The proposed approach for Phase I of this effort brings together two key items that are needed to work in concert with one another: advanced fatigue assessment methods and non-destructive inspection & detection techniques. Successful synthesis of these elements and the engineering disciplines behind them will provide an optimized and advanced method of taking full advantage of engineered residual stresses in the safety and readiness of aircraft structure throughout the entire life cycle. The innovation in assessment methods has to include descriptions residual stress evolution and changing failure models and the resulting effects on structural capability. Detection techniques provide the quantification necessary to complement the assessments by measurement of residual stresses.
Benefit: AP/ES continues to focus on the research and development of analytical processes toward simulation of the fatigue process on nucleation, small growth, and onto structural failure of components. This advanced service life assessment capability places AP/ES into the unique position to pursue comprehensive solutions to problems across many air vehicles platforms and multiple industries that need to assess and maintain the integrity of their structure. AP/ES efforts have improved fatigue analytical models that account for surface integrity effects in the nucleation phase from constituent particles, fretting, effects of many types of corrosion, and the interaction of widespread or multiple site damage (WFD or MSD). AP/ES successes have been leading the industry in life prediction approaches that are presently being pursued by others in the AFRL and other DoD organizations. AP/ES models are readily integrated into or linked with the existing life prediction methodologies and codes, such as FASTRAN and AFGROW. The framework utilized by APES considers the infrastructure, structural integrity concepts, and philosophies of all aircraft users: Navy, US Air Force, and commercial / general aviation. This robust process enables our advances in life assessment methods to transition from the research stage through verification, and into application on air vehicles in three to four years. Our Commercialization and Business Plan support the development and transition to expedite the capture of benefits afforded by improved life assessment methods. The approach of this Phase I is geared toward developing this process for a select type of damage, that is, probabilistic nucleation time as affected by different surface conditions such as roughness and the concurrent development of inspection techniques. The development of a successful assessment process facilitates the application of the solutions to many other applications such as aircraft, spacecraft, automobiles, ships, bridges, and mechanical equipment systems. The advantage that would be afforded to AP/ES and other project participants, which includes the multiple aircraft customers and agencies, is that the Integration process is established along with the solution. The process thus enables rapid and cost effective incorporation into the particular customers infrastructure. The successful completion of this SBIR, considering all three phases, thus results in documentation of the technical adequacy and feasibility, documentation of the business case that will provide an example of the return on the investment of application of the solutions to particular aircraft problems, and tailoring of the methodology for integrating into current, already established ASIP concepts, ensuring delivery into practice. The proposed plan focuses on capturing the validated technology and tailoring advances in technology to practical applications. Success of this technology development and implementation will improve chances for exploiting additional opportunities in the complex problems being encountered during the life cycle of the aircraft structure. These business opportunities are not limited to U.S. markets alone, as the methods implementation supports European customers and our allies fleet, especially the Canadian fleet.
Keywords: Residual Stress, Dmi Strain Gages, X-Ray Diffraction, Eddy Current, Holistic Life Assessments
