Monitoring Damage Development Around Stress Raisers in Carbon/Epoxy Laminates

摘要

An experimental and numerical investigation was carried out for the feasibility of determining damage development in carbon/epoxy composite laminates with a circular hole. The study involved flash thermography to map the damaged region in these specimens. First, thermographic response of implanted delaminations in composite laminates was examined using both numerical and experimental approaches. Next, damage development around a circular hole in a composite specimen was examined using thermography. The specimen was cyclically loaded until fracture to generate different levels of damage near the center of the specimen. Thermographic images of damage development at different fractions of fatigue life were recorded. Numerical models of thermal response of the region with evolving damage were also examined to assess the effectiveness of flash thermography under different conditions. The carbon/epoxy composite laminate was pulsed and examined using laser vibrometry in order to characterize the modes of stress wave propagation. Numerical simulations of a similarly excited carbon/epoxy panel were carried out as well.