Experimental Development of a Constitutive Model for High-Speed Impact Containment Fabrics (original) (raw)
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Finite Element Modeling of Ballistic Impact on Multi-Layer Kevlar 49 Fabrics
This paper presents a material model suitable for simulating the behavior of dry fabrics subjected to ballistic impact. The developed material model is implemented in a commercial explicit finite element (FE) software LS-DYNA through a user defined material subroutine (UMAT). The constitutive model is developed using data from uniaxial quasi-static and high strain rate tension tests, picture frame tests and friction tests. Different finite element modeling schemes using shell finite elements are used to study efficiency and accuracy issues. First, single FE layer (SL) and multiple FE layers (ML) were used to simulate the ballistic tests conducted at NASA Glenn Research Center (NASA-GRC). Second, in the multiple layer configuration, a new modeling approach called Spiral Modeling Scheme (SMS) was tried and compared to the existing Concentric Modeling Scheme (CMS). Regression analyses were used to fill missing experimental data – the shear properties of the fabric, damping coefficient and the parameters used in Cowper-Symonds (CS) model which account for strain rate effect on material properties, in order to achieve close match between FE simulations and experimental data. The difference in absorbed energy by the fabric after impact, displacement of fabric near point of impact, and extent of damage were used as metrics for evaluating the material model. In addition, the ballistic limits of the multi-layer fabrics for various configurations were also determined.
Finite Element Modeling of Ballistic Impact on Kevlar 49 Fabrics
This paper presents an improved material model suitable for Kevlar 49 fabric which was implemented into the commercial explicit Finite Element (FE) software LS-DYNA through a user defined material subroutine (UMAT). The fabric constitutive behavior in the current material model was obtained from new experimental data in the principal material directions (warp and fill) under static loading. Two different modeling configurations, i.e. single FE layer and multiple FE layers were used to simulate the ballistic tests conducted at NASA Glenn research center. Both the shear properties of the fabric and the parameters used in Cowper-Symonds (CS) model which accounts for strain rate effect on material properties were optimized to achieve close match between the FE simulations and experimental data. The residual velocity of the projectile, the absorbed energy by the fabric after impact, and the temporal evolution and the spatial distribution of the fabric deformation and damage were closely examined. Sensitivity analysis was carried out to study the effect of the failure strain of the fabric and the coefficient of friction on the simulation results.
Influence of boundary conditions on the ballistic performance of high-strength fabric targets
International Journal of Impact Engineering, 2005
High-strength fabric is commonly used in personnel protection systems against small arms projectiles and fragments. An understanding of the characteristics of high-strength fabric under ballistic impact would provide useful insights for fabric armor design. A numerical model is formulated and used to study the perforation of square cross-woven fabric targets when the fabric is (i) clamped along all four edges with its yarns aligned parallel to the edges, (ii) clamped along all four edges with yarns running 451 to the edges and (iii) clamped along two edges with yarns aligned parallel to the edges. In addition, high-speed ballistic tests are carried out to validate the computational results. It is found that the ballistic resistance of such systems is sensitive to boundary conditions and yarn orientation. Targets that are unclamped on two edges can absorb more impact energy than those with all four sides clamped. Orientating the yarns 451 to the clamped edges can improve energy absorption significantly. Stresses in primary yarns (those in contact with the projectile) increase rapidly when their ends are clamped; this leads to rapid failure at the impact point and a lower-energy absorption. For fabrics clamped along four edges, the regions near the four corners are not stretched during impact if the yarns are parallel to the edges, whereas clamping with the yarns 451 to the edges facilitates energy dissipation by the entire fabric. It is also observed that slippage at clamped edges contributes to higher energy absorption by fabric targets.
