Acoustic emission behaviour during crack growth of 7075-T651 Al alloy

Plastic deformation of 7075-T651 aluminum alloy is known to produce intense acoustic emission, which is usually related to the fracture of second phase particles. After fracture toughness tests, the fractured particles are found in a narrow zone along the crack path, implying that a strong correlation should exist between the amount of crack growth and the acoustic emission cumulative count. The acoustic emission behaviour was modelled assuming linear elastic fracture mechanics and that the cumulative count was related to the evolution of the plastic zone size associated with the propagating crack. The model was based on the GR resistance curve and on quantitative analysis of second phase particles. Good agreement was obtained between the predicted and observed acoustic emission behaviour.