Early Stage Fatigue Damage Characterization in Aluminum Alloys and Stainless Steels with Meandering Winding Magnetometer Technology

Abstract

It is shown that pre-crack and early stage fatigue damage can be characterized by a new sensor technology, the Meandering Winding Magnetometer (MWM™). This new technology consists of a conformable sensor, the MWM, and associated measurement grids that are model based. Measurements on type 304 stainless steel indicated that damage is readily detectable at 20% of life (N/NF = 0.2) and causes a 1.5% conductivity loss. Near failure the conductivity loss in the crack-free region was approximately 4%. In 2024 aluminum the onset of detectable fatigue damage was observed at approximately 50% of total life. For the probe geometry employed, the conductivity loss in the microcrack region just prior to failure was 7%; in the macrocrack region it reached 13%.

Performance Evaluation of a Carbon Nanotube Sensor for Fatigue Crack Monitoring of Metal Structures

“…Various sensing approaches have been studied for detecting and monitoring fatigue cracks in structures, including using crack propagation gages (CPGs) [ 14 , 15 ], electrochemical fatigue sensors (EFSs) [ 16 , 17 ], meandering winding magnetometers (MWMs) [ 17 , 18 , 19 ], large area electronics (LAE) strain sensing sheets [ 20 , 21 ], piezoelectric transducers, ultrasonic sensors [ 2 , 3 ], fiber Bragg grating ultrasonic sensors [ 22 ], thin film (styrene-ethylene/butylene-styrene - carbon black) sensors [ 23 ], and acoustic emission (AE) monitoring [ 24 , 25 , 26 ].…”