基于改进传递矩阵法的环肋圆柱壳固有振动分析

为了简化传统传递矩阵法中状态向量一阶微分方程复杂推导和得到不同边界条件下环肋圆柱壳的振动特性,基于Flügge壳体理论,通过采用改进传递矩阵法改进状态向量的选取,直接快速地从振动方程推导出圆柱壳结构场传递矩阵,并对场传递矩阵使用精细积分求解。根据环肋和壳体连接处变形连续条件导出环肋处点传递矩。最后通过自由、简支、固支三种不同边界条件下环肋圆柱壳固有频率计算结果与有限元计算结果进行对比,验证了改进传递矩阵法进行环肋圆柱壳振动分析有效性和适用性。     

含环向表面裂纹充液圆柱壳的耦合振动特性分析EI北大核心CSCD

对含环向表面裂纹有限长充液圆柱壳的耦合振动特性进行了研究。在经典薄壳理论中引入基于断裂力学的线弹簧模型来模拟环向表面裂纹;根据理想流体在柱坐标系下的Helmholtz波动方程,通过添加流体载荷项建立了圆柱壳的耦合振动控制方程,采用波传播法描述耦合系统的振动;经优化迭代法有效地计算对应特定固有频率的轴向波数,在此基础上迭代计算满足特定边界条件和裂纹位置连续性条件的固有频率值。为验证方法的准确性,将计算模型分别退化为真空中完善圆柱壳,真空中裂纹圆柱壳,充液完善圆柱壳,三种情况与文献及有限元方法结果进行对比,验证了方法的准确性;讨论了裂纹深度和裂纹位置参数对圆柱壳固有频率改变的影响。     

水中环肋圆锥壳振动特性分析

基于Flügge壳体理论,采用幂级数法研究不同边界条件下水中环肋圆锥壳振动特性。环肋采用刚度各向异性法,平摊等效为壳体重量的增加。通过将圆锥壳分段,且将每段圆锥壳等效为圆柱壳考虑水流体的负载影响。分析水中环肋圆锥壳的固有、受迫振动特性,并通过数值与解析结果对比,验证幂级数法的正确性。研究流体负载、环肋、半锥角及边界条件对其振动特性影响。结果表明,流体负载与环肋主要以附加质量及阻尼形式作用于锥壳。     

含环向表面裂纹充液圆柱壳的耦合振动特性分析

对含环向表面裂纹有限长充液圆柱壳的耦合振动特性进行了研究。在经典薄壳理论中引入基于断裂力学的线弹簧模型来模拟环向表面裂纹;根据理想流体在柱坐标系下的Helmholtz波动方程,通过添加流体载荷项建立了圆柱壳的耦合振动控制方程,采用波传播法描述耦合系统的振动;经优化迭代法有效地计算对应特定固有频率的轴向波数,在此基础上迭代计算满足特定边界条件和裂纹位置连续性条件的固有频率值。为验证方法的准确性,将计算模型分别退化为真空中完善圆柱壳,真空中裂纹圆柱壳,充液完善圆柱壳,三种情况与文献及有限元方法结果进行对比,验证了方法的准确性;讨论了裂纹深度和裂纹位置参数对圆柱壳固有频率改变的影响。     

水下环肋功能梯度材料圆柱壳稳定性研究

研究了水下环肋功能梯度材料圆柱壳的稳定性。根据Flügge理论和正交各向异性板壳理论,采用波动法推导出静水压力下环肋FGM圆柱壳耦合振动特征方程,运用牛顿迭代法得到静水压力下环肋FGM圆柱壳的固有频率值,并通过线性拟合得到静水压力下环肋FGM圆柱壳的临界压力。通过计算对比分析,验证了方法的正确性和有效性。通过算例,分析了静水压力下环肋FGM圆柱壳在不同材料组分、体积分数、壳体尺寸、肋条尺寸和数目等情况下临界压力的变化规律。     

多舱段圆柱壳振动特性研究

基于Flügge壳体理论,采用波动法建立任意边界条件多舱段加筋圆柱壳数理模型,对多舱段圆柱壳固有振动特性和频响特性进行研究。相对于传统的采用平摊或梁模型处理环肋方法,运用圆环板模型分析环肋。在环肋、舱壁等加强构件及激励点处对结构离散,环肋、舱壁等子构件采用圆环板模型分析,激励力作为离散处边界条件,运用离散处连续条件将子构件组装得到运动方程。通过与文献、有限元结果对比验证了本文方法的正确性与准确性,在此基础上分析舱壁厚度、舱壁位置及激励点等参数对多舱段圆柱壳振动特性的影响;并进一步讨论了舱段截断时边界条件选取。     

