Review of the Use of Magnetostrictive Sensor Technology for Inspection and Monitoring of Aging Aircraft

摘要

There is a need for inspection and structural integrity monitoring (SIM) for diagnostics and prognostics on structural systems to enhance safety and reliability, minimize downtime, and reduce operating and maintenance costs. This need exists across various industries including aircraft and aerospace. Today, many types of sensors are being considered for monitoring that are passive such as fiber optics, strain gauges, thermometers, and accelerometers. They detect environmental conditions the structure is subjected that may be useful to infer the integrity and safety of the structure. However, the reliability and confidence of the monitoring sensors could be significantly improved if active, instead of passive, sensors were used that, when actuated, could inspect critical load-bearing areas of the structure and detect and locate actual damage in the structure such as cracks, debonds, and corrosion wastage. One candidate for active monitoring sensor applications is the guided-wave sensor. Guided waves, such as Lamb waves and shear horizontal (SH) waves in a plate structure and longitudinal waves and torsional waves in a cylindrical structure, can propagate a long distance along the structure and inspect and monitor a large area of the structure for defects and structural conditions from a single fixed sensor location. The guided-wave sensor, therefore, would be ideal for monitoring large structures found in aircraft and spacecraft. Southwest Research Institute (SwRI) has been conducting research and development in the use of magnetostrictively produced guided waves as a sensor technology for detecting defects. Sensors, based on the magnetostrictive sensor (MsS) technology developed and patented by SwRI, are inexpensive to build and are flat, lightweight, surface-mounted, and durable; therefore, the sensors have high potential for practical applications.