Fatigue crack propagation of aluminum alloy based on acoustic emission monitoring

The acoustic emission technique was used to monitor the fatigue crack propagation of 7N01 aluminum alloy single-edge notched three-point bend specimens under different stress ratio and peak load. The relationship between the crack growth rate,acoustic emission count rate and stress intensity factor range was established. The results show that most of the acoustic emission signals were produced in the low stress cyclic loading stage because the acoustic emission activity in low-stress phase was mainly related to the plastic deformation and crack closure in crack tip,and the acoustic emission count exponentially grew with the stress intensity factor. Based on the relationship between the acoustic emission count rate and crack growth rate,the remaining life of fatigue-damaged structures could be predicted.