A Simplified ALE model for finite element simulation of ballistic impacts with bullet splash – development and experimental validation

An original simplified finite element model is proposed to simulate the effects of non-penetrating ballistic impacts causing the so-called bullet splash phenomenon (complete bullet fragmentation), while no fragmentation is caused to the target. The model is based on the Arbitrary Lagrangian Eulerian formulation (ALE) and it simulates the impact as a fluid-structure interaction. The bullet splash phenomenon has been tested by experimental analyses of AISI 304L plates impacted by 9x21 FMJ (full metal jacket) bullets. The model has been developed with the aim of creating a simplified approach to be used in the industry and forensic sciences to simulate the non-penetrating interaction of soft impactors with hard targets. Comparisons between evidence and simulation results lead to the conclusion that the proposed approach can be used in a conservative way to estimate both local and global effects of bullet-splash phenomena.

Fish Scales and Their Biomimetic Applications

Biomaterials are evolving quite rapidly over the last decade. Many applications have been considered toward their involvement in saving lives in the line of duty for law enforcement agencies and military operations. This article discusses recent work on the role of biomaterials that can be considered as a competitive alternative to composites, being used against ballistic impacts. The fish-scaled biomaterials are focused on in this paper, highlighting their excellent mechanical properties and structural configurations. In its natural environment, the scale provides fishes with an armor plating, which is significantly effective in their survival against attacks of predator and the impact inflicted from sharp teeth. These bioinspired materials, if engineered properly, can provide an excellent alternative to current Kevlar® type armors, which are significantly heavier and can cause fatigue to the human body over long-term usage. The investigated materials can provide effective alternatives to heavier and expensive materials currently used in different industrial applications. Additionally, some recent development in the usage of fish scales as a biomaterial and its applications in rapid prototyping techniques are presented. Finally, this review provides useful information to researchers in developing and processing cost-effective biomaterials.

Dynamic Impact Surface Damage Analysis of 3D Woven Para-Aramid Armour Panels Using NDI Technique

The effects of the yarn composition system inside 3D woven high-performance textiles are not well investigated and understood against their final ballistic impact behaviour. The current study aims to examine the ballistic impact performances of armour panels made of different 3D woven fabric variants through postmortem observations. Four high-performance five-layer 3D woven fabric variants were engineered based on their different warp yarn compositions but similar area density. A 50 × 50 cm2 armour system of each variant, which comprises eight nonbonded but aligned panels, namely, 3D-40-8/0 (or 8/0), 3D-40-8/4 (or 8/4), 3D-40-8/8 (or 8/8) and 3D-40-4/8 (or 4/8), were prepared and moulded to resemble female frontal morphology. The armour systems were then tested with nonperforation ballistic impacts according to the National Institute of Justice (NIJ) 0101.06 standard Level-IIIA. Two high-speed cameras were used to capture the event throughout the test. Nondestructive investigation (NDI) using optical microscopic and stereoscopic 3D digital images were employed for the analysis. The armour panels made of the 8/0 and 4/8 fabric variants were perforated, whereas the armour made of the 8/8 and 8/4 fabric variants showed no perforation. Besides, the armour made of the 8/4 fabric variant revealed higher local and global surface displacements than the other armours. The current research findings are useful for further engineering of 3D woven fabric for seamless women’s impact protective clothing.

Dynamic testing and simulation of 9 mm full metal jacket ammunition

Ballistic protection for armed forces requires a continuous performance improvement to successfully face ever evolving threats and scenarios. Ballistic tests are conventionally carried out in order to assess and validate the levels of protection to a high degree of accuracy. Although very effective, those tests are often time consuming and lack the necessary flexibility. A better approach would be to set up a numerical protocol for a number of simulations and only carry out final real life validation tests. Unquestionably, the main advantage of finite element modelling is the possibility to simultaneously evaluate a wide variety of configurations and their interactions (materials, geometry, architecture, etc.). For reliability, it is necessary to use sufficiently precise material behaviour models to accurately transcribe the phenomena observed during the impact. Our study focuses on the mechanical behaviour of 9 mm ammunition materials, namely a lead alloy core and a steel alloy jacket. For this purpose, a preliminary study (not presented here), was carried out on both the lead core and the steel jacket separately and the parameters for each constitutive model were determined. Lead-steel cylindrical samples, extracted from the ammunition, have been used for the validation of the entire constitutive model. By utilizing those samples, a high degree of the ammunitions material properties have been retained. SHPB tests have been carried out in multiple conditions, varying the striker speeds and temperatures. Additionally, the tests were recorded with an ultra-high speed camera. Strain gages were used to record signals along the input and output bars. Those measurements have been compared to numerical results using Finite Element code (ABAQUS® Explicit). A very satisfying correlation between the experimental data and the simulation has been reached, thus validating the jacket and core constitutive models and interactions for subsequent studies of ballistic impacts.

Assessment of Thorax Finite Element Model Response for Behind Armor Blunt Trauma Impact Loading Using an Epidemiological Database

Nonperforating ballistic impacts on thoracic armor can cause blunt injuries, known as behind-armor blunt trauma (BABT). To evaluate the potential for this injury, the back face deformation (BFD) imprinted into a clay backing is measured; however, the link between BFD and potential for injury is uncertain. Computational human body models (HBMs) have the potential to provide an improved understanding of BABT injury risk to inform armor design but require assessment with relevant loading scenarios. In this study, a methodology was developed to apply BABT loading to a computational thorax model, enhanced with refined finite element mesh and high-deformation rate mechanical properties. The model was assessed using an epidemiological BABT survivor database. BABT impact boundary conditions for 10 cases from the database were recreated using experimentally measured deformation for specific armor/projectile combinations, and applied to the thorax model using a novel prescribed displacement methodology. The computational thorax model demonstrated numerical stability under BABT impact conditions. The predicted number of rib fractures, the magnitude of pulmonary contusion, and injury rank, increased with armor BFD, back face velocity, and input energy to the thorax. In three of the 10 cases, the model overpredicted the number of rib fractures, attributed to impact location positional sensitivity and limited details from the database. The integration of an HBM with the BABT loading method predicted rib fractures and injury ranks that were in good agreement with available medical records, providing a potential tool for future armor evaluation and injury assessment.