The same DR method is used to detect a dynamic process and switch to a dynamic calculation. The static process is solved by a dynamic relaxation (DR) method together with a modified technique to enhance the convergence rate. We chose a discrete cohesive model for concrete fracture, an interface bond-slip model for the deterioration between concrete and steel rebar, both combined with an insertion algorithm. In order to study this phenomenon numerically, a model capable of dealing with both static and dynamic crack propagation as well as the natural transition of these two regimes is necessary. In this work, we aim to tackle one of the most devastating failure modes in reinforced concrete (RC) structures: the diagonal-tension failure. This suggests that simulation of the fracture of non-irradiated polygranular nuclear graphite requires a material model capable of showing softening behaviour. The measurements demonstrate the existence of a cohesive fracture process zone ahead of the crack tip, which is a characteristic of quasi-brittle materials. The DVC-measured displacement field was used to measure and map the crack opening displacements in 3D the experimentally calculated crack opening displacements were consistent with the FE-predicted values. Tomographic absorption contrast images were obtained from the specimen before and after crack propagation, whilst loaded. A three-dimensional linear elastic finite element simulation of the specimen obtained the relations between crack length, opening displacement and stress intensity factor along the crack front. This paper reports a study of the fracture behaviour of a short-bar chevron notch crack propagation specimen fabricated from polygranular nuclear graphite - a quasi-brittle material. X-ray computed tomography (XCT) provides valuable insights into the structures within materials: when XCT is combined with digital volume correlation (DVC) the response to applied loads can be measured with high precision in the form of the three-dimensional displacement field within the material. Observations of fracture are generally restricted to the surface of test specimens yet the fracture process occurs within the material.

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