共查询到19条相似文献,搜索用时 62 毫秒
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采用与以往解析法和FEM/BEM不同的思路,通过运用Riccati传递矩阵法和齐次扩容精细积分法求解水下圆柱壳声振问题的一阶矩阵微分方程,提出一种新的半解析半数值法分析有限长环肋圆柱壳的声振问题。声压解析表达式由满足Helmholtz方程的基本解的线性组合表示;利用液固交界面的法向速度协调条件以及在壳体母线上配点,从而将结构的声振耦合方程转化为求解声压系数的线性代数方程组,实现了对环肋圆柱壳声振问题的求解。数值算例研究了几个重要计算参数对精度的影响;另外通过结果比较表明了该方法的有效性。该方法可以进一步推广到求解有限长环肋圆锥壳以及环肋锥壳组合壳的声振问题。 相似文献
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考虑剪切效应的环肋圆柱壳的稳定性 总被引:2,自引:0,他引:2
基于Reissner-Naghdi壳体理论和Timoshenko环梁理论,采用Ritz法对环肋圆柱壳的稳定性进行了研究。在简支边界条件下考虑了壳体和环肋的剪切变形效应对临界载荷的影响。由于环肋会约束壳体的变形,壳体的前屈曲状态应该是有弯曲变形的,环向压缩力也是非均匀分布的,分析了这一因素的影响。算例的计算结果与文献中给出的实验值吻合较好,并表明壳体的剪切效应在一些情形下会对环肋圆柱壳的稳定性产生一定的影响。 相似文献
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环加肋圆柱壳振动分析的复合有限条法 总被引:2,自引:0,他引:2
提出一种分析环加肋圆柱壳自由振动问题的高效半解析方法──复合有限条法。该方法可在一个有限条元内计入若干个横向加肋的影响,包含横向加肋的有限条元称为复合有限条元,环加肋圆柱天采用一系列复合有限条元进行离散。复合有限条法可按加强肋骨的实际分布情况进行计算,而不必采用将加肋的影响平均到整个壳体的方法,且可考虑肋骨偏心的影响,它是一种子结构求解技术。算例表明,复合有限条法具有良好的求解精度和很高的求解效率,与常规有限元法相比,复合有限条法大大减少了系统自由度和计算工作量,且易于程序实现,是一种分析加肋板壳结构振动问题的较理想方法。 相似文献
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水下爆炸冲击波作用下自由环肋圆柱壳动态响应的数值仿真研究 总被引:5,自引:7,他引:5
运用大型商业有限元程序MSC.DYTRAN数值模拟了水下爆炸冲击波作用下自由环肋圆柱壳的非线性动 态响应。采用一般耦合算法(generalcoupling)模拟流体与结构的耦合效应,计算中考虑了材料的应变率强化效应,几何 非线性以及结构的初始缺陷的影响,计算结果与实验吻合较好。比较了肋骨和肋间壳板在迎爆面,侧爆面和背爆面处的 中面有效应力和应变,分析了壳体在三个不同部位的破坏机理。最后比较了计算中考虑应变率效应与否对壳体最终变 形的影响。 相似文献
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钢筋混凝土圆柱壳声辐射特性的有限元研究 总被引:1,自引:0,他引:1
空气中两端简支支撑的钢筋混凝土加肋壳体的声辐射问题,由于加强钢筋及环肋的作用增加了系统共振频谱的复杂性,用解析的方法解决此类问题存在困难。利用有限元软件ANSYS,分析了内部空气及环肋数量对壳体声辐射特性的影响。计算结果表明,在低频情况下,内部空气对壳体的声辐射特性影响不大,采取合理的加肋措施可降低结构的辐射声压级。 相似文献
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Doo-Sung Lee 《Journal of Engineering Mathematics》2000,38(2):141-154
Dynamic buckling of an orthotropic cylindrical shell which is subjected to rapidly applied compression is considered. A nonlinear differential equation of Donnell–Karman type is derived with the initial imperfection taken into account. An energy method is used to obtain the equation of motion which is then solved numerically by means of a Runge-Kutta method. These numerical results show that the critical load is increased over the corresponding static case. An analytical solution is also obtained for the problem of hydrostatic pressure. 相似文献
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A.V. LopatinE.V. Morozov 《Composite Structures》2012,94(2):553-562
In this paper a solution is presented for a buckling problem formulated for the cantilever circular cylindrical composite shell subjected to uniform external lateral pressure. The edge of the shell is fully clamped at one end of the cylinder and is free at the open section of the other end. An analytical formula for critical pressure has been derived using the generalised Galerkin method. The approach is illustrated by the buckling analyses of composite, orthotropic and isotropic shells. The results are verified using the finite-element method. It has been shown that the analytical solution provides an accurate estimate of the critical load and does not involve any computationally expensive procedures. This is particularly useful in the design optimisation of composite structures. 相似文献
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YongLiang Zhang Jason M. Reese Daniel G. Gorman 《International journal for numerical methods in engineering》2002,54(1):89-110
A comparative study of the relative performance of several different axisymmetric finite elements, when applied to the dynamic problem of thin cylindrical shells conveying fluid, is presented. The methods used are based on (1) the Sanders' theory of thin shells and the potential flow theory, and (2) the theory of elasticity and the Euler equations. The elements studied are: linear, paralinear, parabolic and cubilinear. Extensive comparison with experiment is carried out for the free vibration of cylindrical shells in the absence of, and containing, quiescent and flowing fluid. The analysis of the relative competence of these elements is presented for shell length‐to‐radius ratios 1.95≤L/R≤32, shell radius‐to‐thickness ratios 10≤R/h≤375 and boundary conditions: clamped–clamped, clamped–free and simply supported. We show that natural frequencies of thin cylindrical shells in the absence of, and containing, quiescent and flowing fluid can be assessed accurately when using two‐ and eight‐noded elements, and the latter are also applicable to the dynamic problem of thick cylindrical shells. