Flexural response of spoolable composite tubulars: an integrated experimental and computational assessment

This study is focused on the structural behavior of filament-wound composite tubes which are stored on large spools for ease of storage, handling, and installation. The objective is to identify the minimum spool radius without introducing damage in the composite tube during storage. Experimental and computational studies are undertaken to assess the influence of different material systems, layups, and tube geometry on the stress-strain response induced in bending. Four-point flexure tests are conducted to simulate the spooling conditions where angle-ply asymmetric glass and carbon polymeric-matrix composite tubes with various lay-up and radius/ thickness ratios are loaded until failure. Finite element models of these tests are analyzed with the ABAQUS package utilizing two-dimensional S8R shell elements. The models incorporate non-linear geometry effects as well as a material subroutine (UMAT) to detect progressive damage details, that is, to predict damage initiation and its progression. Residual stresses from processing are also incorporated to provide a realistic foundation for progressive damage calculations. The moment-curvature response using maximum stress, Hashin-Rotem, and Hashin damage criteria are compared with experimental data. The models are used to conduct parametric studies of the effects of lay-up, geometry, and constitutive material on the flexural behavior of the composite tubes. (C) 2004 Elsevier Ltd. All rights reserved.