Ballistic impact on fired clay masonry bricks

Abstract

We perform an experimental and numerical study of ballistic impact on the German fired clay brick material VMz28. Parameters for the concrete material model applied in hydrocode simulations stem from material characterization experiments, especially planar plate impact experiments, engineering assumptions, and parameter studies. The performance of the numerical model is illustrated by a comparison of its results to ballistic data on penetration and perforation of spherical steel projectiles. Agreement is found between experiment and simulation for residual velocities and penetration depths. The experimental damage patterns are reproduced in the simulation with sufficient agreement. The application of the model to the impact of another differently shaped generic projectile reveals good predictive capabilities in a part of the impact velocity range. For the deviation found in the other part, limitations of the model concerning the full reproduction of the observed spall failure are discussed as a possible explanation. Overall, with moderate experimental effort, a numerical model with reasonably good predictive capabilities is obtained for engineering purposes.

Hugoniot Data and Equation of State Parameters for an Ultra-High Performance Concrete

“…In each series, eight successful experiments with different impact velocities have been conducted. For all of these curves, the expected features for an inverse PPI test with a porous material are present in the data [27,32,34,35]. Explicitly, each curve shows a first Hugoniot plateau, several release plateaus, and a backing reflection.…”

“…Figure 1 illustrates the experimental setup of both series schematically. In principle, the experiments in this work are analogous to former investigations on concrete [27], sandstone [32], adobe [34], and masonry brick material [35]. In all cases, the specimen was bonded to a backing plate with a two component epoxy, then the Fig.…”

“…In the following, the setup of two experimental series, mainly differing by the employed plate materials C45 steel and aluminum 7075 T6, are presented. The former has been used in previous own studies [27,30,32,34,35] while the latter is a rather novel material for our PPI experiments. One reason for the choice of aluminum is that its shock impedance is sufficiently high to be used in inverse PPI experiments with concrete: the density of Al 7075 T6 is slightly higher (> 10%), while the wave velocity clearly exceeds (> 50%) that of concrete.…”

“…The Hugoniot elastic limit of u HEL,steel = 36 m/s of the current C45 steel lot corresponds to the elastic precursor signals visible in the free surface velocity time curves. In earlier works [27,30,32,34,35] a hardened C45 steel with a higher yield strength and hence a larger value for u HEL,steel has been used. For Al 7075 T6, the corresponding constants are ρ Al = 2.804 g/ cm 3 , S Al = 1.36, c B,Al = 5200 m/s, u HEL,Al = 160 m/s, and c p,Al = 6300 m/s for all u fs_2 values [45].…”

“…The planar plate impact (PPI) test is an established technique to investigate EOS properties under shock loading [13,20,21] that has been applied to a variety of different materials, such as metals, composites, concretes and geomaterials [15,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Hugoniot data derived from these experiments is available for different types of concrete [15, 22-25, 27, 29] and mortar materials [27,31,33].…”