First ply failure study of composite conoidal shells used as roofing units in civil engineering

In practical civil engineering, the necessity of covering large column free open areas with shell surfaces is often an issue. Such areas in medicinal plants and automobile industries prefer entry of north light through the roofing units. Doubly curved singly ruled conoidal shells are stiff and easy to fabricate as surfaces and fit excellently to the above-mentioned industrial requirements. Today, the engineers intend to use laminated composites to fabricate these shell forms. Engineers are also concerned with the performance evaluation of different stacking sequences to maximize the stiffness for a given quantity of material consumption. First ply failure load analysis of composite plates appears abundantly in the literature, but on composite shells, only a few papers are found (though not on conoidal shells). This paper addresses an important issue with which the practical engineers are often concerned regarding performance evaluation of different laminations (including antisymmetric and symmetric cross and angle plies) in terms of first ply failure load of composite conoids. The paper uses the finite element method as the mathematical tool and concludes logically to a set of inferences of practical engineering significance. © 2013 ASM International.