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New matrix method for analyzing vibration and damping effect of sandwich circular cylindrical shell with viscoelastic core 总被引:2,自引:0,他引:2
Based on the linear theories of thin cylindrical shells and viscoelastic materials, a governing equation describing vibration of a sandwich circular cylindrical shell with a viscoelastic core under harmonic excitation is derived. The equation can be written as a matrix differential equation of the first order, and is obtained by considering the energy dissipation due to the shear deformation of the viscoelastic core layer and the interaction between all layers. A new matrix method for solving the governing equation is then presented With an extended homogeneous capacity precision integration approach. Having obtained these, vibration characteristics and damping effect of the sandwich cylindrical shell can be studied. The method differs from a recently published work as the state vector in the governing equation is composed of displacements and internal forces of the sandwich shell rather than displacements and their derivatives. So the present method can be applied to solve dynamic problems of the kind of sandwich shells with various boundary conditions and partially constrained layer damping. Numerical examples show that the proposed approach is effective and reliable compared with the existing methods. 相似文献
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该文在对空圆柱层合壳(不充液)振动分析研究的基础上,借助线性势流理论,进一步考虑液固耦合效应,导出了敷有CLD贮液圆柱层合壳谐耦振的一阶常微分矩阵方程,该方程右边多了液动压力项.由于它不能预先给定,导致方程中出现未知项.为了克服这一困难,文中研究了液动压力的解式,并采用新型齐次扩容精细积分技术,提出了一种高效率和高精度的半解析半数值解法.进而还求解了CLD贮液圆柱容器在地面谐运动激励下的响应;通过大量数值计算分析了CLD的厚度、长度、敷设位置以及粘弹芯的复剪切模量对减振效果的影响.计算还表明了有液体的存在,这些影响和空容器时是不一样的.文中方法为CLD贮液容器的控制优化提供了有力手段. 相似文献
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A new model for a smart shell of revolution treated with active constrained layer damping (ACLD) is developed, and the damping effects of the ACLD treatment are discussed. The motion and electric analytical formulation of the piezoelectric constrained layer are presented first. Based on the authors~ recent research on shells of revolution treated with passive constrained layer damping (PCLD), the integrated first-order differential matrix equation of a shell of revolution partially treated with ring ACLD blocks is derived in the frequency domain. By virtue of the extended homogeneous capacity precision integration technology, a stable and simple numerical method is further proposed to solve the above equation. Then, the vibration responses of an ACLD shell of revolution are measured by using the present model and method. The results show that the control performance of the ACLD treatment is complicated and frequency-dependent. In a certain frequency range, the ACLD treatment can achieve better damping characteristics compared with the conventional PCLD treatment. 相似文献
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Mousa Khalifa Ahmed 《基于设计的结构力学与机械力学》2016,44(3):161-175
For the first time, a new cross-section profile and efficient method are developed for the vibration analysis of isotropic and orthotropic cylindrical shells having circumferentially varying profile of a cardioid cross-section expressed as an arbitrary function, under thermal gradient effect. The governing equations of orthotropic cylindrical shells with varying thermal gradient around its circumference are derived as a boundary-value problem and solved numerically as an initial-value problem, based on the framework of Flügge's shell theory, transfer matrix approach and Romberg integration method. As a semi-analytical procedure, the trigonometric functions are used with Fourier's approach to approximate the solution in the longitudinal direction and also to reduce the two-dimensional problem to one-dimensional one. The thermal gradient is assumed to arise due to the variation of Young's moduli and shear modulus, along the circumferential direction of the shell. The results are obtained to indicate the effects of cardioid cross-section on the natural frequencies and corresponding mode shapes in the thermal environment as well as the sensitivity of the vibration behavior to the thermal gradient ratio and the orthotropy of the shell is also investigated for different types of vibration modes. In general, close agreement between the obtained results and those of other researchers has been found. 相似文献
