Influence of Rigid Brazilian Natural Fiber Arrangements in Polymer Composites: Energy Absorption and Ballistic Efficiency

Since the mid-2000s, several studies were carried out regarding the development of ballistic resistant materials based on polymeric matrix composites reinforced with natural lignocellulosic fibers (NLFs). The results reported so far are promising and are often comparable to commonly used materials such as KevlarTM, especially when used as an intermediate layer in a multilayer armor system (MAS). However, the most suitable configuration for these polymer composites reinforced with NLFs when subjected to high strain rates still lacks investigation. This work aimed to evaluate four possible arrangements for epoxy matrix composite reinforced with a stiff Brazilian NLF, piassava fiber, regarding energy absorption, and ballistic efficiency. Performance was evaluated against the ballistic impact of high-energy 7.62 mm ammunition. Obtained results were statistically validated by means of analysis of variance (ANOVA) and Tukey’s honest test. Furthermore, the micromechanics associated with the failure of these composites were determined. Energy absorption of the same magnitude as KevlarTM and indentation depth below the limit predicted by NIJ standard were obtained for all conditions.

Ballistic Performance of Guaruman Fiber Composites in Multilayered Armor System and as Single Target

Multilayered armor systems (MAS) with a front ceramic layer backed by a relatively unknown Amazonian guaruman fiber-reinforced (Ischnosiphon koem) epoxy composites, as second layer, were for the first time ballistic tested against the threat of 7.62 mm rifle ammunition. The amount of 30 vol% guaruman fibers was investigated in three distinct configurations: (i) continuous aligned, (ii) 0–90° cross-laid, and (iii) short-cut randomly dispersed. Additionally, single-target ballistic tests were also carried out in the best MAS-performed composite with cross-laid guaruman fibers against .22 caliber ammunition. The results disclosed that all composites as MAS second layer attended the US NIJ standard with corresponding penetration depth of (i) 32.9, (ii) 27.5, and (iii) 29.6 mm smaller than the lethal limit of 44 mm in a clay witness simulating a personal body. However, the continuous aligned guaruman fiber composite lost structural integrity by delamination after the 7.62 projectile impact. By contrast, the composite with cross-laid guaruman fibers kept its integrity for subsequent shootings as recommended by the standard. The single-target tests indicated a relatively higher limit velocity for .22 caliber projectile perforation, 255 m/s, and absorbed energy of 106 J for the cross-laid guaruman fibers, which are superior to corresponding results for other less known natural fiber epoxy composites.

Ballistic Performance of Sandwich Composite Armor System

This study focused on the design, modelling and the analysis of the dynamic response of composite armor system, constructed with Kevlar 29 as front skin, Alumina-ceramic filled in x shaped corrugated structure as core and bottom skin Kevlar 29 and T800S, in terms of residual velocity, energy absorption capacity and limiting velocity. The core cell size, height, thickness, skin thickness, etc., will be varied to get their influence on the impact resistance. The design parameter will be investigated for the sandwich composite armor with various configurations and stacking sequence of Alumina Ceramics, Kevlar 29 and T800S. The sandwich typically consists of front plate, core and backing plate, which will be impacted at different velocities starting at 100m/s till significant armor penetration. The ballistic limit velocity (V50) will be determined from the analysis. The non-linear explicit dynamic analysis and simulation results computed using the software ABAQUS will be validated by experiment. From the data obtained it can be suggested which composite armor has improved impact resistance and performance.

Composites with Natural Fibers and Conventional Materials Applied in a Hard Armor: A Comparison

Natural-fiber-reinforced polymer composites have recently drawn attention as new materials for ballistic armor due to sustainability benefits and lower cost as compared to conventional synthetic fibers, such as aramid and ultra-high-molecular-weight polyethylene (UHMWPE). In the present work, a comparison was carried out between the ballistic performance of UHMWPE composite, commercially known as Dyneema, and epoxy composite reinforced with 30 vol % natural fibers extracted from pineapple leaves (PALF) in a hard armor system. This hard armor system aims to provide additional protection to conventional level IIIA ballistic armor vests, made with Kevlar, by introducing the PALF composite plate, effectively changing the ballistic armor into level III. This level of protection allows the ballistic armor to be safely subjected to higher impact projectiles, such as 7.62 mm caliber rifle ammunition. The results indicate that a hard armor with a ceramic front followed by the PALF/epoxy composite meets the National Institute of Justice (NIJ) international standard for level III protection and performs comparably to that of the Dyneema plate, commonly used in armor vests.

Ballistic behavior of multilayer wire mesh application armor

In this paper, an attempt was made to increase the ballistic protection of the armor system by combining non-homogenous spaced armor in form of multilayer wire mesh with rolled homogenous armor steel base plate. Different angles of incidence were tested: 0, 20, 25 and 35o, by using 12.7 mm armor piercing incendiary ammunition from 100 m. It was found that the inclination of the armor system has a negative effect on ballistic resistance due to variations in wire body-to-body distance, some of which can increase, causing a decreased contact with the projectile and an insufficient yaw. The yaw causes a sideways impact on the base plate. However, the non-penetrating hits in vertical armor cause a more severe damage on the base plate compared to the inclined armor system. This effect is due to the inclination itself, which is a common behavior of increasing effectiveness of sloped armor.

Impact Analysis of a Composite Armor System

Present day demands composite material with even lighter weight and higher strength for using in aerospace, automobile and defense industries. Due to posing significantly weight saving and higher stiffness attribute, use of sandwich composite structure is the demand of the time. Impact analysis of sandwich composite armor system is necessary to design and develop new armor for defense sectors. The goal of this study is to design, model and analyze the dynamic response of the composite armor system in terms of residual velocity and energy absorption capacity. The design parameters are investigated for different fiber reinforced polymers (High tensile strength Carbon/epoxy, Carbon Fiber/Carbon Nanotube reinforced polymers) as top and bottom skin, with an Aluminum Alloy 7039 corrugated core structure and square prismoid assembled Ceramic (SiC) core centerpieces at different velocities (50 m/s, 100 m/s, 200 m/s, 400 m/s). This non-linear explicit dynamic study is performed using commercial software ABAQUS CAE 2017. Best combination for the composite armor system is suggested based on the results.