考虑液体晃荡的部分充液圆柱壳受迫振动分析

充液圆柱壳结构广泛存在于在工程中,在外部激励作用下,圆柱壳会与流体产生耦合振动,且未充满的液面也会产生晃荡,这种耦合振动响应分析在工程中具有重要意义。提出了一种求解考虑内部液体小幅晃荡的弹性圆柱壳振动响应的半解析法。首先分别在壳体建立结构坐标系、在自由液面建立液体坐标系,各自用来描述结构及内部液体的运动。基于Flügge壳体理论建立了圆柱壳的运动控制方程。将液体视为无黏、不可压缩的理想流体,根据线性水波理论和液体自由表面运动边界条件,得出了内部液体的速度势函数。通过流固耦合界面的连续性条件,结合坐标变换推导得到流固耦合系统的运动控制方程。研究了壳体在径向点力激励下振动响应,并得出了对应的液面晃荡响应。和有限元法对比验证了方法的正确性,然后改变相关参数讨论了考虑内部液体晃荡的弹性圆柱壳振动响应特性。     

两端用圆板封口的环肋柱壳振动声辐射性能分析

研究两端用圆板封口的环肋圆柱壳结构在流场中的振动声辐射特性,着重分析了由环肋圆柱壳和端部圆板所围空腔的内部声场对整个系统结构振动和声辐射的影响.基于扩展的Rayleigh-Ritz法,利用Hamilton变分原理推导出圆柱壳与圆板的耦合振动方程.考虑了静水压力的影响,环肋圆柱壳与端部圆板之间采用二自由度弹簧模拟弹性连接的等效刚度.环肋圆柱壳声辐射的研究中,用Helmholtz波动方程和流固交界面上的速度相容条件求得壳体表面辐射声压的表达式,该表达式对有限长圆柱壳进行Fourier积分变换得到壳体外表面辐射声压的解;用Green函数法来求解环肋圆柱壳和端板所围空腔的内部压力场.     

非均匀加筋圆柱薄壳圆截面内振动的径向模态机械阻抗分析

提出圆柱薄壳的圆截面内运动假设,从声学角度将环肋对壳体的作用等效为径向作用力,根据Hamilton原理建立了简支非均匀加筋圆柱壳的振动控制方程,利用驻波形式解对其径向模态机械阻抗进行了研究。分析表明：对于加筋圆柱壳,环肋与圆柱薄壳的径向模态机械阻抗具有串联连接方式,通过调整环肋的几何参数增大环肋自身的径向模态机械阻抗,可以达到壳体减振降噪的目的,并指出了利用环肋的反共振特性进行加筋圆柱壳结构减振的设计方向。     

夹层充液的双层加肋壳体的振动模态分析

基于流体的波动方程和结构的动力方程,利用有限元方法研究了考虑流固耦合时的双层加肋圆柱壳体的振动特性。论文计算了充液夹层圆柱壳体在加肋和不加肋两种情况下的结构模态,分析了影响结构振动的主要因素,为进一步开展水下航行器的研究提供了一定的依据。     

Influence of boundary conditions for a thin laminated rotating cylindrical shell

A study on the influence of boundary conditions for a thin laminated rotating cylindrical shell is presented. The analysis is carried out using Love-type shell theory and solved using Galerkin's method. The displacement fields employed consist of beam functions in the axial direction and fourier functions in the circumferential direction. Extensive results on the influence of boundary conditions and contour plots for the nodal displacements are presented. The analysis has been examined by comparing results with those available in the literature.     

求解地面运动激励下的部分覆盖约束层阻尼贮液圆柱壳耦振的整合状态传递矩阵法

摘要：基于一般情况下的线弹性薄壳方程和势流理论,考虑被动约束层阻尼（PCLD）的剪切变形的能量耗散和液固耦合相互作用,文中首先导出了PCLD圆柱层合壳的整合一阶矩阵微分方程,该方程的状态向量的每个元素都有明确的物理意义,更方便用于层合壳体在各种边界支承条件的动力学问题的求解。然后通过将流体动压力写成含待求系数的解析形式,借助流固交接条件、新型齐次扩容精细积分法和叠加原理,建立了一种分析该类结构耦振问题的高效率、高精度的半解析半数值方法。通过与无水、两端简支的全覆盖PCLD圆柱壳在轴对称情况下自由振动的解析解结果比较,验证了本文方法的有效性。最后基于文中提出的方法,研究了部分覆盖PCLD贮液圆柱容器在地面运动激励下的动力响应,研究了PCLD厚度、长度、敷设位置以及粘弹芯的复剪切模量模型对减振效果的影响。     

复杂边界条件圆柱壳自由振动特性分析

提出一种半解析法来分析圆柱壳结构自由振动特性。将圆柱壳壳结构在轴向方向分解为若干壳段,用沿轴向的Jacobi多项式和沿周向的Fourie r级数来表示各个壳段的位移函数,并采用罚参数法对圆柱壳结构的边界条件和壳段间的连续性条件进行模拟;最后,基于Rayleigh-Ritz法求得圆柱壳结构的自由振动频率。研究表明,该方法具有较好的收敛性,与公开发表文献一致性较高,研究成果可为复杂边界条件下圆柱壳结构自由振动特性分析提供数据积累和方法依据。     