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设计了一个层叠式PVDF压电作动器用于壳结构的振动控制。考虑压电层、粘接层、壳体耦合关系,推导了表面局部粘贴层叠式PVDF压电作动器的圆柱壳的振动控制方程,给出了作动力与压电层和粘接层层数、厚度之间的关系以及作动力与作动器粘贴位置之间的关系。针对一端固定、另一端自由的圆柱壳,进行了振动控制仿真。结果表明层叠式PVDF压电作动器作动力与作动器层数近似成线性关系,增大作动器层数能有效增大作动力,在低控制电压下能显著抑制圆柱壳振动,作动器周向不完全粘贴时,在径向产生的径向作动力对壳体横向振动控制非常有利。说明了层叠式PVDF压电作动器是一种可用于壳体结构振动并具有良好作动效果的作动器。 相似文献
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G. P. Gulgazaryan 《International Applied Mechanics》2008,44(5):534-554
The natural vibrations of a cantilever thin elastic orthotropic circular cylindrical shell are studied. Dispersion equations
for the determination of possible natural frequencies of cantilever closed shells and open shells with Navier hinged boundary
conditions at the longitudinal edges are derived from the classical dynamic theory of orthotropic cylindrical shells. It is
proved that there are asymptotic relationships between these problems and the problems for a cantilever orthotropic strip
plate and for a cantilever rectangular plate and the eigenvalue problem for a semi-infinite closed orthotropic cylindrical
shell with free end and for the same but open shell with Navier hinged boundary conditions at the longitudinal edges. A procedure
to identify types of vibrations is presented. Orthotropic cylindrical shells with different radii and lengths are used as
an example to find approximate values of the dimensionless natural frequency and damping factor for vibration modes
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Translated from Prikladnaya Mekhanika, Vol. 44, No. 5, pp. 68–91, May 2008. 相似文献
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The extensive use of circular cylindrical shells in modern industrial applications has made their analysis an important research area in applied mechanics. In spite of a large number of papers on cylindrical shells, just a small number of these works is related to the analysis of orthotropic shells. However several modern and natural materials display orthotropic properties and also densely stiffened cylindrical shells can be treated as equivalent uniform orthotropic shells. In this work, the influence of both material properties and geometry on the non-linear vibrations and dynamic instability of an empty simply supported orthotropic circular cylindrical shell subjected to lateral time-dependent load is studied. Donnell׳s non-linear shallow shell theory is used to model the shell and a modal solution with six degrees of freedom is used to describe the lateral displacements of the shell. The Galerkin method is applied to derive the set of coupled non-linear ordinary differential equations of motion which are, in turn, solved by the Runge–Kutta method. The obtained results show that the material properties and geometric relations have a significant influence on the instability loads and resonance curves of the orthotropic shell. 相似文献
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In this study, the torsional vibration and stability problems of functionally graded (FG) orthotropic cylindrical shells in the elastic medium, using the Galerkin method was investigated. Pasternak model is used to describe the reaction of the elastic medium on the cylindrical shell. Mixed boundary conditions are considered. The material properties and density of the orthotropic cylindrical shell are assumed to vary exponentially in the thickness direction. The basic equations of the FG orthotropic cylindrical shell under the torsional load resting on the Pasternak-type elastic foundation are derived. The expressions for the critical torsional load and dimensionless torsional frequency parameter of the FG orthotropic cylindrical shell resting on elastic foundations are obtained. The effects of variations of shell parameters, the exponential factor characterizing the degree of material gradient, orthotropy, foundation stiffness and shear subgrade modulus of the foundation on the critical torsional load and dimensionless torsional frequency parameter are examined. 相似文献
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基于弹性、粘弹性和压电材料本构方程,应用能量法建立了主动约束层阻尼(ACLD)圆柱壳体的有限元动力学方程。通过对压电传感层自感电压的比例、微分反馈控制,对主动约束层阻尼(ACLD)圆柱壳体进行了主被动一体化振动控制,研究了复合圆柱壳体的动力学响应特性。讨论了主动约束层阻尼(ACLD)片体的位置、覆盖率、粘弹性层厚度及控制增益等关键参数对圆柱壳体振动特性的影响。研究表明:主动约束层阻尼(ACLD)片体的粘贴位置与模态有关,针对不同模态,应采用不同的粘贴位置;覆盖率、粘弹性层厚度及控制增益等直接影响到振幅衰减程度,通过对片体位置、覆盖率、粘弹性层厚度及控制增益等关键参数的优化,能有效降低主动约束层阻尼圆柱壳体的振动,具有十分重要的工程应用价值。 相似文献
