Stress intensity factor analysis for notched cracked structure repaired by composite patching

In this paper, we investigated the crack growth behaviour of cracked thin aluminium plate repaired with bonded composite patch. The finite element method is used to study the performance of the bonded composite reinforcement or repair for reducing the stress concentration at a semicircular lateral notch and repairing cracks starting from this kind of notch. The effects of the adhesive properties and the patch size on the stress intensity factor variation at the crack tip in mode I and mixed mode are highlighted. The obtained results show that the stress concentration factor at the semicircular notch root and the stress intensity factor of a crack starting from notch are reduced with the increase of the diameter and the number of the semicircular patch. The maximum reduction of stress intensity factor is about 42% and 54%, respectively for single and double patch. However, the gain in the patch thickness increases with the increase of the crack length and it decreases when the patch thickness increases. The adhesive properties must be optimised in order to increase the performance of the patch repair or reinforcement.