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CivilComp Proceedings
ISSN 17593433 CCP: 79
PROCEEDINGS OF THE SEVENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and C.A. Mota Soares
Paper 28
Modelling CrossPly Laminated Elastic Shells by a HigherOrder Theory and Multiquadrics A.J.M. Ferreira, C.M.C. Roque and R.M.N. Jorge
Department of Mechanical Engineering and Industrial Management, Faculty of Engineering, University of Porto, Portugal A.J.M. Ferreira, C.M.C. Roque, R.M.N. Jorge, "Modelling CrossPly Laminated Elastic Shells by a HigherOrder Theory and Multiquadrics", in B.H.V. Topping, C.A. Mota Soares, (Editors), "Proceedings of the Seventh International Conference on Computational Structures Technology", CivilComp Press, Stirlingshire, UK, Paper 28, 2004. doi:10.4203/ccp.79.28
Keywords: composite shells, multiquadrics, higherorder theory.
Summary
Classical theories developed for thin elastic shells are mostly based on the LoveKirchhoff assumptions. This theory considers that straight lines normal to the undeformed middle surface remain straight and normal to the deformed middle surface; that the normal stresses perpendicular to the middle surface can be neglected in the stressstrain relations and the transverse displacement is independent of the thickness coordinate. Therefore transverse shear strains are neglected as reported in surveys of classical shell theories by Naghdi [2] and Bert [3,4]. These theories are expected to produce accurate results when the sideto thickness ratio is large or when material anisotropy is low. The application of such theories to thick or moderately thick or laminated composite shells can lead to serious errors in terms of deflection or stresses.
The introduction of transverse shear and normal stresses represent an improvement to classical theories. However, for (side to radius ratio) the transverse normal stresses are negligible when compared to the transverse shear stresses. The effect of transverse shear and normal stresses in shells studied by Hildebrand et al [5], Lure [6] and Reissner [7]. The effect of transverse shear deformation was also considered by Vinson [8], Dong et al [9,10] and Whitney and Sun [11,12]. Reddy [1] presented a higherorder theory that is based on five degrees of freedom (same number as in a firstorder shear deformation theory by Reddy [13]). This theory assumes a constant transverse deflection through the thickness and the displacements of the middle surface are expanded as cubic functions of the thickness coordinate. The displacement field leads to parabolic distribution of the transverse shear distribution of the transverse shear stresses and zero transverse normal strain. Therefore no shear correction factors are used. In Reddy [1] a Naviertype solution is presented. This solution is only feasible for special loading and boundary conditions. The solution of laminated composite shells by finite elements has been the subject of intense research. The analysis of laminated composite shells by meshless methods is still starting. The purpose of the present research is to demonstrate that a truly meshless method such as the multiquadric radial basis function method can be successful in the analysis of laminated composite shells. The multiquadric radial basis function method was introduced by Hardy [14] for the interpolation of scattered geographical data. The use of multiquadrics for the solution of partial differential equations was first proposed by Kansa [15,16]. The authors have used the method for the solution of laminated beams and plates in bending. The solution of laminated elastic shells in bending by multiquadrics is here performed. References
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