Papers by Keyword: Ballistic Protection

Abstract: Titanium-based materials are attractive candidates to make low-weight armor parts. However, a broad use of titanium is limited by its high cost, especially when traditional cast and wrought technology is in place. This issue requires more economical production and improved protective properties of titanium-based materials. Powder metallurgy is a valid alternative to make products less expensive, especially when low-cost hydrogenated titanium is used instead of high-quality titanium powder. For effective protection, titanium-based armor should exhibit a substantially improved combination of hardness, strength and ductility, which can be achieved by using laminate (layered) structures. In this study, laminates based on Ti-6Al-4V (wt.%) alloy and its composites reinforced with light and hard particles of TiC and TiB were made using blended elemental powder metallurgy of hydrogenated titanium. Simplest press-and-sinter option as well as additional hot isostatic pressing were tested to achieve high set of characteristics of individual layers and laminates as a whole. It has been shown that the used reinforcement presents an exceptional opportunity for hardening of Ti-based composites without compromising their low specific weight and capable of hardness increase by more than 40% compared to the base alloy. Fabricated structures were ballistic tested and compared with open data on commercial armor made of titanium.

Abstract: The main aim of this paper is to study and analyze methods of predicting the serviceability and lifespan of ballistic armors made of a high-strength polyethylene ultra-high molecular weight (UHMWPE) fibers composites. Experimental tests were conducted on the accelerated use of composite ballistic inserts in lab to predict the durability; changes in the ballistic, physical, and mechanical properties occurring due to accelerated conditions of use. Data of following ageing simulation methods under controlled environment was used. 1-Application of mechanical load to the insert, 2-application of mechanical load and temperature cycle treatment to the product and 3-applying mechanical load, temperature cycle and immersion in liquid solution simulating human sweat to the test product. It was revealed that mechanical loading, temperature cycling, and the solution simulating human sweat incites the degradation and disintegration of the polyethylene material. To evaluate the correlation between the natural ageing process and the simulated one, ballistic insert samples were also examined under natural conditions for 5, 7, 9 and 13 years. Ansys Workbench Explicit Dynamics (R1 2020) and Solidworks (2018) were used to model and simulate the ballistic impact on standard product as well as accelerated aged samples. Experimental testing data was used in simulation and results were compared to analyze the ageing behavior of composite armor.

Abstract: This paper describes the outcomes of practical experiments in the validation of a technology for welding of the Al-Al₂O₃ metal-matrix composite material produced by the internal oxidation method. Technological capabilities are herein considered for argon-arc welding (Tungsten Inert Gas/ TIG) with filler wire and arc welding in a protective inert/active gas medium using a melting electrode (Metal Inert Gas/ MIG) for joining sheets of A6 aluminum alloy-based metal-matrix composite material (MMC). Mechanical properties of welded joints are determined and the fracture macrostructure is investigated. Fracture patterns and tensile strength are shown for different modes of welding procedure for alloy plates of 5, 8 mm in thickness by the TIG method and 25 mm by the MIG method. The macrostructural and mechanical heterogeneity of welded joints is shown. Welds made under optimal conditions are free of any macrodefects. The welded joint strength is up to 96% of the base material strength.

Abstract: In this paper a possibility of application of disperse-strengthened composite aluminum material as a ballistic protection is discussed. Experimental results of tests with bullet (PAB-9) are presented. Experiments were carried on with alloy based on A6 strengthened with aluminum oxide (Al₂O₃) particles. We present the experimental result of the development of welding technology of disperse-strengthened alloy Al-Al₂O₃ obtained with internal oxidation method. It was shown that under optimal conditions welding seam are free from macro-defects. We showed that the disperse-strengthened composite material as a part of ballistic protection exhibit significant increase of resistance against bullet penetration. This composite material can be used in structural elements because it does not suffer from destruction as opposed to ceramic materials. Mentioned above properties makes disperse-strengthened composite aluminum alloy a promising material for ballistic protection.

Abstract: Different types of composite materials with potential application in ballistic protection of static objects are discussed and compared in present study. The studied solutions include: 1) the concretes with or without reinforcement, 2) the metallic boxes with internal gap filled with different materials and 3) the ceramics-metallic composite armours. Besides the ballistic resistance, the areal weight and the price are taken into account. The weight of solutions is important in case of static objects mainly from logistic point of view. The proposals of ballistic compositions presented in the study can facilitate the choice of solutions according to specific requests.

