OBJECTIVE: Design and develop an on-aircraft method or tool to identify and evaluate incipient heat damage in advanced composite material systems. DESCRIPTION: The need to detect and evaluate incipient composite degradation and to understand the effects on airframe viability is critical to both weapon system operating costs and mission safety. The increased use of advanced composites in the structural makeup of naval aircraft directly raises the probability of overheating those materials. Common overheating events include exhaust impingement, extended afterburner usage, repair induced overheating and chemical fire. Unidentified heat damage can result in losses due to both omission and commission. Millions of dollars in replacement parts are lost and mission availability can be degraded if parts are scrapped unnecessarily. Conversely, if damaged parts are permitted to fly the risk to personnel, weapons systems and overall mission success becomes significant. Currently there is no standard and accepted non-destructive inspection (NDI) technique for fully identifying the extent of heat damage to composite materials caused by heat damage. While damaged paint, charred surfaces and disbonds are readily identified by current NDI techniques, non-visually apparent damage is currently difficult to identify and impossible to quantify. The ideal system would non-destructively examine a composite part in-situ and determine not only if incipient heat damage exists but also the extent of that damage and its impact to the part. This innovation would determine bulk property loss through part sections or provide surface condition information suitable for ply-by-ply review. Both clean, resin rich areas and sanded surfaces should be capable of interrogation with the novel technology. Evaluation through paint/coatings is a valuable additional feature. A novel inspection technology is sought that can demonstrate correlation between non-visible heat damage, material property degradation and system response. The long term goal for this program includes the ability to provide on-aircraft evaluation, the target technology should be easily calibrated, robust enough for Fleet Readiness Center (FRC) or shipboard use and readily producible. Different responses would be expected for different material systems. The ideal technology would be adaptable for use with multiple composite material systems. PHASE I: Design, develop and determine the technical feasibility of an on-aircraft method or tool to determine the extent and resulting structural degradation of composite material parts subject to incipient heat damage. Demonstrate correlation capability suitable for use in structural evaluation of damaged material. Initial material system should be BMI based with expansion possible to epoxy systems. PHASE II: Produce and demonstrate prototype hand-held Heat Damage Detection & Evaluation Unit (HDDEU) capable of reliably determining the area affected by heat damage and the resultant property degradation on a variety of resin/fiber systems based on results of Phase I. PHASE III: Finalize HDDEU to be easily calibrated, robust enough for FRC/Shipboard use and readily producible. Transition HDDEU to appropriate platforms. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Results of this SBIR can be commercialized through the major aerospace and aviation OEMs for the private sector market. HDDEU should be transitioned to a production model suitable for commercial sale. REFERENCES: 1. Sathish, S., Welter, J., Reibel, R. & Buynak, C. (2005). Thermo-Elastic Characterization of Heat Damage in Carbon Fiber Epoxy Composites. AIP Conference Proceedings, Vol 820. http://proceedings.aip.org/resource/2/apcpcs/820/1/1015_1?isAuthorized=no 2. Frame, B.J., Janke, C.J., Simpson, W.A. Jr., & Ziegler, R.E. (1998). Composite Heat Damage. Oak Ridge National Laboratory, ORNL/ATD-33. http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6949632 3. Fisher, W.G., Storey, J.M.E., Sharp, S.L., Janke, C.J. & Wachter, E.A. (1995). Nondestructive Inspection of Graphite-Epoxy Composites for Heat Damage Using Laser-Induced Fluorescence, Applied Spectroscopy. 49, 1225-1231. http://www.ingentaconnect.com/content/sas/sas/1995/00000049/00000009/art00003 4. Welter, J. , et al. (2011). Development of a Nondestructive Non-Contact Acousto-Thermal Evaluation Technique for Damage Detection in Materials. University of Dayton, Report A204355.