Fatigue test of an integrally stiffened panel: Prediction and crack growth monitoring using acoustic emission
Lenka Michalcová, Roman Růžek
2016
Procedia Structural Integrity
During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation
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... mpany, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data. Abstract 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. Abstract 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.
doi:10.1016/j.prostr.2016.06.381
fatcat:usgpccg2hnfzjbonmdkbhdmodm