Detection and Monitoring of Fatigue Cracks in Metallic Structures Using Acoustic Emission: Routes to Quantification of Probability of Detection

Abstract:

The performance and reliability of Structural Health Monitoring (SHM) techniques remain largely unquantified. This is in contrast to the probability of detection (POD) and sensitivity of manual non destructive inspection methods which are well characterised. In this study factors influencing the rates of emission of Acoustic Emission (AE) signals from propagating fatigue cracks were investigated. Fatigue crack growth experiments were performed in 2014 T6 aluminium sheet to observe the effects of changes in crack length, loading spectrum and sample geometry on rates of emission and the probability of detecting and locating the fatigue crack. Significant variation was found in the rates of AE signal generation during crack progression from initiation to final failure. AE signals at any point in the failure process were found to result from different failure mechanisms operating at particular stages in the failure process.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 1268-1274
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.1268
• Online since: March 2014
• Authors: Daniel Gagar, Peter Foote, Phil E. Irving*
• Keywords: Acoustic Emission (AE), Fatigue Crack, Probability of Detection, Structural Health Monitoring (SHM)

References

[1] Ciampa, F. and Meo, M. (2010), A new algorithm for acoustic emission localization and flexural group velocity determination in anisotropic structures, Composites Part A: Applied Science and Manufacturing, vol. 41, no. 12, pp.1777-1786.

DOI: 10.1016/j.compositesa.2010.08.013

[2] Rummel, W. D., Todd Jr., P. H., Rathke, R. A. and Castner, W. L. (1974), Detection of Fatigue Cracks by Nondestructive Test Methods., Materials Evaluation, vol. 32, no. 10, pp.205-212.

[3] Spencer, F. W. (2001), Estimating Probability of Detection Curves from Regression Data, Materials Evaluation, vol. 59, no. 7, pp.866-870.

[4] Botev, Z.I., Grotowski, J.F. and Kroese, D.P., ( 2010), Kernel Density Estimation via Difussion, Institute of Mathematical Statistics.

[5] NASA (2008), Non destructive evaluation requirements for fracture critical components, NASA-STD-5009, National Aeronautics and Space Administration.

[6] NASA (1985), Standard NDE guidelines and requirements for fracture control programs, MSFC-STD-1249, National Aeronautics and Space Administration.

[7] Scruby, C. B., Baldwin, G. R. and Stacey, K. A. (1985), Characterisation of fatigue crack extension by quantitative acoustic emission, International Journal of Fracture, vol. 28, no. 4, pp.201-222.

DOI: 10.1007/bf00035216

[8] Newman Jr., J. C. (1984), A crack opening stress equation for fatigue crack growth, International Journal of Fracture, vol. 24, no. 4, pp. R131-R135.

DOI: 10.1007/bf00020751