Papers by Keyword: Armor

Abstract: The trade-off between strength and toughness remains a major challenge in structural materials engineering, especially for titanium-based materials. This study explores the potential of titanium-based laminates for lightweight armor, aimed at improving anti-ballistic properties through the use of layered structures. Titanium alloy Ti-6Al-4V (Ti64) was combined with metal matrix composites (MMCs) reinforced with TiC or TiB particles (up to 40 vol%) using two powder metallurgy (PM) techniques. The first approach used press-and-sinter blended elemental powder metallurgy (BEPM) to create the laminates in a single step, while the second involved post-processing via hot isostatic pressing (HIP) to enhance material properties. Both fabrication methods produced laminates that significantly outperformed commercial alternatives in ballistic testing against 7.62 mm armor-piercing bullets. The use of HIP post-BEPM enhances material properties by reducing porosity and increasing hardness, highlighting the complementary nature of these technologies in producing efficient and cost-effective armor materials.

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: 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: The Development of Fiber Reinforced Plastics (FRP) offers a great opportunity for applications in automobile industry, aeronautics and consumer goods to achieve light weight structures. However, the connection technology between FRP and mainly metallic based structures is the key to use the full potential of the FRP. Out of this motivation recent developments address this aspect.Using the powder metallurgical approach to generate a metal/ FRP connection module by spark plasma sintering a great variety is possible by integration of different metal and/ or fiber components. In this work aluminum and stainless steel was chosen for the upper and lower metallic side. The fibers integrated into the metal were glass, basalt and carbon fiber in one layer, two layer and mixed layer configuration. To connect the sintered module to greater CF weaves an infiltration process with a room temperature curing resin was used in a modified vacuum infusion (MVI) setup. In not optimized configuration the shear test after infiltration indicated an initial value for module shear strength above 20 MPa which can be enhanced in future developments by optimized armor between the upper and lower metal side and the number of integrated fiber layers of the connection module. A model is predicted to calculate the module shear strength in sintered state by multiplication of the armor area with the shear strength of the armor material. First experiments additionally show the possibility to weld the connection module directly to metallic structures.

Abstract: In this work, the shaped charge jet formation depends on different parameters which can has effect on jet behavior such as jet velocity, breakup and penetration. Jet radius or liner thickness, shell thickness, liner material density, α angle and stand-off distance are evaluated in purpose to investigate their effect on performance of shaped charge jet velocity and jet breakup phenomena, also we investigate the effect of stand-off distance on shaped charge jet penetration into steel target. We also studied the performance of some protective shields materials in order to assure more protection for vehicle structure against shaped charge jet penetration. For that, different materials were used as armors such as: kevlar epoxy, polyethylene, glass epoxy, steel-1006 and Al₂O₃ ceramic. These protective shields were evaluated in order to show their performance against shaped charge penetration into target. To do so, adopted explicit dynamic analyzing program Autodyn basing on finite element were used to simulate shaped charge jet formation and penetration. Autodyn-2D simulationshighlight the efficiency of our work comparing with the experiments done in literature and Birkhoff’s theory. In other terms, increasing in shell thickness, alpha angle and liner densityenhance jet breakup time, protective shields layered armor of steel-1006, steel 1006 with polyethylene and steel-1006 with Al₂O₃ceramic give more protection for structure against shaped charge jet penetration comparing with others armors.

Abstract: The paper presents research conducted in order to achieve some self-shielding armor with high and pre-established strength to intense wear abrasion combined with corrosion, in damp environment, with sulfur content, at temperatures up to 500°C. The first stage was dedicated to the elaboration of the concept of armor and the hardfacing technology, using a hyper-entropic filler metal which assures a self-protection characteristic. The samples used in the experiment were mild steel plates covered with weld in the rhomboid form. In the next stage some investigations were conducted in order to manufacture of new welding materials such as Fe-22%Cr-Mo-V deposited by welding in certain circumstances, having the hardness after welding about 30 HRC. This weld deposit becomes harder after a short working time, having average hardness value of 55 HRC. In stage three some exploratory research was done in order to establish the welding parameters for obtaining the self-protection layers of hyper-entropic material. In the final stage the armor element achieved was tested, to determine performance characteristics during working into the mill fan. After 2 weeks, some samples were sectioned in order to measure the hardening effect during working.

