封闭圆柱壳振动响应特性研究

用均值导纳法分析了复杂的圆柱壳组合结构振动响应特性 ,取得了较好的结果。主要是将均值导纳法用于封闭圆柱壳体振动能量比的研究 ,实验结果证明用均值导纳法来研究封闭圆柱壳的振动响应是可行的。     

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.     

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。     

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。     

随机天线结构在随机风荷激励下的动力分析

研究了具有随机参数的天线结构在随机风荷激励下的动力响应问题。从天线结构在随机风荷激励下振动响应在频域上的表达式出发,将天线结构物理参数、几何尺寸和结构阻尼均视为随机变量,利用求解随机变量函数矩的方法和求解随机变量数字特征的代数综合法,导出了随机天线结构在随机风荷激励下位移响应均方值和应力响应均方值的均值、方差和变异系数的计算表达式。算例分析表明了天线结构参数的随机性对其在随机风荷激励下位移响应均方值和应力响应均方值随机性的影响。     

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。     

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。     

有限薄板面导纳的计算方法

面导纳是对传统的点导纳 (或阻抗 )概念的一个新的发展 ,它在考虑了激励面积尺寸和激振力分布形态的影响后 ,能够比点导纳更准确地描述激振源与其支撑结构之间的能量传递的动态特性。但前期面导纳的研究主要是以无限大结构模型作为研究对象 ,所以其研究结果的应用受到一定条件的限制。本文根据工程实际的需要 ,以实际中最常见的有限矩形板为支撑结构 ,探索受到矩形大面积激励下二维面导纳的计算方法及振动能量传递的特性。本文中推导出了受均布力激励的有限薄板矩形面导纳的理论计算方法 ,并对两对边简支两对边自由的薄板模型进行了面导纳的计算。为了分析激励面积的形状对面导纳的影响 ,采用了两种不同长宽比的激励面积。通过对计算结果的分析和与无限大板面导纳的比较可以看出 ,无限板与有限板面导纳有明显的不同 ,面导纳理论对结构的隔振设计和结构中振动能量流的研究都有重要意义     

压水堆燃料棒湍流激励流致振动响应计算方法研究

当湍流流过燃料棒表面时,湍流速度分量产生表面随机压力脉动。采用随机振动响应的模态分析技术,得出圆柱体横向振动位移的均方值一般表达形式。根据压水堆燃料棒的结构和流场分布特征,将作用在燃料棒上的流体力等效为脉动随机载荷,引入湍流功率谱密度函数,结合相关功率谱密度试验参数,推导每阶模态的振动位移均方值。分别讨论轴向和横向流引起的各阶模态的振动幅值,并给出各阶模态的对数衰减阻尼,轴向和横向流引起的振动幅值采用线性组合方法,对各阶模态的采用10%的模态组合方法得到所有模态的燃料棒振动幅值,给出了完整的燃料棒轴向和横向湍流激励振动总幅值的通用计算方法和分析流程。     

水下弹性圆柱壳结构声辐射有源控制研究

研究了利用次级环带声源对水下有限长弹性圆柱壳结构振动声辐射进行有源控制。给出了初级圆柱和次级环带声源之间的互辐射阻抗计算公式,考虑流固耦合效应,利用二次最优理论,以辐射声功率最小化为目标函数,得到次级环带声源的最优激励力,最后计算控制前后远场辐射声压的空间分布。结果表明:利用次级环带声源可以对弹性圆柱壳结构振动辐射噪声进行控制,增大次级环带声源与初级圆柱壳间距,控制效果变差;次级激励力位置对辐射声功率控制效果也会产生影响。     

Frequency response analysis of cylindrical shells conveying fluid using finite element method

A finite element vibration analysis of thin-watled cylindrical shells conveying fluid with uniform velocity is presented The dynamic behavior of thin-walled shell is based on the Sanders’ theory and the fluid in cyhndrical shell is considered as inviscid and incompressible so that it satisfies the Laplace’s equation A beam-like shell element is used to reduce the number of degrees-of-freedom by restricting to the circumferential modes of cylindrical shell An estimation of frequency response function of the pipe considering of the coupled effects of the internal fluid is presented A dynamic coupling condition of the interface between the fluid and the structure is used The effective thickness of fluid according to circumferential modes is also discussed The influence of fluid velocity on the frequency response function is illustrated and discussed The results by this method are compared with published lesults and those by commercial tools     

开孔圆柱壳模拟疲劳试验模型及加载条件的研究

研究受内压开孔圆柱壳与其受拉伸开孔平板模型在结构和受载条件上的相似性，有限元分析表明，开孔圆柱壳与其相应的平板模型在开孔附近的等效应力分布非常相似，分析和试验结果表明，开孔圆柱壳模拟疲劳试验载荷应由控制疲劳寿命的关键部位（即危险点）的等效应力来确定，当开孔圆柱壳与其平板模型在危害点的等效应力水平和分布相同时，可认为二者的疲劳寿命也相同，在正确的加载条件下，开孔平板模型可用于开孔圆柱壳的模拟疲劳试验，并较精确地预测开孔圆柱壳的疲劳寿命。     