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The first order differential matrix equations of the host shell and constrained layer for a sandwich rotational shell are derived based on the thin shell theory.Employing the layer wise principle and first order shear deformation theory, only considering the shearing deformation of the viscoelastic layer, the integrated first order differential matrix equation of a passive constrained layer damping rotational shell is established by combining with the normal equilibrium equation of the viscoelastic layer.A highly precise transfer matrix method is developed by extended homogeneous capacity precision integration technology.The numerical results show that present method is accurate and effective. 相似文献
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The stress–strain distribution in a composite deep cylindrical shell is analyzed. The shell is weakened by a circular opening and loaded by an axial force. The problem is solved by the variational difference method. The analysis is carried out for an orthotropic shell with low shear stiffness 相似文献
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Based on flügge's thin orthotropic shell equations and a linear potential flow theory, buckling instability and flutter-type instability of orthotropic circular cylindrical shells conveying fluid are studied. By means of the expansion in beam-mode functions and Galerkin's method they can be reduced to solving a generalized complex eigenvalue problem. In calculating the generalized forces defined as Eq. (23), a direct numerical integration technique, which has proven to be more efficient than others, is used. For clamped-clamped orthotropic shells several numerical examples show that the effects of axial elastic modulus on the dynamic behaviors are quite different from those of circumferential elastic modulus. 相似文献
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Bakhtiyor Eshmatov 《应用数学和力学(英文版)》2007,28(10):1319-1330
The present work discusses the problem of dynamic stability of a viscoelas- tic circular cylindrical shell,according to revised Timoshenko theory,with an account of shear deformation and rotatory inertia in the geometrically nonlinear statement.Pro- ceeding by Bubnov-Galerkin method in combination with a numerical method based on the quadrature formula the problem is reduced to a solution of a system of nonlinear integro-differential equations with singular kernel of relaxation.For a wide range of vari- ation of physical mechanical and geometrical parameters,the dynamic behavior of the shell is studied.The influence of viscoelastic properties of the material on the dynamical stability of the circular cylindrical shell is shown.Results obtained using different theories are compared. 相似文献
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B. Kh. Eshmatov 《Nonlinear dynamics》2007,50(1-2):353-361
The vibration problem of a viscoelastic cylindrical shell is studied in a geometrically nonlinear formulation using the refined
Timoshenko theory. The problem is solved by the Bubnov–Galerkin procedure combined with a numerical method based on quadrature
formulas. The choice of relaxation kernels is substantiated for solving dynamic problems of viscoelastic systems. The numerical
convergence of the Bubnov–Galerkin procedure is examined. The effect of viscoelastic properties of the material on the response
of the cylindrical shell is discussed. The results obtained by various theories are compared. 相似文献
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蜂窝锥壳卫星适配器约束阻尼层振动抑制分析 总被引:5,自引:3,他引:5
主要研究在蜂窝锥壳卫星适配器上附加约束阻尼来抑制锥壳传递振动。尽管约束阻尼方面的研究很多,但是大多数都是针对简单的梁或者板结构,而对复杂蜂窝锥壳结构的振动抑制问题研究还很少;为此,通过对蜂窝壳的等效化处理和约束阻尼结构的有限元建模理论分析,建立起卫星一适配器结构在有无附加约束阻尼情况下的有限元模型,进一步通过模态分析和频响分析,得到不同约束阻尼层设计参数对结构振动抑制影响规律。分析结果对于经济有效的设计约束阻尼层和结构减振减重具有较好的参考价值。 相似文献
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IntroductionTherearerarepapersonthedynamicPropertiesofviscoelasticshells.~ulosl']discussesthecaseofshallowsphericalshellandDrozdov[ZIgivesasufficientcondihonofstabilityfortheviscoelasticcylindershellbyusingtheLyapunovfunchonal.UsingtheLyapunovdirectmethod,Tyllkowski[']establishesasufficientconditionfortheasymptohcstabilityofviscoelasticcylindricalshell.ItisnotdifficulttofindthattheseexistingresultSmainlyconcentrateonthedynamicstabilityofviscoelasticshell.Thediscussionaboutthedynamicalsyste… 相似文献