Fracture behavior of a A 6061 layers of sandwich plates

This research work studies the effect of tensile properties mismatch on fracture driving force in sandwich plates using Double Edge Notched Tension (D E N T) specimens. Notched specimens are used due to the difficulty in fatigue pre-cracking small sized specimens of sandwich plates. Two sandwich plates, S P1 and S P2, composed of different aluminum alloys layers are studied. A A 6061 is used as cladding material in both cases while A A 2017 and Al 1100 are used as core materials for S P1 and S P2, respectively. Homogenous specimens made of A A 6061 are also studied for comparison. The critical fracture load is determined experimentally. Finite element elastic-plastic analysis is performed to evaluate the effect of tensile properties mismatch on fracture driving force ahead of notch tip, Jtip. The results showed that the mismatch in the tensile properties between sandwich plate layers affects Jtip values. In case of S P1, the notch tip is shielded from the remote loading where Jtip is smaller than the remote one vice versa in case of S P2 where Jtip is amplified. It is demonstrated that, the amount of shielding is normally less than amplification. As in the case of Jtip, stress concentration factor (Kσ) increased in the case of S P2 while it decreased in S P1 case. Also, the magnitude of the increase in Kσ in the case of amplification is larger than the magnitude of the decrease in Kσ in the case of shielding. In the meantime, notch depth with material tensile properties play an important role in the fracture process while effect of the studied notch radii is minor.