Abstract: Welding steel armor reduces the armor materials protection capability. Several industrial and military welding standards exist for welding armor materials with the primary focus on joint strength rather than ballistic integrity.The Heat Affected Zone (HAZ) created by the welding process introduces vulnerabilities in the protection system. The process and designs that we have demonstrated include mitigation features that eliminate the ballistic degradation and provide uniform protection across all armor materials.In this study we used finite element simulation of the welding process to perform trade studies evaluating welded joint designs, and to show how the designs could be altered to both optimize armor performance and reduce welding heat input. A beneficial effect of reduced heat input was the corresponding reduction in welding-induced residual stresses, an overall reduction in assembly distortion in the assembly, and improvement of the armor performance.The simulated welding process included the creation of the heat affected zone and the development of residual stresses in the structure. ABAQUS finite element software was used for the simulation with the aid of an extensive material property database created over the wide range of welding temperatures.The finite element simulation predictions were validated and verified with excellent results by metallography and micro-hardness measurements. Live-fire ballistic tests were used as the final proof of measurable design improvements. Finite element welding simulation was shown to be an effective tool for improving upon standard welded armor designs, and above all in improving human safety.

Abstract: Based on the understanding of material characteristics and interaction between projectile and target, a lightweight hybrid composite armor target consisting of alumina ceramics pellets and ultrahigh molecular weight polyethylene (UHMWPE) was designed and prepared. The target areal density of the armor panel was 7.5 g/cm². The standard size of the armor panel was 150mm×150mm×43mm. The Ballistic Performance of Alumina/UHMWPE composite armor against an impact of 12.7 mm armor piercing (AP) projectile was investigated at the nominal velocity of 818 m/s. The energy absorbing mechanism revealed that the armor was able to protect against the projectile, together with weight saving.

Abstract: New ballistic protection systems based on alternative materials have been recently developed. One of the industry’s objectives is to develop lighter and stronger defensive systems, which allow higher mobility and safety for both vehicles and humans. This work studies the behavior of an aerospace protection against a projectile impact, seeking an optimized construction. The Al-Qureshi et al. model suggests a ceramic-metal layer system and describes its behavior. The literature shows, due to the considered parameters, the erosion tax and the loss of velocity. The phenomenon is described in steps, presenting particular effects for each. The equations are not equal between the stages showing different properties. The present work searches for a solution that can show the expression for mass and velocity, for each stage of the phenomenon. The results from the numerical method used were plotted and analyzed. The treatment was performed using Maplesoft Maple software. As a result, graphs were generated, which allow a deeper analysis of the model. Finally, advance in the knowledge of fracture processes in materials by high velocity impact can be concluded. This fact permits developments in materials that can perform shock absorption.

Abstract: Monolithic ceramic tile is used as part of ceramic-composite armor. Rejection of individual tile that contain potential threat-defeat-reducing ―defects‖ must be accomplished in a fast and cost-effective manner. Water-immersion phased-array ultrasound using 10 MHz 128-element transducers sequenced at 32-elements has been demonstrated to quickly scan and detect 25-50 um known inclusion-type defects in individual 25 mm thick SiC tile. Further, use of similar phasedarray transducers and similar transducer-element activation sequences, has shown detection of intentional internal defects in tests of 40 cm square by 50 mm thick, multi-layered composite ceramic-armor specimens. Large changes in acoustic velocities of the various layered materials causes focusing issues of the ultrasonic wave. The use of various digital signal processing methods can be used to overcome some of these issues. The results show that use of phased array ultrasound can reliably be used for defect detection in either monolithic or composite ceramic-armor. The technology and various results are presented.