On the use of thermographic technique to assess the fatigue performance of bonded joints

The thermographic technique is based on the heat released during dynamic loading cycles, correlating the temperature variation on specimen's surface with the applied stress amplitude. An abrupt temperature variation under a specific stress level reveals the presence of an irreversible phenomenon inside the material, which could be associated with fatigue damage process. In this work, the fatigue performance of bonded joints is assessed by carrying out fatigue tests in a servo-hydraulic machine monitored continuously by a thermographic acquisition system, with the utilization of end notched flexure specimens composed by two steel plates of ASTM A36, bonded together with epoxy adhesive. The results confirm that the thermographic technique is quite promising as an alternative approach to estimate the bonded joint fatigue strength.