共查询到20条相似文献,搜索用时 0 毫秒
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A semi-analytical annular finite element is developed for the dynamic analysis of non-rotating, rotating or pre-stressed discs having varying thickness in the radial direction. The element is based on the Mindlin thick plate theory. It has 2 nodes, 12 degrees of freedom, parabolic thickness, and is capable of representing all the geometric and natural boundary conditions of thick plates. The element is applied to the dynamic analysis of non-rotating and rotating uniform discs, and to practical turbine discs. The predicted natural frequencies of the discs are compared with analytical, experimental and other finite element solutions. 相似文献
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The coupled vibration modes of a rotating blade-disc system are calculated by a finite element method. It is assumed that a large number of identical blades are present, such that the resulting blade loadings on the disc can be considered continuously distributed around the rim of the disc. The disc may have arbitrary profile, and the blades may be tapered and twisted, thus closely representing practical axial flow turbomachine configurations. The effects of rotation, thermal stress, and transverse shear and rotatory inertia in discs of moderately thick profile are readily incorporated into the finite element model. Calculated values of frequencies are compared with experimental data obtained on non-rotating models, and the convergence of the solution is examined by comparison with exact solutions, which can be obtained for configurations of simple geometry. Excellent agreement with experimental data is obtained when using remarkably few elements in the mathematical model, and convergence of the solution is extremely rapid. 相似文献
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Dynamics behavior of rotating bladed discs: A finite element formulation for the study of second and higher order harmonics 总被引:1,自引:0,他引:1
Annular finite elements for the computation of second and higher order harmonics modes of bladed rotating discs are developed. The elements take into account gyroscopic effect and stiffening due to centrifugal and thermal stresses (the latter not present in arrays of blades). The displacement field is expressed by a truncated Fourier series along the angle and by polynomial shape functions in the radial direction. This paper is the generalization of a previous study limited to zero- and first-order harmonics and deals only with second and higher order harmonics modes that are uncoupled from the modes involving the behavior of the rotor as a whole. Several cases have been studied to verify the accuracy of the disc and array of blades elements. 相似文献
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Abstract An accurate vector finite element solution of the nonsynchronous directional coupler problem is presented, illustrating coupling lengths and supermodes of the complete structures. 相似文献
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An accurate vector finite element solution of the nonsynchronous directional coupler problem is presented, illustrating coupling lengths and supermodes of the complete structures. 相似文献
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This paper presents numerical and experimental validation of results obtained by a shell finite element, which has been developed for modeling of the dynamic behavior of sandwich multilayered structures with a viscoelastic core. The proposed shell finite element is very easy to implement in existing finite element solvers, since it uses only the displacements as degrees of freedom at external faces and at inter-layer interfaces. The displacement field is linearly interpolated in the thickness direction of each layer, and analytical integration is made in the thickness direction in order to avoid meshing of each sandwich layer by solid elements. Only the two dimensional mid-surface of reference is meshed, facilitating the mesh generation task. A simplified modal approach using a real modal basis is also proposed to efficiently calculate the dynamic response of the sandwich structure. The proposed method reduces the memory size and computing time and takes into account the frequency-dependence of the polymer core mechanical properties. Results obtained by the proposed element in conjunction with the simplified modal method have been numerically and experimentally validated by comparison to results obtained by commercial software codes (MSC/nastran and ESI/rayon-vtm), and to measurements done on automobile windscreens. 相似文献
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This paper investigates the frequency dependent viscoelastic dynamics of a multifunctional composite structure from finite element analysis and experimental validation. The frequency-dependent behavior of the stiffness and damping of a viscoelastic material directly affects the system's modal frequencies and damping, and results in complex vibration modes and differences in the relative phase of vibration. A second order three parameter Golla–Hughes–McTavish (GHM) method and a second order three fields Anelastic Displacement Fields (ADF) approach are used to implement the viscoelastic material model, enabling the straightforward development of time domain and frequency domain finite elements, and describing the frequency dependent viscoelastic behavior. Considering the parameter identification a strategy to estimate the fractional order of the time derivative and the relaxation time is outlined. Agreement between the curve fits using both the GHM and ADF and experiment is within 0.001 percent error. Continuing efforts are addressing the material modulus comparison of the GHM and the ADF model. There may be a theoretical difference between viscoelastic degrees of freedom at nodes and elements, but their numerical results are very close to each other in the specific frequency range of interest. With identified model parameters, numerical simulation is carried out to predict the damping behavior in its first two vibration modes. The experimental testing on the layered composite beam validates the numerical predication. Experimental results also show that elastic modulus measured from dynamic response yields more accurate results than static measurement, such as tensile testing, especially for elastomers. 相似文献
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为了分析两个相同的细胞在不同距离下光声信号的特性,对细胞及环境进行了有限元分析。创建了不同距离的双细胞模型和相同环境下的单细胞模型,通过双细胞模型,得到了主体细胞在受到不同距离的另一个细胞的影响下,其不同角度的频域声压级曲线。通过单细胞模型,得到了单个细胞未受到影响时,其不同角度的频域声压级曲线。将主体细胞与单细胞频域声压级曲线进行相似度比较。结果表明,在受到不同距离的细胞影响下,主体细胞各角度的频域声压级曲线,存在与单细胞相似度极高的曲线,且距离为26.6微米时,相似度最高。这项研究表明,在两个双凹形红细胞距离适当时,细胞间的光声信号相互影响最小。 相似文献
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磁体支撑结构是国际热核聚变实验反应堆(ITER)的重要部件,对其进行力学特性分析研究是确保整个反应堆正常运行的关键。通过对磁体支撑结构各工况下的强度、刚度的数值分析,给出了磁体支撑结构对应工况下各零部件的应力分布及变形量;分析结果表明磁体支撑结构各零部件的最大应力值均小于许用应力,满足强度要求,各零部件变形合理,不会出现脱开失稳现象。通过数值分析,为国际热核反应堆磁体支撑结构提供了理论设计数据,提升了磁体支撑结构的安全性和可靠性。 相似文献