Comparison of Fracture and Fatigue Properties of Clad 7075-T6 Aluminum in Monolithic and Laminated Forms

Laminated metal-metal composites can have attractive fracture toughness properties; they also offer potentially good fatigue performance. These attributes are reviewed and prospects for improvement discussed. Weak interlaminar bonds are seen to be important, while quite thin layers seem to be most promising for laminates of higher strength materials.

The experimental program utilized 0.033 in (0.84 mm) thick laminae of 7075-T6 aluminum alloy, adhesively bonded.

Eight-layer composites were compared with solid sheets of nearly the same total metal thickness. Both fracture toughness and fatigue properties were determined. K_c values of more than double the K_Ic for this alloy were observed in the laminates, while fatigue performance as indicated by comparative S-N curves was found to be slightly improved.