Dynamic Analysis of a Spinning Laminated Composite-Material Shaft Using the hp-version of the Finite Element Method

Boukhalfa, Abdelkrim

doi:10.5772/15676

Cited by 1 publication

(2 citation statements)

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“…Moreover, it is worth noting that remarkable differences exist between the first natural frequencies of Ref. [28] and those obtained with the other approaches, especially for 6 equal to 15 deg, 30 deg, 45 deg, and 60 deg. The use of a constant shear correction factor could be the reason for these important discrepancies, since the shear effects are closely related to the lamination scheme.…”

Section: Rotordynamics Equations In Cuf Formmentioning

confidence: 93%

“…In order to show the accuracy of the CUF elements, natu ral frequencies of the boron-epoxy shaft (Table 1), computed with TE elements, are listed in Table 5 and compared with the results found in Ref. [28], where a first-order shear beam theory with a torsion function was conceived, and with those obtained using Di.Qu. M.A.S.P.A.B.…”

Section: Rotordynamics Equations In Cuf Formmentioning

confidence: 99%

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Variable Kinematic One-Dimensional Finite Elements for the Analysis of Rotors Made of Composite Materials

Carrera

Filippi

2014

Journal of Engineering for Gas Turbines and Power

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This paper deals with the dynamic response o f rotors made o f anisotropic, laminated composite materials. It is a sequel to the authors' previous work, which was devoted to the rotordynamics o f metallic structures. The used variable kinematic one-dimensional models describe any cross-sectional deformation o f the rotor and go beyond the plane strain assumptions o f classical Euler-Bernoulli and Timoshenko beam theories. Refined theories are obtained by applying the Carrera unified formulation, which is extended here to the rotordynamics o f multilayered composites. The displacement variables over the rotor cross section x-z plane are approximated by x,z polynomials o f any order N. Thin-walled cylindrical shafts and boxes are analyzed. These structures are made o f uni directional layers, whose fiber orientation can vary with respect to the rotor-axis as well as in the x-z plane. Several analyses have been carried out to determine the vibrational response as a function o f the rotating speed. Classical beam theories are obtained as par ticular cases and results available in the literature, including shell results, are used to assess the presented theory. The proposed refined models are very effective in investigat ing the dynamic behavior o f laminated composite rotors. I n t r o d u c t io nIt is well known that composite materials present excellent me chanical properties, such as high specific stiffness and strength, ease of formability, a wide range of operating temperatures, and many others. These properties justify their extensive use in many applications, among which the design of rotors, whose dynamic behavior is worthy of study. For example, interesting experiments were carried out in Refs. [1-3] on either graphite or boron/ epoxy shafts. The advantages of orthotropic materials over their isotropic counterparts were pointed out, and useful references were provided for analytical formulations. Despite their limita tions, classical beam theories have been extensively used to inves tigate the critical speeds and instabilities of composite shafts. For instance, with the purpose of proposing an optimization algorithm to define the best lamination scheme, a first shear deformation theory, including the rotatory inertia, was used in Ref.[4], The optimization was direct in order to maximize the first bending fre quency, thus ensuring a sufficient torsional strength by imposing that the lamination angle of a certain number of plies was equal to 45 deg. Later, Bert and Kim developed one-dimensional models, based on Euler-Bemoulli [5] and Bresse-Timoshenko [6] theo ries, which included bending-twisting coupling. The critical speeds were in good agreement with the results obtained through both shell and experimental approaches. Naturally, when shear effects become important, the Euler-Bernoulli theory does not lead to accurate results. In Ref.[7], Chen and Peng investigated the stability of composite spinning cylinders subjected to com pressive loads using the Timoshenko model and the equivalent modulus beam theory...

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Section: Rotordynamics Equations In Cuf Formmentioning

confidence: 93%

Section: Rotordynamics Equations In Cuf Formmentioning

confidence: 99%