Thermally induced vibration control of cylindrical shell using piezoelectric sensor and actuator

Shell type components and structures are very common in many mechanical and structural systems. Modeling and analysis of adaptive piezothermoelastic shell laminates represent a high level of sophistication and complexity. In this paper a finite element model is developed for the active control of thermally induced vibration of laminated composite shells with piezoelectric sensors and actuators. The present model takes into account the mass, stiffness and thermal expansion of the piezoelectric patches. A C_o continuous nine-node degenerated shell element is implemented to model the structure. The piezoelectric sensing layer senses the structural vibration and a suitable voltage applied in the piezoelectric actuator layer suppresses the oscillation. Actuator and sensor are coupled together with a control algorithm so as to actively control the dynamic response of the structure in a close loop. Numerical results are generated for a cylindrical shell and it is observed that thermally induced vibration of a laminated cylindrical shell can be suppressed through the application of piezoelectric sensor and actuator. Effects of variation in control gain and piezoelectric layer area coverage (PAC) have been studied. Higher control gain is more effective in damping out the vibration. Although the damping is enhanced by increase in PAC, increase beyond a certain level may not be useful in view of smaller efficacy and increased weight.     

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.     

异径弯管的无力矩环向应力解析解

提出以异径管单位高度（长度）的直径变化程度作为反映异径管结构特征的无因次量，并定义为异径系数。根据异径弯管横截面管径随经向弯角而变化及其锥形结构的两个特点，推导了内压作用下异径弯管无力矩环向应力武，最大环向应力位于大端内侧。该武可以作为工程中常见回转壳无力矩环向应力式的任意条件式，等径弯管、直管及异径直管的环向应力公式均是异径弯管环向应力武的一个特定条件的特例，本质上这些公式均是环向应力的薄膜解。计算环向薄膜应力时，一般来说．工程中各种鼻径管与连接直管之间的边缘应力可以忽略。     

一种可调加速度放大率装置的结构与仿真设计

为了在产品的随机振动过程中实现加速度放大率可调节,从材料力学、振动理论等知识出发,设计出一种加速度放大率可调装置,理论放大率调节范围为2.2～5.4,并通过数值仿真和振动试验对其放大效果进行了验证.结果表明,文中提出的加速度放大率理论计算公式准确可靠,此装置加速度放大效果良好且装置结构简单,适用性好.此理论公式与装置可...     

Frequency analysis of submerged cylindrical shells with the wave propagation approach

The wave propagation approach is extended to coupled frequency analysis of finite cylindrical shells submerged in a dense acoustic medium. Comparison of the results by the present method and numerical FEM/BEM has been carried out. A finite cylindrical shell enclosed with plate end-caps was modeled for coupled frequency analysis. The first eight coupled natural frequencies were obtained using SYSNOISE. These results are compared with the new method and good agreement has been found. With the new method the effects of shell parameters, m,n,h/R,L/R and boundary conditions, on the coupled frequencies are investigated. The coupled frequency curves are also u-shaped as the uncoupled frequency curves. As the circumferential mode n increases, the difference between the coupled and uncoupled frequencies reduces at small mode n, but increases after the n where the fundamental frequency is achieved. The effects of boundary conditions are significant at small mode n. Due to the coupling effects the transition of fundamental coupled frequency is earlier with the h/R ratios than that of the uncoupled case. Both the coupled and uncoupled frequencies increase with the h/R ratios, but at different rates which show the different coupling effects on the different wave modes. With the present method the calculation of coupled frequency of submerged cylindrical shells is relatively easy, quick but with good accuracy.     

THEORETICAL PREDICTION OF SOUND RADIATION FROM A HEAVY FLUID-LOADED CYLINDRICAL COATED SHELL

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A novel prediction method of vibration and acoustic radiation for rectangular plate with particle dampers

Particle damping technology is widely used in mechanical and structural systems or civil engineering to reduce vibration and suppress noise as a result of its high efficiency, simplicity and easy implementation, low cost, and energy-saving characteristic without the need for any auxiliary power equipment. Research on particle damping theory has focused on the vibration response of the particle damping structure, but the acoustic radiation of the particle damping structure is rarely investigated. Therefore, a feasible modeling method to predict the vibration response and acoustic radiation of the particle damping structure is desirable to satisfy the actual requirements in industrial practice. In this paper, a novel simulation method based on multiphase flow theory of gas particle by COMSOL multiphysics is developed to study the vibration and acoustic radiation characteristics of a cantilever rectangular plate with Particle dampers (PDs). The frequency response functions and scattered far-field sound pressure level of the plate without and with PDs under forced vibration are predicted, and the predictions agree well with the experimental results. Results demonstrate that the added PDs have a significant effect on vibration damping and noise reduction for the primary structure. The presented work in this paper shows that the theoretical work is valid, which can provide important theoretical guidance for low-noise optimization design of particle damping structure. This model also has an important reference value for the noise control of this kind of structure.