الفهرس 
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Abstract
This research work studies the effect of tensile properties mismatch on fracture
driving force in sandwich plates using Double Edge Notched Tension (DENT)
specimens. Notched specimens are used due to the difficulty in fatigue pre-cracking
small sized specimens of sandwich plates. Two sandwich plates, SP1 and SP2,
composed of different aluminum alloys layers are studied. AA6061 is used as
cladding material in both cases while AA2017 and Al 1100 are used as core materials
for SP1 and SP2, respectively. Homogenous specimens made of AA6061 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 SP1, the notch tip is shielded from the remote
loading where Jtip is smaller than the remote one vice versa in case of SP2 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 SP2 while it decreased in SP1case. 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.