共查询到19条相似文献,搜索用时 109 毫秒
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阻尼复合圆柱壳体声振特性理论研究进展与现状 总被引:3,自引:1,他引:2
本文综述了60年代以来具有粘弹阻尼层的复合圆柱壳体声振特性,阐述了不同阻尼处理的复合圆柱壳体振动与阻尼特性的研究,以及该类壳体在声特性方面的研究,为进一步开展这方面的工作提供参考。 相似文献
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研究了不同壳间连接介质的加筋双层壳的振动声辐射特性.基于Flügge壳体理论和Helmholtz波动方程,求解了双壳体声-流体-结构耦合方程,计算了有限长双层壳体在径向点激励下的声功率和振动速度级.结果表明,水层的耦合作用随频率的增高而降低,托板的耦合作用随频率的增高而增加,托板在内、外壳的振动传递中起着较大的作用.为了减小托板对振动及声辐射的影响,提出了阻尼托板结构,即在托板上添加阻尼材料,对含阻尼托板的圆柱壳声学特性进行了数值研究.结果表明,在中高频段,阻尼有效抑制了振动能量的传递,壳体的辐射声压明显降低,这对水下结构的减振降噪设计具有重要的参考意义. 相似文献
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在原有的简单锥-柱壳体的基础上,以肋骨、舱壁加强的锥-柱组合壳体来模拟潜艇典型尾部结构,采用有限元(FEM)和快速多极边界元(FM-BEM)方法,研究了壳体的舱壁布置形式、激振力方向、流体介质、锥壳段刚度、壳体阻尼对其声学性能的影响。在验证了原模型的干模态基础上,分别计算了各因素对新模型辐射声功率的影响,结果表明:(1)分布轴向力作用下,采用球舱壁加强的组合壳体水下辐射声功率及效率最小;(2)由于径向力更易激起壳体的周向模态,其激起的水声要强于轴向力,但轴向力的作用也不可忽视;(3)施加径向力时,壳体在水中的轴向位移小于在空气中,而法向位移大于在空气中;(4)锥壳段刚度对降噪无明显作用,而适当增加壳体阻尼可降低声辐射。本文的研究结论可为潜艇尾部声学优化设计提供参考。 相似文献
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研究多个设备振动激励下的水中有限长圆柱壳体振动与声辐射特性。基于薄壳理论,建立单频多个设备振动激励下水中有限长圆柱壳体的声振耦合方程,采用模态展开法推导出多源激励下壳体振动响应和辐射声功率的解析表达式,分析设备激励源数、激励形式及其组合方式等对壳体振动响应和辐射声功率的影响规律。研究表明:多设备振动激励作用下,施加的多点激励力间距越大,壳体结构振速响应和辐射声功率越低;沿周向施加线激励力,不易激起壳体振动与声辐射,而沿轴向施加的激励力越集中,所激起壳体的振动与声辐射越强;在激励力合力相同的条件下,增加激励力接触面积可有效隔声。研究结果可为水下航行体的振动噪声控制提供理论依据。 相似文献
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Ⅳ型弯换能器的振动机理比较复杂,它包涵着驱动振子的振动、壳体的振动、水介质振动及它们之间相互耦合而构成的复合振动。本文对其进行了较详细的理论分析,给出了换能器壳体的振动位移分布和谐振频率。并根据干模态讨论了换能器在水中的声辐射特性;再者,结合压电方程及换能器的振速、应力分布给出了换能器在水中的电机声等效电路。理论分析结果与有限元法及实验测量进行比较,符合较好。 相似文献
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基于分层理论,建立了四边简支约束条件下薄板声辐射特性有限元分析模型,计算了其固有频率、辐射声功率及振动均方速度,并与Comsol软件计算结果进行对比,证明了该方法的有效性。其次,将分层理论用于贴敷阻尼薄板的声辐射特性研究中,分析了单/多层阻尼对结构声辐射特性的影响。最后,通过分析贴敷阻尼薄板在轻/重流体、不同流速条件下的声辐射特性,研究了流体对贴敷阻尼薄板声辐射特性的影响。结果表明,贴敷多层阻尼的薄板结构声辐射特性对阻尼材料贴敷顺序较为敏感,将弹性模量较大的阻尼材料贴敷在靠外侧能够增大约束阻尼层的剪切变形,有利于提高结构整体的损耗因子,降低结构的振动和声辐射;流体流动时,结构声振特性将发生非线性变化,当流速较低时,结构声振特性变化明显,随着流速增大,变化趋势趋于平稳。 相似文献
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复合材料四结点四边形多层退化壳单元 总被引:1,自引:0,他引:1
本文提出了一个复合材料四结点四边形多层退化壳单元。单元从修正的Hu-Washizu变分原理导出,独立假设位移场、每层内部应变场和应力场。文中给出了几个复合材料板和壳静力线性问题实例。计算结果表明本文的单元是准确和有效的。 相似文献
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A co-rotational 8-node assumed strain shell element for postbuckling analysis of laminated composite plates and shells 总被引:2,自引:1,他引:1
The formulation of a nonlinear composite shell element is presented for the solution of stability problems of composite plates
and shells. The formulation of the geometrical stiffness presented here is exactly defined on the midsurface and is efficient
for analyzing stability problems of thin and thick laminated plates and shells by incorporating bending moment and transverse
shear resultant forces. The composite element is free of both membrane and shear locking behaviour by using the assumed natural
strain method such that the element performs very well as thin shells. The transverse shear stiffness is defined by an equilibrium
approach instead of using the shear correction factor. The proposed formulation is computationally efficient and the test
results showed good agreement. In addition the effect of the viscoelastic material is investigated on the postbuckling behaviour
of laminated composite shells.
Received: 6 February 2002 / Accecpted: 6 January 2003
ID=" Present address: School of Civil Engineering, Asian Institute of Technology 相似文献
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《Composites Part B》2001,32(3):237-247
The bending, buckling and free vibration problems of non-homogeneous composite laminated cylindrical shells are considered. Hamilton–Reissner's mixed variational principle is used to deduce a consistent first-order theory of composite laminated cylindrical shells with non-homogeneous elastic properties. The governing equations with their required boundary conditions are derived without introducing any shear correction factors. Numerical results for the transverse deflections, stresses, natural frequencies and critical buckling loads are presented to show the advantages of this theory. The influences of the non-homogeneity and thickness ratio on the shell structural response are investigated. The study concludes that the inclusion of the non-homogeneity effect is required, even if it is weak, for predicting the actual structural response of the shells. 相似文献
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本文从剖析单元构成因素的角度出发,综合评述了目前用于复合材料板壳结构分析的各种有限单元,分析了这些单元的特点及其适用范围,并说明Mindlin类等参板壳单元广泛应用迭层板壳的原因以及存在问题、解决办法。还深入地讨论了杂交单元应用至迭层板壳计算的优点。 相似文献
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The paper investigates the buckling behaviour of anisogrid composite lattice cylindrical shells under axial compression, transverse bending, pure bending, and torsion. The lattice shells are modelled as three-dimensional frame structures composed of curvilinear ribs subjected to the tension/compression, bending in two planes and torsion. The specialised finite-element model generation procedure (model generator/design modeller) is developed to control the orientation of the beam elements allowing the original twisted geometry of the curvilinear ribs to be closely approximated. The effects of varying the length of the shells, the number of helical ribs and the angles of their orientation on the buckling behaviour of lattice structures are examined using parametric analyses. Buckling of the lattice shells with cutouts is also analysed. The results of these studies indicate that the modelling approach presented in this work can be successfully applied to the solution of design problems. 相似文献