Design and fabrication of a helicopter unitized structure using resin transfer moulding

We present the numerical and experimental studies for the design of a novel unitized configuration for the manufacture of a three-dimensional aerodynamic beanie using resin transfer moulding (RTM). The beanie is a component with complex closed-shell geometry, which is traditionally manufactured using autoclave processes that require several bonding steps during production. In our work we use a multidisciplinary approach to fabricate the component not through a succession of steps but rather integrating design and manufacturing into the realization of a pre-industrial RTM prototype, with significant reduction of the production time. The new RTM-based design has several advantages in terms of reduced manufacturing cost and enhanced mechanical properties. A bird impact analysis was performed to investigate the structural behaviour of the unitized solution. The peak contact pressure during the bird strike is reduced, as well as the maximum vertical displacement. At the same time, the total weight of the structure is reduced by approximately 26% and the production time of 47% with respect to prepreg manufacturing processes. Mechanical tests performed on the manufactured RTM-based prototype also show that the interlaminar shear strength is improved by 70% with respect to the prepreg-based ones.