Adhesive defect density estimation applying the acoustic emission technique

The aim of this work is to study in depth the use of the acoustic emissions, as a non-destructive testing technique, applied to the adhesively bonded joints. In a previous paper, three defect densities of the adhesive, 0%, 50% and 100%, were investigated, while in the present work two more intermediate values have been considered: 25% and 75%. The first goal of this paper is to confirm the good correlation, highlighted in the previous one, between the adhesive defect density and the cumulative counts of the acoustic emissions; the second goal is to improve a methodology which might be capable of estimating, with accuracy, the adhesive bonding defect and the final releasing moment of the assembled joints. In this paper, the new results have been integrated with the previous ones and a more detailed map of the adhesive slope variations is presented.