[117] Acoustic emission characterisation of two pre-cracked specimens
A Galvez1,2, D Galar1,2, A Alonso1, B Errasti-Alcala1, I Bienvenido3, P Ortego4 and E Juuso5
1TECNALIA, Spain
2Luleå University of Technology, Sweden
3ZEUKO, Spain
4University of the Basque Country (UPV/EHU), Spain
5University of Oulu, Finland
This article contains the experiments carried out to study the capabilities of acoustic emission (AE) in a ship-to-shore (STS) crane. This solution studies the implementation of structural health monitoring (SHM) in an STS crane based on the AE technique for detecting cracks and assessing their growth in steel elements subjected to fatigue. The first experiment is performed using a compact tension specimen (CT) made of steel S355, the dimensions of which are 125 × 120 × 50 mm and its cracks and dimensions are defined based on ASTM and ISO standards. The CT is monitored using AE sensors and then the features are extracted from the raw data and used to train, test and validate an unsupervised model. This prediction model obtains a remarkable accuracy: crack detection at a sizing of 3 mm length. As the CT dimensions are small, it is difficult to evaluate the attenuation of AE signals, which is completely necessary for monitoring STS cranes. Therefore, a second experiment is performed using a panel made of steel S355, the dimensions of which are 2120 × 200 × 8 mm; the panel contains a crack of 50 × 3 mm. This experiment is performed to analyse the AE signals that come from cracks, specifically to assess signal attenuation, how the attenuation affects crack detection in the panel and features evolution during crack propagation. This is led by monitoring the crack growth with crack detection gauges and installing the AE sensors at different distances of the crack. The assessment is used to develop an unsupervised model to detect cracks and an algorithm for localising them.
