Modification of the linear theory of lamination
Andrzej P. Wilczyński Politechnika Warszawska, Instytut Mechaniki i Konstrukcji, ul. Narbutta 85, 02-524 Warszawa
Annals 4 No. 10, 2004 pages 184-188
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abstract This is an improved and shortened version of the Authors lecture at the IV School of Composites, held at Wisła on 8-10 December, 2003. The theory of lamination, known sometimes as meso-mechanics of composites is dealing with prediction of properties of multi-layered composites, providing means for their practical applications. In the case of fibrous, polymeric laminates for this purpose usually the classical, linear theory of plates is employed, basing on the fact, that composite structures in general are constructed as thin-walled plates and shells. In such a case the results are greatly simplified in comparison with non-linear theories, while introduced in this way discrepancies are mostly of no significance. The final effect of application of the theory of lamination is providing global constitutive equations for the laminate and means for calculations of local stresses in particular layers. Some time ago the paper [3] gave an inspiration for forming a new, linear theory of lamination, based not on response to curvatures of the layers but their mean angle of deflection, taking into account values resulting from inter-laminar shear. The derivation of the theory, presented in this paper allows for calculation and inclusion of shear stresses into strength and safety factor calculations, better understanding of the problems of lamination and a tool for more accurate determination of laminate deflections. Key words: lamination, composites, constitutive equations, shear stress influence