Thermoshearographic Methodology for Strain Mapping

ABSTRACT: In response to the Air Force need for a methodology to accurately map strain distributions in hot composite structures, Physical Optics Corporation (POC) proposes to complete the development of a new ThermoShearographic methodology for Strain Mapping (TSSM), based on dynamic monitoring of in-plane strain variation and temperature distribution over an anisotropic specimen surface. In Phase I, POC successfully demonstrated the feasibility of the proposed methodology by assembling and testing the prototype, which accurately measures strain distribution on composite coupon surfaces under fatigue and thermal load. The results were used by Materials Research & Design, Inc. in their predictive model to calculate thermal and mechanical strain distributions. In Phase II, POC will optimize the Phase I prototype, advancing it to a full-scale TSSM system with the integrated predictive model, allowing accurate mapping of strain and temperature distribution in a hot, mechanically loaded composite structure and estimating damage progression with a low degree of uncertainty. TSSM capabilities will be demonstrated in inspection of composite structures under conditions experienced in modern gas turbine engines. The tested Phase II system will be delivered to the Air Force for further evaluation. By the end of Phase II we plan to reach technical readiness level (TRL)-4/5. BENEFIT: Beyond quality assurance and quality control of composite structures for military aircraft, where the benefits of this methodology are obvious, TSSM will offer benefits in inspection of composite materials and parts in land-based propulsion and power-generation systems, particularly in the automotive and boating industries.