Fatigue test of an integrally stiffened panel: Prediction and crack growth monitoring using acoustic emission

摘要

Airworthiness regulations require operating advanced aircraft structures in compliance with a damage tolerance philosophy. Therefore, flight safety and structure reliability in service must be ensured using many types of additional activities, such as damage detection, crack growth prediction and critical size of cracks determination. As a result, the structural health monitoring of aircrafts using various detection principles is needed. The paper documents the use of an acoustic emission method for the health monitoring of a typical airframe structure. It is represented by an integrally stiffened metallic panel demonstrating a bottom wing panel of a commuter aircraft. A fatigue test of the panel under a flight-by-flight loading sequence was performed. The crack growth was monitored by a visual method (VT) and an acoustic emission (AE) method. Several AE sensors placed in different configurations were used. AE reached very good agreement with the crack growth data, although the presented test was partially conducted in a noisy environment. The de-noised AE parameters were evaluated according to the actual position of the sensors and the crack tip. The influence of stringers on the measured signal changes was studied as well.