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Non-linear buckling and postbuckling of a moderately thick anisotropic laminated cylindrical shell of finite length subjected to lateral pressure, hydrostatic pressure and external liquid pressure has been presented in the paper. The material of each layer of the shell is assumed to be linearly elastic, anisotropic and fiber-reinforced. The governing equations are based on a higher order shear deformation shell theory with von Kármán–Donnell-type of kinematic non-linearity and including the extension/twist, extension/flexural and flexural/twist couplings. The non-linear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine the buckling pressure and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling response of perfect and imperfect, moderately thick, anisotropic laminated cylindrical shells with different values of shell parameters and stacking sequence. The results confirm that there exists a circumferential stress along with an associate shear stress when the shell is subjected to external pressure. 相似文献
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The generalized ray method (GRM) and the method of reverberation ray matrix (MRRM) have been successfully used to study the transient elastic wave transmission in the beams, planar trusses, space frames and infinite layered media. In this paper, the GRM and MRRM are extended to investigate the early short time transient responses of laminated composite cylindrical shells with finite size under impact load. Using the Laplace transformation, the ray groups transmitting in the laminated cylindrical shells under the shock load are yielded by means of the boundary conditions. The reverberation-ray matrix representing the multi-reflected and scattered waves in the laminated cylindrical shells with finite structural size is deduced. Using FFT algorithm, the transient response corresponding to each ray group can be derived. Through the numerical simulations, it is seen that the early short time transient accelerations of the laminated composite cylindrical shells under impact loads are very large, but the early short time transient shear strain and displacement are very small. Furthermore, the effects of the stacking sequence, thickness of the composite cylindrical shells and different shock loads on the early short time transient responses of the laminated composite cylindrical shells with finite size are also analyzed. 相似文献
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采用波传播法研究了低频下水中壳体的振动与响应。水中壳体由有限长加流体载荷的圆柱壳和两端的圆形端板组成,其中外部流体载荷用无限长模型进行近似处理。为了模拟推动系统的激励及船体上某一点激励,分别考虑了不同位置的轴向载荷和径向载荷,讨论了单个周向模态下的位移在总位移中的比重。主要研究了4种载荷,即作用在端板中心的轴对称载荷、作用在端板与圆柱连接处的轴向载荷、作用在连接处的径向载荷和作用在壳体中间的径向载荷,比较得出了轴对称和非轴对称、同一点不同方向载荷、同一方向不同位置载荷的响应位移的不同。此外,还研究了两端端板对不同载荷下水中壳体响应的影响,得出了端板主要抑制了壳体的较高阶模态下径向位移的结论。解析法结果与有限元法结果进行了比较,验证了该方法的正确性。 相似文献
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H. Dalayeli H. Hashemolhosseini M. Farzin B. Soltani 《International journal for numerical methods in engineering》2006,65(9):1403-1418
Most of the existing numerical methods based on penalty technique, lead to pressure fields, which are not satisfactory especially when crude meshes are used. The present work for the first time, using a simple and effective finite point approach approximates the total hydrostatic stresses. By this new technique, the nodal hydrostatic pressure values are calculated so that the gradient of hydrostatic pressure satisfies the equilibrium equation, with regard to the current distribution of deviatoric stresses. This approach is verified using a cantilever beam with known analytical stress field. It is also applied to a typical 2D axisymmetric bulk metal forming process. The calculated pressure field is then compared with available solutions. The results of the present approach are very encouraging. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献