Experimental study on delamination identification in tapered laminated composite plates using damage detection models

Abstract

Delamination frequently occurs in composite laminates composed of fibre-reinforced polymer (FRP) and is considered a typical type of failure. The structural health monitoring (SHM) of structures with composites can be assessed by utilising changes in dynamic responses caused by a reduction in structural stiffness resulting from delamination. However, to ensure successful SHM, an inverse problem solution is required. Solving inverse problems can be computationally expensive and time-consuming, especially for large and complex structures. This study examined the efficiency of different damage identification techniques in detecting delamination in tapered composite plates. Four damage detection algorithms were tested, including the mode shape curvature (MSC), gapped smoothing method (GSM), mode shape curvature square (MSCS), and the gapped smoothing method square (GSMS) were implemented as damage index (DI) and curvature damage factor (CDF). A tapered composite plate composed of glass-fibre reinforced polymer was subjected to experimental modal analysis, including one undelaminated plate and three artificially delaminated plates. The delamination areas in the artificially damaged composite plates ranged from 1.5% to 8% of the plate area and were located at different interfaces. The results showed that statistical treatment further enhanced the damage identification, the CDF using the GSMS method performed the best overall, particularly in identifying the size and locations of delamination. The study also found that adding more modes to the averaging process increased CDF sensitivity and reduced uncertainty. This study suggests that the CDF method using GSMS is a promising approach for detecting delamination in tapered composite plates, with potential applications in aerospace, automotive, and civil engineering.