Damage detection for laminated composites using full-field digital image correlation

Abstract

Laminated composites are complex multifunctional materials and often endure barely visible damage which is characterised by matrix cracks and fiber damage leading to delamination. These composites are often used in safety-critical industries such as aeronautical and automotive industries which makes it crucial to have techniques to assess damage before and during use. This paper presents full-field digital image correlation (DIC) as a method for damage detection in laminated composites under static loading conditions. Full-field DIC is an optical measuring system used to assess deformation data (i.e. displacement and strain) in any component under various loading conditions. Assuming that the damage changes the mechanical properties, the method is applied here to detect changes in stiffness caused by barely visible impact damage in laminated composites. It is shown in the experimental findings that full-field DIC has the capability to detect barely visible damage caused by various impact energies in laminated composites, provided that the excitation or form of loading is applied near the impacted area.