NDI Tool for Heat Damage Detection in Composites

ABSTRACT: Incipient thermal damage (ITD) of carbon fiber reinforced plastic (CFRP) composites cannot be detected by common nondestructive evaluation (NDE) methods, such as ultrasound or visual inspection.ITD, however, can reduce matrix dominated mechanical properties of composites and thus requires detection and evaluation to ensure the integrity of composite structures that may be subjected to thermal exposures.Fourier transform infrared (FTIR) spectroscopy is an established technique that has shown promise for NDE of ITD.The purpose of this work is to develop methodologies using FTIR to detect thermal damage of BMI carbon fiber reinforced composite with ITD.: The FTIR works by measuring chemical changes to the polymer matrix as a function of the time and temperature of exposure, which can be correlated with matrix dominated mechanical properties such as short-beam strength (SBS). A model that uses FTIR spectra to predict the level of damage based on the FTIR measurements will be developed. Additionally, a complementary technique of using Fringing Electric Field Dielectrometry sensors will be integrated with FTIR scans in order to achieve an unprecedented diagnostics capabilitybeing able to combine sensor signals from the surface and from the bulk of the material for a comprehensive damage evaluation.; BENEFIT: The proposed project will advance progress towards a powerful and versatile non-destructive sensing technology widely applicable to aircraft technology as well as naval and automotive fields, as composite materials are used increasingly commonly in these fields.This approach offers several advantages over current NDE, including more sensitive detection of incipient thermal damage. Successful development of the proposed methodology maylead to the determination of depth of damage, as well as surface damage.