Flight Testing of an Ultrasonic Based SHM System

We have been developing an Ultrasonic based structural health monitoring (SHM) system which can provide essential information on structural integrity of airframes. The information can contribute to create novel design philosophies, improve inspection activities in manufacturing processes, and optimization of aircraft operation with the condition-based maintenance. In the SHM system, ultrasonic Lamb waves are measured and analyzed to evaluate damages in airframes because ultrasonic Lamb waves changes with the changes of structures such as damage initiations and their growth. In order to achieve implementation of the SHM system to actual operating aircraft, we have conducted various types of tests for over 15 years, in which we assessed damage detection capability, accuracy and probability of damage detection, environmental durability, and applicability to aircraft system, and so on.

In this report, results of a flight testing as a pre-trial toward the implementation of the SHM system were summarized. In the flight testing, we evaluated influences of environmental conditions to measurements of ultrasonic Lamb waves and detection capability of the SHM system in actual aircraft operating conditions with a flying test bed owned by Japan Aerospace eXploration Agency (JAXA). From the results of the flight testing, it was confirmed that ultrasonic waves could be measured in flight conditions just like on ground and also damages introduced to the test specimen could be detected by analyzing the changes in waveforms of the ultrasonic Lamb waves even in the actual operating aircraft.