Experimental and numerical investigation on penetration of clay masonry by small high-speed projectile

Abstract

This study investigates a kind of masonry consisting of clay-fired brick (fc = 10 MPa; ρ=1.38g/cm3) and mortar (fc = 10 MPa; ρ=1.8g/cm3). Clay-fired brick masonry connotes a traditional construction material of old architecture and public buildings. We carried out penetration experiments in which four clay-fired brick walls employing two different patterns were subjected to impact from small high-speed projectile, i.e. 12.7 mm armor-piercing explosive incendiary projectile and material tests in which the static and dynamic compressive strengths of clay-fired brick and mortar were determined by quasi-static and SHPB (Split Hopkinson Pressure Bar) tests. The experimental data include hit and exit velocities, damage configuration of clay brick masonry and mechanical properties of material at low and high strain rates, though which influence of thickness and bonding patterns of wall on kinetic loss of bullet, the damage patterns of masonry observed experimentally and dynamic increase of material strengths are analyzed. To keep minimum boundary inconsistency with reality, full 3D detailed finite element model consisting of two different material is established. Sharing common nodes and employing automatic tiebreak contact are combined to reduce computational time usage of large-scale model. For description of clay-fired brick and mortar Riedel–Hiermaier–Thoma (RHT) material model is employed. Material parameter set is derived based on experimental data, available literature and engineering assumptions. The numerical simulations study the mesh resolution dependency of material model, reproduce the crucial phenomena of masonry in experiment acceptably and offer more time-resolved insight into motion of bullet in the process of penetration. The feasibility of means of constructing finite element model and applying RHT model to the masonry herein and analogous constructions is explored through numerical investigation.