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The modelling of concrete and its dynamic strength analysis has been an interesting field which seeks many researchers' attention for the last few decades. The material behavior of concrete in extreme dynamic events like blast and impact calls for the understanding of its dynamic characterization as well which demand a suitable material model that can depict the behavior of concrete under high strain rate, high pressure, and large deformations. One of the most used constitutive material models for concrete is HJC (Holmquist Johnson Cook). This model covers most of the essential features of concrete pertaining to response against blast and impact loads. The objective of this paper is to provide an in-depth assessment of the HJC model implemented in ABAQUS Explicit finite element code. The assessment involves various tests such as compression, tensile and tri-axial tests on a single element followed by validation of the numerical model with the help of ballistic experimental tests available in the open literature. Finally based on the assessment, the HJC material model utility for the behavior of thin i.e., H/d ≥ 5, UHPC (Ultra High-Performance Concrete) targets against impact loading has been discussed.

A problem for a central crack in a plate subjected to plane strain conditions is investigated. Mode I crack loading is created by a dynamic pressure pulse applied at a large distance from the crack. It was found that for a certain combination of amplitude and duration of the pulse applied, the energy transmitted to the sample has a strongly marked minimum, meaning that with the pulse amplitude or duration moving away from the optimal values, minimum energy required for initiation of crack growth increases rapidly. The results obtained indicate a possibility to optimise energy consumption of different industrial processes connected with fracture. Much could be gained in, for example, drilling or rock pounding where energy input accounts for the largest part of the process cost. Presumably further investigation of the effect observed can make it possible to predict optimal energy saving parameters, i.e. frequency and amplitude of impacts, for industrial devices, e.g. bores, grinding machines, and hence significantly reduce the process cost. The prediction can be given based on the parameters of the media fractured (material parameters, prevalent crack length and orientation, etc.).