Papers by Keyword: Equivalent Crack Length

Abstract: This article examines the fracture toughness of end notched flexure (ENF) composite specimens of three different lay-ups. Experiments were conducted on these glass/epoxy specimens and the critical fracture energy,, was evaluated based on compliance based beam method (CBBM). Classical methods require crack length measurements, which are not easy to obtain as propagation occurs rapidly without a clear opening. The CBBM is based on crack equivalent concept, which does not require crack length monitoring during propagation and hence the crack growth resistance curve (R-curve) can be generated in a much easier way. Moreover, the CBBM accounts the non-negligible energy dissipation in the fracture process zone (FPZ) in addition to stress concentrations near crack tip, contact between specimen arms at the pre-crack region and root rotation effects. Hence, the complete R-curves of ENF specimens of different lay-ups were obtained using the CBBM with higher degree of accuracy. It was observed that the unidirectional specimen did show higher propagation toughness value than the angle-ply and cross-ply specimens.

Abstract: In fracture tests involving the Single-Edge-Notched beam loaded in Three or Four-Point-Bending as well as in other specimen shapes, the specimen weight contributes to the overall loading of the system. Unless special methods are put into practice, the contribution of the specimen weight is not compensated, leading to misevaluations of fracture parameters obtained in the experiments. In this work a method taking into account the exact contribution of the specimen self-weight is proposed to evaluate the Resistance-curve of mortar. Cohesive crack modeling accounting for the structure self-weight is used to generate the necessary load-displacement response to perform the validation of the proposed method.