Effects of architecture on ballistic resistance of textile fabrics: Numerical study
International Journal of Damage Mechanics, 2013
Composite textiles composed of materials such as Kevlar, Dyneema and Zylon are extensively used in many force/impact protection applications, such as body armor, and automobile and airplane engine fragment resistant containment. Significant effort has been devoted to ballistic testing of composite fabrics made from various manufacturing processes and designs. Performing comprehensive ballistic and impact tests for these composite textiles is a very time-consuming and costly task. Numerical models are presented in this research, thereby providing predictive capability for the manufacturer and designer to minimize field testing, as well as shedding light on to the damage mechanisms of composite fabrics subjected to ballistic impact. Several representative composite fabric architectures (such as plain weave, basket weave and knitted fabrics) are generated for finite element analysis. Numerical investigation is conducted on these fabric structures of the same mass per unit area subjected to projectile impacts. Failure patterns of woven and knitted fabrics obtained from numerical simulations are compared with those observed experimentally. Performances of the representative textile structures are evaluated based on the resultant velocity of the projectile, as well as various energy components. The influences of yarnyarn and yarn-projectile friction properties on the ballistic performance of various textile structures are presented. To highlight the effects of projectile geometry and angular rotation on the fracture of woven and knitted fabrics, a series of simulations are also performed with three distinctive projectiles of the same mass and impact energy.
2009
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The United States Government assumes no liability for the contents or use thereof. The United States Government does not endorse products or manufacturers. Trade or manufacturer's names appear herein solely because they are considered essential to the objective of this report. This document does not constitute FAA certification policy. Consult your local FAA aircraft certification office as to its use. This report is available at the Federal Aviation Administration William J. Hughes Technical Center's Full-Text Technical Reports page: actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF).
Effect of Textile Architecture on Energy Absorption of Woven Fabrics Subjected to Ballistic Impact
Applied Mechanics and Materials, 2014
Woven fabrics are widely used in various protective applications. The effects of different woven architectures (such as plain, basket, twill and satin) on impact resistance performance have not been adequately studied. In this work, high-speed impact testing on single layer plain weave structures has been carried out using a gas gun experimental setup. Ballistic resistance performance of the woven fabric is evaluated based on the resultant velocity of the projectile, as well as the post-mortem failure analysis. Finite element computational models are presented in this research, thereby providing predictive capability for the manufacturer and designer in order to minimise field testing, as well as shedding light on to the damage mechanisms of composite fabrics subjected to ballistic impact. The numerical model is validated with the experimental results in terms of dissipated energy and resultant velocity. Numerical investigation is conducted on other woven structures of identical areal density for comparison, revealing the importance of fabric architecture. The influences of yarn-yarn and yarn-projectile friction properties on the ballistic performance of various textile structures are also presented.
International Journal of Impact Engineering, 2007
The early impact behaviour of single and multi-ply Kevlar s 129 fabric armour systems is investigated using an explicit finite element code, TEXIM, developed in-house. This numerical model is carefully validated using continuous temporal data obtained from an instrumented experimental setup. The model is then used to explore the loss in ballistic efficiency of woven fabric targets, as experienced early in the impact event, when either the number of layers in the panel or the yarn denier is increased. r (R. Vaziri).
IJERT-Ballistic Impact Resistance Mechanism of Woven Fabrics and their Composites
International Journal of Engineering Research and Technology (IJERT), 2016
https://www.ijert.org/ballistic-impact-resistance-mechanism-of-woven-fabrics-and-their-composites https://www.ijert.org/research/ballistic-impact-resistance-mechanism-of-woven-fabrics-and-their-composites-IJERTV4IS120160.pdf The development of the new generation of tough, high-strength, high-modulus fibers has led to the use of fabrics and their composites for a number of ballistic protection applications, in particular, for body armor. Numerous studies have been conducted to identify material properties and ballistic impact resistance mechanism that are important to the performance of ballistic fibers and their composites. The paper reviews the factors that influence ballistic performance including mechanisms of ballistic impact resistance, specifically, material properties of the yarn, fabric architecture, projectile geometry and impact velocity, boundary conditions, multiple plies and friction effect. It is important to note that almost all of the parameters that affect ballistic penetration resistance of a fabric are interrelated and the attempts to single out an individual effect cannot lead to a conclusive result. This makes the studies very complicated.
Characterization of the dynamic behavior of yarns for the modeling of ballistic fabrics
The use of fabrics as part of ballistic protections is widely spread since 70's. The development of these new ballistic solutions needs numerical simulations, in order to predict the performance of the ballistic protection and the potential secondary effect. The performances and the induced mechanisms in ballistic fabrics during an impact depend on the weaving parameters and also on inner parameters of yarns used in these structures. Thus, knowing the dynamic behavior of yarn is essential to determined the ballistic behavior of fabrics during an impact. For this purpose, we use four experimental setups in order to reveal dynamic parameters of ballistic yarn during high speed mechanical stress.