to validate their numerical methods for such circular cylindrical shell problems.     

横向磁场中导电圆柱壳体的超谐波共振

研究磁场环境中受机械载荷作用圆柱薄壳的三阶超谐波共振问题.在给出横向磁场和机械动载共同作用下圆柱薄壳的振动方程基础上,应用伽辽金积分法,并进行无量纲化处理,进一步导出相应的非线性磁弹性振动微分方程.采用多尺度法对三阶超谐波共振问题进行求解,得到稳态运动下的幅频响应方程与解的稳定性判别式.通过算例,给出几种情况下反映振幅...     

圆柱薄壳结构动态综合优化

根据低噪声水下航行器壳体的设计要求,通过分析水下圆柱壳体结构振动和声辐射特性,及应满足的稳定性和强度要求,得出了低噪声圆柱薄壳结构优化设计方法.运用MATLAB优化工具箱对鱼雷圆柱壳体进行了结构优化设计,通过分析得出该圆柱壳体应满足的约束条件,得出了优化结果.     

Thermoelastic damping in cylindrical shells with application to tubular oscillator structures

Thermoelastic vibration and damping of cylindrical shell structures is studied in this paper. The general thermoelastic coupled equations for cylindrical thin shells are presented first. Since the general governing equations are quite complicated, they are then simplified with Donnell–Mushtari–Vlasov approaches for the cylindrical shells under transverse deflection-dominated vibrations. By solving the simplified thermoelastic equations with Galerkin method, the approximate solutions for thermoelastic damping in a cylindrical shell structure are obtained. The solutions are suitable for the predictions of thermoelastic damping of tubular oscillator structures. Some numerical examples for micro- or nano-tube resonators are provided to illustrate the results.     

Free vibration of a laminated composite shell of revolution: Effects of shear non-linearity

Effects of shear non-linearity on free vibration of a laminated composite shell of revolution are investigated using a semi-analytical method based on the Reissner–Mindlin shell theory. The coupling between symmetric and anti-symmetric vibration modes of the shell is considered in the shear deformable shell element employed in this study. The Hahn–Tsai non-linearly elastic shear stress–shear strain relation is adopted. Numerical examples are given for laminated composite circular cylindrical and conical shells with various boundary conditions. The numerical results indicate that shear non-linearity may reduce significantly the fundamental frequencies of cross-ply composite shells of revolution.     

Vibration of cylindrical shells with ring support

In this paper, a study on the vibration of thin cylindrical shells with ring supports is presented. The cylindrical shells have ring supports which are arbitrarily placed along the shell and which imposed a zero lateral deflection. The study is carried out using Sanders' shell theory. The governing equations are obtained using an energy functional with the Ritz method. Results are presented on the frequency characteristics, influence of ring support position and the influence of boundary conditions. The present analysis is validated by comparing results with those available in the literature.     

Frequency analysis of multiple layered cylindrical shells under lateral pressure with asymmetric boundary conditions

Natural frequency characteristics of a thin-walled multiple layered cylindrical shell under lateral pressure are studied. The multiple layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum. The multiple layered shell equations with lateral pressure are established based on Love＇s shell theory. The governing equations of motion with lateral pressure are employed by using energy functional and applying the Ritz method. The boundary conditions represented by end conditions of the multiple layered cylindrical shell are simply supported-clamped（SS-C）, free-clamped（F-C） and simply supported-free（SS-F）. The influence of different lateral pressures, different thickness to radius ratios, different length to radius ratios and effect of the asymmetric boundary conditions on natural frequency characteristics are studied. It is shown that the lateral pressure has effect on the natural frequency of multiple layered cylindrical shell and causes the natural frequency to increase. The natural frequency of the developed multilayered cylindrical shell is validated by comparing with those in the literature. The proposed research provides an effective approach for vibration analysis shell structures subjected to lateral pressure with an energy method.     

一种分析受爆炸冲击的水下圆柱壳结构强度的方法

根据小型水下圆柱壳状结构受爆炸冲击后散射现象严重的特点，提出一种新的冲击载荷的近似计算方法。首先把带加强筋的实际柱壳状结构简化为与实际结构外形尺寸和低阶振动模态都相同的理想柱壳，并将冲击波分解为不同频率谐和平面波的迭加，然后，采用耦合模态法分析受爆炸冲击水下圆柱壳状结构周围的散射场，求出圆柱壳状水下结构的表面总压，再通过积分求得表面平均总压，并探讨结构的弹性变形、材料特性对它的影响，最后用有限元软件分析某水下工程实际结构受到爆炸冲击后的弹塑性变形时间历程。结果表明，结构的弹塑性变形的时间历程明显落后于表面平均总压的时间历程，即前者的峰值到达时间迟于后者的峰值。工程实例分析的结果表明，本文方法具有物理概念清晰，运用方便，准确度较高的特点，可适用于水下圆柱壳状结构受到冲击后的强度分析。     

柔性结构复合振动的向量控制及实验研究

针对柔性结构复合振动主动控制问题 ,提出了一种向量控制方法。该方法能将复合振动每一频率成分的幅值与相位分开辨识 ,独立控制 ;在控制作用的同时 ,辨识结构的响应向量值 ,当振动幅值变化时 ,实现跟踪控制。同时 ,对薄壁铝合金筒的复合振动向量控制进行了实验研究 ,实验结果表明 ,该方法具有时域和频域控制方法的优点 ,收敛速度快 ,控制精度高 ,振动抑制比达到 90 %以上。