Abstract: This paper presents some experimental results of a bullet impact on composite armor together with numerical modeling approaches. The development of light composite sandwiches for ballistic protection is the target of a project in terms of which the research is being conducted. Traditionally, a vehicle ballistic protection is mainly achieved through metal-based armor which is extremely heavy, hence the increasing popularity of composite sandwiches. Numerical simulations allow for a reduction of the number of experiments needed to obtain appropriate design of ballistic protection, but they require verified modeling approaches and proper material data. Therefore, different modelling approaches for both parts of the composite sandwich have been tested and possibilities to adjust these models to experimental data were investigated.

Abstract: The work presented in this paper concerns a project on the optimization of protections subjected to explosions (IED’s threat). Explosions generate two types of threats for a protective structure: blast and impact of fragments. Perforating and non-perforating impact tests were performed in our laboratory with steel spherical projectiles impacting a target based on Kevlar^® textile layers and a crushable material, Crushmat^®. These tests required to develop a specific experimental test setup in order to contain the composite protective structure and to be able to measure the relevant parameters. The experiments allow us to determine the ballistic performance and basic parameters of the protection, and to validate finite element numerical models (LS-DYNA) resulting in a performant prediction tool. The approach used for the simulation consists in the representation of the full textile architecture with solid elements. Therefore, the textile material is explicitly represented in the model in order to have a good representation of the physical phenomena occurring during impact. For the crushable material, a representation using SPH was chosen in order to take the granular behaviour of this material into account. Good results are obtained with such models. However, these models are very complicated and computing time consuming. The geometry has to be well adapted and symmetry has to be exploited. On the other hand, representation of a granular material with SPH does not take into account some characteristics of this material during impact, such as the pulverisation process of the granular material. Solutions to take these phenomena into account in the model are proposed.

Abstract: The paper presents a numerical study of a double layer composite panels impacted by a AP (Armor Piercing) 51WC projectile. The standard panel is built with aluminum and Al2O3 ceramic continuum layers while the studied model consists of the same aluminum plate but the front one is built with a set of hexagonal ceramic bars. The bar width and the impact position influence on the ballistic resistance are analyzed and compared with the reference solution. The problem has been solved with the usage of the modeling and simulation methods as well as finite elements method implemented in LS-DYNA software. Space discretization for each option was built by three dimension elements guarantying satisfying accuracy of the calculations. For material behavior simulation specific models including the influence of the strain rate and temperature changes were considered. Projectile Tungsten Curbide and aluminum plate material were described by Johnson-Cook model and ceramic target by Johnson-Holmquist model. In the studied panels the area surrounding back edges was supported by a rigid wall. The obtained results show interesting properties of the examined structures considering their ballistic resistance. All tests has given clear results about ballistic protection panel response under WC projectile impact. Panels consisting of sets of hexagonal ceramic bars are slightly easier to penetrate, reference model is stronger by 19% for smaller bars and by only 7% for bigger rods. Despite this fact, the ceramic layer is much less susceptible to overall destruction what makes it more applicable for the armor usage. Furthermore, little influence of the projectile impact point and consequently a part of the bar which is first destroyed is proved.

Abstract: Numerical investigations were performed to determine the influence of the spherical convex shape ceramic - alumina composite in reference to the standard double layer panel. All versions of the target were verified in an impact test including influence upon the position of the AP (Armor Piercing) 7,62x51HHS impact. The crucial parameter which was used for this verification was change in time of the PROJECTILE kinetic energy. The problem has been solved with the usage of the modeling and simulation methods as well as finite elements method implemented in LS-DYNA software. Space discretization for each option was built by three dimension elements guarantying satisfying accuracy of the calculations. For material behavior simulation specific models including the influence of the strain rate and temperature changes were considered. Projectile’s core made of HHS and aluminum plate material were described by Johnson-Cook model and ceramic target with Johnson-Holmquist model. In the studied panels the area surrounding back edges was supported by rigid wall. The obtained results show interesting properties of the new structures considering their ballistic resistance. However only certain places were chosen for tests, the protection ability against projectile attack is in general higher than the reference model. What is particularly interesting during the 6.6mm from the sphere center impact the sphere surface trajectory deviation effect is present. A projectile is not stopped here by material strength but the front layer shape. Moreover it can be assumed that this phenomenon will take place on majority of points on the sphere surface. Despite this fact, a ceramic multi sphere layer is less susceptible to overall destruction, depending on the impact point. The results of those numerical simulations can be used for designing of modern armor protection systems against hard kinetic projectiles.