An experimental study on the tensile behavior of the cracked aluminum plates repaired by fiber metal laminate (FML) patches

Fiber metal laminates (FMLs) are widely used in aerospace industries nowadays. Repairing of the cracks in these advanced materials was first done by some aeronautical laboratories in early 1970s. In this study, experimental investigations were done on the effect of repairing the center-cracked aluminum plates using the FML patches. The repairing processes were conducted to characterize the response of the repaired structures to tensile tests. The composite patches were made of one aluminum layer and two woven glass-epoxy composite layers. Three different crack lengths in three crack angles and different patch lay-ups were examined. It was observed that no matter what the crack length was, the more the crack angle is larger, the more ultimate tensile strength of the structure became. It was also indicated that the patch lay-up had an important effect on the tensile response of the repaired specimens. When the aluminum layer of the patches was farther from the repair zone, the ultimate tensile strength reached to its maximum value.