Global and local area inspection methods in damage detection of carbon fiber composite structures

Abstract

The paper presents multiple impact damage detections and characterization in a multi-layered carbon fiber reinforced polymer structure using a multi-step combination of the global area and local area damage detection methods. A global area analysis using laser Doppler vibrometer (LDV) with piezoelectric lead zirconate titanate (PZT) actuator-based guided waves (GW) excitation was used to detect and locate the damage. The GW full wavefield (FWF) mode conversion and root mean square (RMS) based LDV studies helped to visualize the impact crack damage (ICD) when tested at varying excitation frequencies. The experimental results were cross-verified numerically using the spectral element method (SEM). The implemented structural health monitoring (SHM) based sectorial elliptical code (SEC) reduced the overall calculation time in damage localization and accurately identified the damage from experimental and numerical data. An infrared thermography (IRT)-based crack identification algorithm was developed in pinpointing the ICD shape. The automatic method removes the influence of high heat sources and highlights the damage zones easily. The accuracy of the localization strategy was successfully verified with non-contact active IRT analysis. The crack size and damage severity were quantified using the ultraviolet radiation (UVR) method with a solution mixture based organic dye. The global area method allows detecting possible damage, validated and quantified with the non-destructive testing (NDT) techniques.