Imaging Ultrasonic Sensor System SWISS Completed 60.000 Simulated Flight Hours to Check Structural Integrity of Aircraft Subcomponent

摘要

Many military platforms such as fighter aircraft are nowadays operated for several decades under sometimes varying missions. Additional requirements resulting from more severe fatigue spectra or extended life for these platforms may require additional means of ensuring structural integrity. It is then important to gain the maximum usage (fatigue life) of aircraft components most efficiently still ensuring structural integrity at all times. Conventional structural health monitoring systems are typically based on loads and usage monitoring. Together with modern non destructive damage detection techniques it could be possible to safely operate even aged platforms. This goal is achieved by periodic examinations in order to ensure that a structural item is free of damage. However, the dismantling of structures for the purpose of non destructive testing can be very costly, time intensive and sometimes harmful to the surrounding structure itself. Therefore integrated, reliable and affordable damage detection techniques are needed to avoid disassembly where economically or technically justified. Especially for well known hot spots an integrated damage sensor could provide an alternative solution to conventional procedures. SWISS (Smart Wide area Imaging Sensor System) is an ultrasonic imaging approach. A small sensor is permanently surface mounted on the component that is to be monitored. Typically the sensor is activated on ground and interrogated via cables that are built into the platform. These sensors facilitate the examination of the internal structure of a subcomponent. The ultrasonic beam is electronically controlled in order to scan the most critical areas from a fixed position. Functionality aspects as well as practicability issues of such a technology had to be addressed and solved. As a result of this study, simulated fatigue tests on a real complex fitting structure have proven the reliability of the imaging ultrasonic sensor under laboratory conditions for more than 60000 simulated flight hours without problems and that the high volume coverage proved to be beneficial for detecting even unexpected damages.