Impact damage in aerospace structures: Investigating the impact characteristics of different standard aerospace grades of glass fibre reinforced aluminium laminate (GLARE®)

Abstract

The invention of Fibre Metal Laminate (FML) was a major breakthrough in the aerospace and the material world. The idea of combining monolithic sheets of metal with the fibre-reinforced polymer brought around multiple advantages over metallic materials offering much lower density and superior strength which paved its way towards lightweight structural applications. These fibre metal laminates also come about with an unparalleled advantage of superior fatigue life, excellent strength-to-weight ratio, and extraordinary damage tolerance in comparison to the conventionally used monolithic materials. This made it a strong material candidate for aerospace structures, eventually leading to its application as a fuselage skin on modern aircraft for e.g., GLARE on Airbus A380. However, these structures are prone to impact-related events such as bird strikes, hailstorms, lightning strikes and even impacts by ground service equipment which could be detrimental to the structural health of the aircraft and could pose a serious concern towards the aircraft’s safety. This research work investigates the assessment of the impact damage resulting from different impact energies in different standard aerospace grades of GLARE FMLs. For the investigation, GLARE 3 and GLARE 5 grades with different layup configurations were used. The impact damage characteristics are investigated using X-ray computer tomography highlighting the differences observed in the damage morphology corresponding to the impact parameters and the impacted GLARE configuration. The impacted GLARE plates are further investigated with the C-scans for the assessment of the induced damage at different impact energies. Additionally, the findings from the X-ray tomography are correlated and validated with the findings of the C-scans.