Low velocity and high velocity impact of composites and fibre metal laminates for commercial aircraft structures

Abstract

Fibre Reinforced Polymer (FRPs) and Fibre Metal Laminates (FMLs) are gradually replacing the conventional metallic materials from fabricating the primary structures of modern passenger aircraft due to their brilliant properties, for example, excellent strength-to-weight ratio. However, its isotropic characteristics might make associated structures perform complicated failure mechanisms under impact loading. Therefore, a better understanding of this mechanism is urgent for its widespread application in the aviation industry. Driven by this, a series of impact tests with various impact velocities were carried out in this project. The Unidirectional (UD) Carbon Fibre Reinforced Polymers (CFRPs) were tested under the drop-weight tower, in which impactors with different geometries were employed. Damage details were acquired by C-scanning, White light Interferometry (WLI), Scanning Electron Microscopy (SEM), and Optical Microscopy (OM). It was demonstrated that impactor geometry has a considerable influence on the dynamic response and damage behaviour of CFRP panels under low-velocity impact. Furthermore, woven fabric CFRP and Glass Fibre Reinforced Polymer (GFRP) panels with different dimensions, and the FMLs combined with aluminium plates and woven GFRPs were tested for their ballistic impact performance by employing the gas-gun facility. Panels' out-of-plane displacement during the impact events was recorded in detail via the Three-dimensional (3D) Digital Image Correlation (DIC) implemented by a couple of high-speed cameras. In particular, the oblique high-velocity impacts were conducted to investigate the differences between oblique and normal impacts. Results show that target dimensions, impact energy and impact angles significantly affect these materials' ballistic impact performance.