The Lattice Discrete Particle Model (LDPM), a meso-scale model for concrete, was extensively calibrated and validated in previous research for quasi-static loading conditions. In this paper, LDPM is used to investigate the time-dependent behavior of concrete for high strain rates with the main objective of (1) assessing the role of apparent and intrinsic rate effect mechanisms on the macroscopic concrete response; and (2) demonstrating LDPM predictive capabilities under dynamic loading conditions. The LDPM formulation is extended to incorporate rate-dependent fracture mechanisms associated with the interpretation of fracture processes as thermally activated phenomena and governed by the classical Maxwell-Boltzmann theory. According to this approach, the LDPM meso-scale strength and toughness are assumed to be functions of the meso-scale strain rate. The model is calibrated and validated on the basis of experimental data available in the literature and obtained through (a) reinforced and unreinforced unconfmed compression tests; and (b) Hopkinson bar tests in tension and compression. Analysis of the numerical results shows the ability of LDPM to simulate accurately the dynamic response of concrete under a large variety of loading conditions. Furthermore, in this study, LDPM is used to perform simulations of projectile impacts on regular strength concrete (RSC) and high strength concrete (HSC). Perforation and penetration experiments on RSC and HSC for varied impact velocities are carried out and the exit velocities are compared to available experimental data. In general, LDPM replicates successfully the behavior of concrete for penetration and perforation events and it is able to capture accurately the main features of concrete response in terms of projectile deceleration as well as fracture patterns.
展开▼
