The Need and Requirements for Validating Damage Detection Capability
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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Structural Health Monitoring SHM has been proposed to benefit the maintenance cost and reliability of aircraft structures through the early detection of damage during service and in support of condition-based maintenance. At the same time, if the integrity of an aircraft component is dependent upon the performance of an SHM system to detect damage, which has recently been referred to as an in-situ NDE system by two airframe OEMs 1,2, the reliability of the validated capability of the SHM system must also be ensured over the service life of the aircraft. To enable the calculation of risk, which is the metric used by the US Air Force USAF to manage the integrity of structures, the capability of any inspection process must be assessed and integrated into the risk calculation. Thus, a qualification plan is required for both the validated capability, i.e. POD and false-positive rate, and the durability of the sensing technique. These requirements were established by the Aircraft Structural Integrity Program ASIP Senior Leader for the USAF, Mr. Charles Babish 3. Empirical assessment of the performance of an SHM system in such an environment is not a trivial manner and could readily be cost prohibitive. A protocol has been developed at the request of the AFRL Team Leader for Integrated System Health Assessment initiative that leverages current research and development efforts to minimize the amount of empirical data required for assessing the Probability of Detection POD of a damage detection system 4. The on-going effort uses models and transfer functions to minimize the need for empirical data and is called Model-assisted Probability of Detection, or MAPOD 5,6. The details defining these requirements and structure for the protocol to satisfy these requirements are presented.