Use of composite and sandwich materials in complex shell structures

Composite and sandwich shell sections can be of use in a variety of structures including rail cars, truck tanks, aircraft fuselage etc. It is important to study the behavior of these shell sections so that they can be exploited to the fullest possible extent. The present study presents solutions for different cases of shell and ring sections and a shell of variable cross section and also compares the behavior of composite and sandwich materials with other conventional materials.;Both exact and energy solutions are developed for ring sections of symmetric as well as asymmetric composite and sandwich materials under constant internal pressure. The governing equations obtained by applying variational calculus to the potential energy function are solved to obtain the general solution for ring sections. The constants can be evaluated for the boundary condition considered giving the exact solutions. Solutions for simply supported boundary conditions are presented. The energy solutions are obtained by minimizing the potential energy function expressed in terms of selected displacement functions. The comparison of the two solutions validates these trial functions. Comparisons of behavior of a few materials are also presented.;Energy solutions are developed for axi-symmetric circular cylindrical shells made of asymmetric composite sandwich construction under constant internal pressure with edges simply supported. The trial functions are verified against exact solutions available in the case of isotropic and symmetric composite materials. Energy solutions are then developed for shell sections with constant internal pressure for four different boundary conditions. Results for different materials are presented.;Solutions are then derived for a shell of variable cross section, having flat sides and curved corners, for constant internal pressure and liquid pressure. The ends are simply supported. The solutions obtained through piece-wise matching of ring and beam sections are verified with solutions for circular cross section by letting the lengths of the flat sides be zero. Based on the solutions, an optimum cross section is suggested for maximizing the internal volume to structural weight ratio, and the superiority of sandwich construction in providing higher weight savings is demonstrated.