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In the present paper effects of skew initial delamination length in DCB specimens on evaluating modc - I delamination fracture energy (GIc) were investigated. Delamination growth analysis incorporating finite element method is used to model delamination growth initiated from a skew front and determine loaddisplaceIl1ent - delamination length data for a prescribed GIc as delamination propagated along the specimen. Then, the standard test data reduction methods have been applied to the numerical data to evaluate the values of GIc for each position of delamination front.
It is seen that skew front progressively change to a curved front
during a few millimeter growth. Part of this growth occurs within the specimen which is not visible from the specimen edges where the delamination lengths were recorded during a test. Therefore, the load drop for this growth should not be related to the material behavior. It is also seen that the difference between delamination lengths measured at either side of the specimen can have a significant effect on GIc calculated by the standard methods. To eliminate this error in an actual test, it is suggested that the data for a first few millimeters of growth be neglected.