Applying thermoelasticity to study stress relief and crack propagation in aluminium specimens patched with composite material

Abstract

The context of the study is the preventive reinforcement of aluminium structures with bonded composite patches. The paper deals with stress relief in the substrate under tensile loading, as well as crack propagation in the adhesive during fatigue tests. For this purpose, temperature measurements are performed through the thickness of the specimen using an infrared camera. The procedure provides two types of information. First, thermoelasticity is used to study the relief in the aluminium substrate during cyclic loading: stress distribution, global relief, and progressive load transfer zone. Second, the study allows the tracking of patch disbond and characterization of mode-II crack propagation in the adhesive. A Paris law is determined for the design of bonded composite patches subjected to tensile fatigue loading.