Digital image correlation analysis applied to monitor damage evolution of composite plates with stress concentrations and bonded patch repairs

The use of composite materials in aircraft industry has risen significantly in recent years. During its service life, an aircraft is subjected to several structural and aerodynamic loads. These loads can cause damage or weakening of the structure that may affect its load carrying capabilities. The restoration of structural efficacy by repair or reinforcement of the damaged or weakened part to assure continued airworthiness of an aircraft has thus become an important issue in recent years. In this work, the behaviour of scarf-type bonded patches in laminate composites are monitored using full-field measurement methods based on Digital Image Correlation (DIC) techniques. Damage evolution of the repaired area under tensile loading was recorded from DIC and a Lamb wave based technique. These results were compared with X-radiographs and C-scan in order to identify damage after loading.