Diagnosis of Delaminated Composites Using Post-processed Strain Measurements under Impact Loading

Potentially having a destructive influence on the mechanical properties of composite laminates, the invisible phenomenon of delamination frequently occurs under impact loading. In the present study, simulating the performance of long-gauge fiber Bragg grating sensors, impact-induced average strains within laminated composites are utilized to develop a delamination identification technique. First, strain-based modal parameters are extracted from the estimator of frequency response functions using two different approaches. Next, these parameters are employed in various damage detection indicators. Then, the presence, location, and severity of delamination introduced at locations with the least effect on modal changes are detected. The results of different numerical examples with various delamination sizes and positions elucidate the considerable efficiency of average-strain measurements to diagnose delaminated composites.