Optimum alternate material selection methodology for an aircraft skin

Abstract

Weight penalty has been a challenge for design engineers of aerospace vehicles. Today’s high-efficiency combat aircraft undergoes intense stress and strain during flying missions, which require stronger and stiffer materials to retain structural integrity. Though metallic materials have been successfully used for the construction of aircraft structures and components, metals still have a low strength-to-weight ratio. This paper aims to develop an alternate optimised material selection methodology to replace the metallic skin of a medium-sized military aircraft. The search for the optimum material will result in reduced aircraft weight which will be benefitted by extra payload on the aircraft. The selection methodology is comprised of finding design pressure limits on the aircraft skin, and comparison of properties (strength, elastic modulus, shear modulus, etc.) and performance (safety factor, deflection, and stress) of the existing metallic skin with alternate optimised material. The comparison was made under aerodynamic pressure, bending force, and twisting moment. Carbon Fibre Reinforced Polymer/Epoxy (CFRP) Uni-Directional (UD) prepreg (elastic modolus is 209 GPa) was selected as an alternate optimum material to replace the aluminium alloy skin of the aircraft studied. The selected alternate optimum material resulted in the reduction of aircraft skin weight by 30%.