Physics Based Data Reconciliation of FTIR Data for Retrieval of BMI Composite Heat Damage State

ABSTRACT: Composite materials in aircraft are susceptible to heat damage.There is an urgent need to detect and quantify heat damage at an early stage (incipient heat damage) using non-destructive methods.Handheld Fourier-transform infrared (FTIR) instruments represent a promising means to detect and quantify heat damage.Spectral Sciences, Inc. together with Aurora Flight Sciences propose a systematic acquisition of FTIR spectra from composites with varying degrees of heat damage coupled with a physics-based post-processing of those spectra.The Infrared Non-destructive Spectral Procedure for Composite Testing (INSPCT) approach will relate physically and chemically meaningful interpretations of FTIR spectra to mechanical strength and heat-damage state of the material. The key enabling technologies are the application of sophisticated retrieval and spectral abundance analyses of measured FTIR spectra and physics-based interpretation techniques based in fundamental optical properties to extract spectral fingerprints of heat damage from the signal.The product will take measured FTIR spectra and return the damage state referenced to ASTM tests.; BENEFIT: The successful product will interpret spectral features of BMI composite material measured with a handheld FTIR and relate it to ASTM test-referenced local material strength.The underlying database of FTIR measurements and ASTM-referenced local strengths will also be available as a product.A software module embedded in the handheld FTIR processor will provide the inspector prompt readings of the extent if any of heat damage to the composite.The approach we take should be adaptable to any composite material system, so that the product could be applied to FTIR interrogation of the chemical state (be it heat damage, degree of cure, etc.) of any resin bearing composite.The approach uses algorithms from remote sensing, and may be conformable in the future to a standoff inspection that could survey a large area in one acquisition.