Progressive Fatigue Damage Assessment in Adhesively Bonded Joints Using the Back-Face Strain Technique

Adhesively bonded joints are increasingly being utilised in various industries because of their outstanding advantages. However, there are a few aspects, such as difficulty in detection and assessment of damage during service loading that prevent a more widespread use of adhesive bonding. The experimental back-face strain technique which is a localised damage assessment technique can be considered as a reliable approach for assessing damage in adhesively bonded joints. In this technique the strain gauges are attached on the Backface surfaces of the bonded joint. The measured strain during the onset and growth of damage changes and this change is utilised to indicate the damage. In this paper, the progressive fatigue damage in two adhesively bonded joints, namely the single lap and the mixed-mode flexure joints, was assessed using the back-face strain, compliance and crack length measurement techniques.