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Measurement of dynamic strength of concrete at impact relevant strain rates and pressures is the purpose of the described study. Therefore, an experimental design of direct planar impact experiments with longitudinal and transverse strain gauges is analyzed in predictive hydrocode simulations using an elastic-plastic damage model for concrete. The calculations and first experimental results on mortar show decreasing phase velocities of stress waves both in longitudinal and lateral gauges. The model clearly associates it with the onset of damage, possibly interpreted as a failure wave. Numerical analysis is furthermore used to compare a monolithic target block to a thoroughly assembled concrete sample in order to include flat gauges in the material. The planned experimental procedure to derive wave speeds, particle velocities and strain rates from stress measurements is anticipated and validated on the basis of simulated gauge signals. The most important finding is the prediction and first experimental confirmation that concrete ultimate strength and damaged yield stress can be derived at strain rates in the order of 10 4 /s from the proposed type of experiments. This technique promises new insight into the strength and failure processes of concrete in the challenging loading region around the characteristic minimum of its shock particle velocity relationship.

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Ballistic performance analysis of ultra-high molecular weight polyethylene (UHMW-PE) is critical for the design of armour systems against ballistic threats. However, no validated modelling strategy has been published in literature for UHMW-PE composite that captures the penetration and damage mechanisms of thick targets impacted between 900 m/s and 2000 m/s. Here we propose a mechanistically-based and extensively validated methodology for the ballistic impact analysis of thick UHMW-PE composite. The methodology uses a non-linear orthotropic continuum model that describes the composite response using a non-linear equation of state (EoS), orthotropic elastic plastic strength with directional hardening and orthotropic failure criteria. A new sub-laminate discretisation approach is proposed that allows the model to more accurately capture out-of-plane failure. The model is extensively validated using experimental ballistic data for a wide range of UHMW-PE target thicknesses up to 102 mm against 12.7 mm and 20 mm calibre fragment simulating projectiles (FSPs) with impact velocities between 400 m/s and 2000 m/s. Very good overall agreement with experimental results is seen for depth of penetration, ballistic limit and residual velocity, while the penetration mechanisms and target bulge behaviour are accurately predicted. The model can be used to reduce the volume of testing typically required to design and assess thick UHMW-PE composite in ballistic impact applications

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The Riedel-Hiermaier-Thoma model, which is available in ANSYS Autodyn since 2000 as a description of concrete and similar geological materials in highly dynamic loading situations, has recently been implemented in the multi-purpose Finite Element code LS-DYNA. This article gives a brief overview of the physical details and verifies the new implementation by comparing single element test results with the established Autodyn code. Four real cases, ranging from low to very high pressure loading by impact, penetration and blast, are used to demonstrate thereafter the validity of the model in a wide range of applications. Simulation results from both codes are compared to experimental data at several occasions. Although slight differences between the implementations are observed, the overall agreement, both between the codes and with experiments, is very good. The systematic work in this publication demonstrates that the RiedelHiermaier-Thoma model is a useful addition to the LS-DYNA material library and shall motivate research to apply the model over a wide range of applications. A comprehensive, physically derived dataset is provided for a C70/85 high-strength concrete used in one validation case.