弹性介质中充液圆柱壳的轴对称振动分析

从理论上分析了各向同性弹性介质中有限长充液圆柱壳的自由振动特性。利用经典FLUGGE壳体运动方程,结合弹性动力学方程,得到了弹性介质中充液圆柱壳耦合系统的特征方程。利用数值方法得到了弹性介质中圆柱壳中空和充液时的实固有频率。计算结果表明弹性介质中圆柱壳的实固有频率比真空中圆柱壳的实固有频率高,而且存在截止轴向模态。弹性介质刚度不仅对充液圆柱壳的实固有频率影响显著,而且影响其截止轴向模态。     

Vibration characteristics of fluid-filled cylindrical shells based on elastic foundations

In this paper, vibrations of fluid-filled isotropic circular cylindrical shells are studied based on elastic foundations. The wave propagation approach is employed to solve the shell problem. This approach is formulated by approximating the eigenvalues of the characteristic beam functions. Vibrations of natural frequencies for both empty and fluid-filled cylindrical shells based on elastic foundations are evaluated and their comparisons are performed to confirm the validity and accuracy of the present method. An excellent agreement has been found between the present and previous ones available in the literature. It is observed that frequencies are strongly affected when a cylindrical shell is attached with elastic foundations.     

Free vibration of specially orthotropic,multilayered, thin cylindrical shells with various end conditions

The dynamic response of multilayered, specially orthotropic, thin, circular cylindrical shells is analysed using Love's first-approximation shell theory by the use of Rayleigh-Ritz variational procedure. A powerful tool is developed to calculate the natural frequencies for a variety of shell end conditions—clamped-free, clamped-supported, clamped-clamped, etc.—unlike most existing works, which are confined mainly to simply supported end conditions. The influence of various boundary conditions on the modal behaviour of a cylindrical shell is studied, and natural frequency calculations are established for a wide domain of shell geometries, using an appropriate dimensionless shell-geometrical parameter. The results of the present analysis are shown to compare very well with some available experimental results, in the case of an isotropic cylinder. Similar comparisons are not possible for the orthotropic case because of the nonavailability of previous results. Graphical illustrations of the results corresponding to the cases of various shell-geometrical and material parameters are provided for various end conditions.     

Dynamic elastic response of an infinite discrete multi-layered cylindrical shell subjected to uniformly distributed pressure pulse

A discrete multi-layered cylindrical shell (DMC) consists of a thin inner cylindrical shell and helically cross-winding flat steel ribbons. The dynamic elastic response of such cylindrical shell under uniformly distributed pressure pulse is studied in this paper. Under the axisymmetric plane strain assumption, the solution of the problem is divided into two parts: a quasi-static part satisfying inhomogeneous stress boundary conditions and a dynamic part complying with homogeneous stress boundary conditions. The quasi-static part is determined by homogeneous linearity method and boundary conditions, and the dynamic part was worked out by means of finite Hankel transform and Laplace transform. The dynamic response of a DMC is compared with the response of monobloc cylindrical shell. Parametric analyses with the consideration of major influential factors, such as thickness ratio of the inner shell to that of the complete shell, material parameters and winding-angle, are discussed.     

模态数量对薄壁短圆柱壳振动响应分析的影响

采用振型叠加法研究薄壁短圆柱壳受谐波激励的振动响应分析时模态截断数量的影响,且考虑简支-简支、固支-固支和固支-自由三种约束条件。首先基于Love壳体理论建立薄壁短圆柱壳的动力学模型。然后,给出采用振型叠加法进行薄壁短圆柱壳受径向谐波激励时的振动响应求解方法。在三种不同约束条件下,计算采用不同模态截断数量时的稳态响应的振动幅值,对比其一致性,并与实测结果进行比较。结果表明,在这三种约束条件下计算受谐波激励薄壁短圆柱壳的振动响应,需要截取前8阶模态函数用于表征位移模式;模态数据超过8阶对响应计算的精度没有明显改善,实测振动响应结果与解析结果基本吻合。     

Static analysis of functionally graded cylindrical shell with piezoelectric layers using differential quadrature method

Three-dimensional solution for static analysis of functionally graded (FG) cylindrical shell with bonded piezoelectric layers is presented using differential quadrature method (DQM) and state-space approach. Applying the DQM to the governing differential equations and to the edges boundary conditions, new state equations about state variables at discrete points are derived. The stress, displacement, and electric potential distributions are obtained by solving these state equations. The convergence and accuracy of the present method is validated by comparing numerical results for the hybrid FG cylindrical shell with simply-supported edges with the analytical solution that has been published in the literature. Both the direct and the inverse piezoelectric effects are investigated and the influence of piezoelectric layers and gradient index on the mechanical behavior of shell is studied.     

Study of the effect of in-plane and interlaminar stresses on damping in fluid-filled laminated composite cylinders

The modal strain energy method is used in conjunction with a three-dimensional finite element analysis in the characterization of the effects of in-plane and interlaminar stresses in fluid-filled composite laminate cylindrical shells. A semi-analytical, 8-noded isoparametric finite element, which includes both the symmetric and antisymmetric modes in the circumferential direction, is used in the analysis. The effects of fiber angle, contained fluid height, size parameter of the shell, and stacking sequence on the contribution of in-plane and interlaminar stresses to the overall system damping in fluid-filled, composite laminate cylindrical shells are studied.