Ground vehicle blunt impact damage formation to composite aircraft structures

Abstract

Composite aircraft structures such as fuselage and wings are subject to impact from many sources. Of particular interest are impacts which can impart severe damage that is difficult to visually detect, or is even not visually detectable. Such damage modes include delamination, separation/delamination of stringers and stiffeners from skin, and fracture of internal stiffening components such as stringers and frames. Extensive damage can be produced by blunt impact sources involving wide-area contact, which reduces the propensity to leave visible signs that damage has formed, especially with high-strength composite outer skin. Ground service equipment (GSE) is a realistic and oft-occurring source of blunt impact damage due to: (i) the interactions between GSE and aircraft typically involving a soft rubber bumper material, (ii) the close proximity with which GSE operate around aircraft, and (iii) the high mass of GSE involves very large impacting energies despite their slow speeds. Blunt impact damage can produce both local and non-local damage since, as the contact area increases, higher energy levels are involved for blunt impact damage to occur. Therefore, inspections to find damage from GSE impact events require that locations relatively far away from the impact sites must also be inspected.