Numerical assessment for impact strength measurements in concrete materials

Abstract

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.

Modifications of RHT material model for improved numerical simulation of dynamic response of concrete

“…The original RHT model is well documented in previous publications [1, 5,9] and a concise overview is also provided in [15]. In this section, we will focus on the analysis of a few issues and present the detailed modifications to the original RHT model.…”

“…Recent advancements saw the development of several comprehensive concrete models that are aimed at high-impulsive load applications, with consideration of such effects as pressure hardening, strain hardening, material softening and rate-dependency. Models of this category include the RHT model [1, 9,10], the K&C model [11,12] and JHC concrete model [13].…”

Collision Behavior Evaluation of Flexible Concrete Mattress Depending on Material Models

“…일반적으로 콘크리트의 충돌해석은 콘크리트 방호벽에 대한 탄두와 같은 고속 발사체의 관통성능을 평가하기 위해 주로 수 행되었으며 (Clegg et al, 2002;Rempling, 2004;Tham, 2005), 개발된 콘크리트의 고급 재료모델 또한 이와 관련한 것이다 (Riedel et al, 1999;Riedel et al, 2009 (Fig. 4).…”

Determination and Validation of Parameters for Riedel-Hiermaier-Thoma Concrete Model

“…Because of the residual surface can so far not be measured 8 , the residual strength parameters B and M cannot be determined by experimental data. However, the parametric studies, conducted by leppanen 12 , indicate that the simulation results were reasonable and fit the experiment results well by setting B and M equal to 1.50 and 0.70, respectively.…”

“…In addition, the Dugdale and Macdonald's approximation 13 for the Grüneisen coefficient γ is applied, γ = 2s-1. By using the Eqn (22) where ρ s0 is the compacted density of concrete which setting to 2.75 g/cm 3 by reference to Riedel 8 . We get A 1 = T 1 = 30.3 GPa, A 2 = 44.1 GPa, A 3 = 31.1 GPa, B 0 = B 1 = 1.68.…”