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Thursday, May 18, 2006 - 8:30 AM
NEHMP065.2

Probabilistic Methods and Software for Assessing Tradeoffs in Maintenance Programs Incorporating Nondestructive Evaluation and Structural Health Monitoring

E. A. Medina, Radiance Technologies, Inc., Dayton, OH; J. C. Aldrin, Computational Tools, Gurnee, IL; J. S. Knopp, US Air Force Research Laboratory, Wright-Patterson AFB, OH; D. A. Allwine, M. Qadeer Ahmed, J. E. Fisher, Austral Engineering & Software, Inc., Athens, OH

Various structural health monitoring (SHM) technologies have recently been proposed for development and possible implementation. Decision support tools are needed that enable tradeoff and cost-benefit analyses for optimizing the value of inserting these SHM technologies into air- and space-vehicle maintenance programs. This work builds upon the development of VNDE, a software platform for integrating NDE design and product life management models. Based on probabilistic models of fatigue crack growth, detection, and repair, previous VNDE demonstration cases showed the ability of the methodology to assess and optimize effects of changes in inspection parameters and scheduling on time-dependent reliability and maintenance cost objectives. While probabilistic risk management models of the type used in the VNDE software have not yet gained widespread use, they are regarded by many in the maintenance community as a means for achieving extended life at reduced costs while maintaining safety, among other benefits. VNDE can provide a convenient platform for applying probabilistic risk management models, value analysis, and decision support tools to facilitate the implementation of improved maintenance technologies. In this work, the VNDE model has been enhanced by probabilistic model components representing SHM systems and their integration into a hybrid life management approach where SHM and NDE are utilized in a complementary fashion. The combined model addresses the use of SHM systems together with secondary in-field and depot inspections, tracking of repairs and removal from service due to SHM indications, and consideration of SHM system degradation over time. Demonstration cases include the analysis of near- and long-term costs and benefits of SHM applications as used in combination with NDE technologies. The presentation will describe the current status and development plans for the software, and results of tradeoff studies on example aircraft maintenance problems that illustrate the value of these decision support tools and models.

Summary: The VNDE software has been developed through a U.S. Air Force Small Business Innovation Research project. VNDE aims to facilitate the application of probabilistic risk management models and optimization-based design technologies to the problem of system maintenance and service life extension. Recent model enhancements make VNDE capable of analyzing reliability and cost tradeoffs for maintenance plans that complementarily utilize non-destructive inspection and structural health monitoring technologies. This presentation will describe status and plans for the VNDE software and results of demonstration examples.