Nonlinear First Ply Failure Response of Composite Cylindrical Shells under Non-Uniform Transverse Pressure

Abstract

Use of laminated composite materials in place of conventional materials in weight sensitive disciplines of engineering including structural engineering started from the second half of the twentieth century. Confident use of composite structural units necessitates comprehensive understanding of the material behaviour including failure characteristics which the researchers are focusing on in the recent papers. Failure in composite materials may initiate from the surface and from inner laminae as well which may remain undetected. Unnoticed flaw may progress leading to overall failure of the structural unit. This paper intends to explore the first ply failure characteristics of shells and takes up the industrially popular cylindrical configuration having wide industrial applications about which only a very few papers report the failure related information. Failure of clamped graphite-epoxy shells is studied using Sanders' linear strains together with von-Kármán nonlinear strain components. The shells subjected to nonuniform sinusoidal is modelled using isoparametric Serendipity element having five degrees of freedom at each node. The paper reports the gross failure behaviour of a number of shell options with varying lamination and curvature. The results are presented systematically for lucid understanding and are interpreted from practical engineering standpoints. The paper concludes with pin pointed guidelines based on which the different shell combinations may be taken up for relative performance study.