Ballistic perforation resistance of thin concrete slabs impacted by ogive-nose steel projectiles

Martin Kristoffersen,Oda L Toreskås,Sumita Dey,Tore Børvik

doi:10.1016/j.ijimpeng.2021.103957

Abstract

Concrete is a material frequently used in protective structures exposed to extreme loading. In this study, the ballistic perforation resistance of 50 mm thick plain concrete slabs impacted by 20 mm diameter ogive-nose steel projectiles is investigated both experimentally and numerically. Three types of commercially produced concrete with nominal unconfined compressive strengths of 35, 75 and 110 MPa were used to cast material test specimens and slabs. After curing, ballistic impact tests were carried out in a compressed gas gun facility to determine the ballistic limit curve and velocity for each concrete type. Alongside the impact tests, material tests were conducted to assess the mechanical properties of the materials. Finite element models using input from the material tests were established in LS-DYNA. Here, the constitutive behaviour of the three concrete types was predicted by a modified version of the Holmquist-Johnson-Cook (MHJC) model from the literature. Numerical simulations of the ballistic impact tests were finally carried out and the results were found to be in good agreement with the experimental data. The main objective of the study is to reveal the accuracy of the MHJC model in predicting the ballistic perforation resistance of concrete slabs impacted by ogive-nose steel projectiles using standard material tests and two-dimensional digital image correlation to calibrate the constitutive relation.

Highlights

Concrete is a material frequently used for fortification installations in the process, nuclear and defence industries, where protective structure applications may not be limited by weight and space constraints [1]
Even though the concrete slabs were equipped with holes for a bolted connection to the clamping system in the impact chamber, these were not used in the ballistic impact tests
The former is confirmed by the mass loss of the concrete slabs during perforation and was observed by Dancygier and Yankelevsky [5]

Summary

Introduction

Concrete is a material frequently used for fortification installations in the process, nuclear and defence industries, where protective structure applications may not be limited by weight and space constraints [1]. Until the 21st century, most ballistic impact studies on concrete were of an empirical nature In these works, the targets were typically sepa rated into semi-infinite targets and slabs with a finite thickness. The targets were typically sepa rated into semi-infinite targets and slabs with a finite thickness The former minimises lateral boundary effects in order to study deep pene tration into massive concrete structures [2,3], while the latter aims to study projectile perforation [4,5]. From these and similar works, a number of empirical formulae [6,7] and simplified analytical models [8, 9] were established. The various damage mechanisms involved in these processes, namely compaction, compression with moderate to high lateral pressure and tensile cracking, were later discussed by Polanco-Loria et al [10], among others

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Conclusion