Project title: Effect of Through-thickness Stitching on the Interlaminar Fracture Toughness of High Performance Composites Under Dynamic Loading

Advanced fibre-reinforced composites have very attractive mechanical properties. Combined with their light-weight nature, they have been used in a large number of high performance applications, such as aerospace, automobile, marine, medical, and sport equipment. In order for the composites to achieve the highest performance, the fibres will be continuous, and the composite will be laminated. With such a laminated structure, and a high degree of anisotropy existing within each ply, advanced composites are susceptible to delamination damage, especially under impact conditions.

Delamination damage and its growth under dynamic loading are of major concern in the application of advanced fibre, especially carbon-fibre-, epoxy matrices composites. Through-thickness stitching is one of the most effective techniques that can improve the delamination resistance of composite laminates commonly used in aircraft, marine and other transportation structures. Despite the many advances made in recent years by many investigators (including us), there are still some unresolved basic issues, especially under high velocity impact loading such as experienced in collisions, which need further investigation. In this project, the split Hopkinson pressure bar technique will be used to determine the interlaminar fracture toughness of stitched glass and carbon fibre reinforced composites under dynamic loading. The toughening mechanisms will be studied using optical and electron microscopy and analytic models developed to investigate the constraint effect and the effectiveness of the stitches with varying stitching parameters.

Supervisor: Prof Robert K Y Li (aprkyl@cityu.edu.hk)

Suitable for: M.Phil./Ph.D.