Numerical analysis of cracked aluminium panel repaired with functionally graded adhesively bonded patch

Abstract

Aircraft maintenance is becoming more important as a means of enhancing structural integrity and prolonging the service life of older aircraft. The bonded composite repair is the most popular among the various repair processes because of its ability to join similar and dissimilar materials. In the present research, the performance of a single sided functionally graded adhesively bonded patch on a centre crack aluminium panel was evaluated using 3D FE analysis. The integrity of a graded crack patch repair system is investigated using the fracture mechanics principle. The strain energy release rate (SERR) GI is used to analyse damage/crack growth and evaluated by utilising the virtual crack closure technique (VCCT), which is based on the concept of linear elastic fracture mechanics (LEFM). The gradation of patch is carried out with linear profile with different modulus ratios in the preferred direction such that using more flexible adhesive at centre of crack and stiffer adhesive ahead of crack/damage. From exhaustive finite element analyses, substantial reduction in crack growth driving forces (SERR) is observed in functionally graded crack-patch repair system. Effect of different modulus ratios on SERR has been also studied. In view of above, graded crack-patch repair system can be recommended for designer.