Computational analysis of crack deflection at a bi-material interface by means of initially rigid and elastic mixed-mode traction-separation laws

  • I. van der Kuil

Student thesis: Master


Numerical analyses of interfaces in layered samples are commonly performed with cohesive zone models, for which several types of traction-separation laws have been proposed. Most laws are initially elastic, which may result in an undesired compliance of the material when modeling bulk fracture. To overcome this problem, this study presents an exponential initially rigid tractionseparation law. The initially rigid model is compared to an initially elastic model for various loading conditions. It is shown that the proposed model is capable of describing both single mode and mixed-mode behavior, and correctly determines the work-of-separation. A dissipation-based arc-length solver, compatible with both models, is implemented to account for snap-backs in the load-displacement curve. The competition between bulk fracture and delamination in a bi-material sample is analyzed, in which the substrate is modeled with subsequently initially rigid and initially elastic models. The results are in agreement with an LEFM solution for substrate fracture, but the assumption of pure shear opening of the interface results in an overprediction of the required load for delamination. Both models predict similar substrate-to-interface strength and toughness ratios at which transition between the failure modes occurs and an increased load is observed for equal fracture length scales of the substrate and interface.
Date of Award22 Mar 2019
Original languageEnglish
SupervisorJoris J.C. Remmers (Supervisor 1) & Olaf van der Sluis (Supervisor 2)

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