Optimum shapes for minimising bond stress in scarf repairs

Abstract

Bonded scarf repairs are used in composite structures when high strength recovery is needed or when there is a requirement for a flush surface to satisfy aerodynamic or stealth requirements. However, scarf repairs are complex to design and require the removal of significant parent structure, particularly for thick skins. In this investigation, analytical and numerical approaches have been developed to investigate whether an optimum repair shape for a known biaxial load can be determined. The results clearly demonstrate that the strength of a repaired panel can be improved by optimising both the initial damage cut-out shape and the scarf angle distribution.

Keywords:

• Composite materials
• optimum shapes
• scarf repairs.

Additional information

Notes on contributors

C H Wang

Dr Chun Hui Wang is currently a Principal Research Scientist and the Head of the Advanced Composite Technologies in the Air Vehicles Division, Defence Science and Technology Organisation. After completing his PhD study at the University of Sheffield, UK, in 1990, he worked at the University of Sheffield, the University of Sydney, and Deakin University, Australia. His main research experience is in the areas of advanced composite structures, bonded repairs, electromagnetic wave scattering and imaging, fatigue, and fracture mechanics.

A J Gunnion

Dr Andrew Gunnion is a research engineer at the CRC-ACS, where he is currently working in several research fields including bird-strike analysis, crash simulation of composite joints and repair methods for composite structures. After successfully completing his PhD, Andrew continued to work with Airbus and CRC-ACS as an RMIT research fellow until joining the CRC-ACS in 2005.