This paper reviews the topic of ballistic impact of dry woven fabric composites. It highlights previous work done in modeling the fabrics and the theory involved. Attention is also given to experimental testing, ballistic penetration resistence, projectile characteristics, and failure modes in yarns and fabric. Concepts to further enhance the ballistic penetration resistance of woven fabrics are discussed. This paper serves as an effective source of literature for those interested in conducting research into this topic. Altogether, 176 references have been cited to allow further investigation.
SUMMARYThis work presents a computational material model of exible woven fabric for ÿnite element impact analysis and simulation. The model is implemented in the non-linear dynamic explicit ÿnite element code LSDYNA. The material model derivation utilizes the micro-mechanical approach and the homogenization technique usually used in composite material models. The model accounts for reorientation of the yarns and the fabric architecture. The behaviour of the exible fabric material is achieved by discounting the shear moduli of the material in free state, which allows the simulation of the trellis mechanism before packing the yarns. The material model is implemented into the LSDYNA code as a user deÿned material subroutine. The developed model and its implementation is validated using an experimental ballistic test on Kevlar J woven fabric. The presented validation shows good agreement between the simulation utilizing the present material model and the experiment.
This paper presents two newly developed micromechanical models for the analysis of plain weave fabric composites. Both models utilize the representative volume cell approach. The representative unit volume of the woven lamina is divided into subcells of homogeneous material. Starting with the average strains in the representative volume cell and based on continuity requirements at the subcell interfaces, the strains and stresses in the composite fiber yarns and matrix are determined as well as the average stresses in the lamina. Equivalent homogenized material properties are also determined. In their formulation the developed micromechanical models take into consideration all components of the three-dimensional strain and stress tensors. The performance of both models is assessed through comparison with available results from other numerical, analytical, and experimental approaches for composite laminae homogenization. The very good accuracy together with the simplicity of formulation makes these models attractive for the finite element analysis of composite laminates.Here a single superscript f is used to denote that the corresponding quantity refers to the fill yarn, and w refers to the warp yarn. Fig. 2 Geometry of the quarter cell for the four-cell model
SUMMARYNumerical simulation of cracked structures is an important aspect in structural safety assessment. In recent years, there has been an increasing rate of development of numerical codes for modelling fracture procedure. The subject of this investigation is implementing automated fracture models in the DYNA3D non-linear explicit ÿnite element code to simulate pseudo 3D crack growth procedure. The implemented models have the capabilities of simulating automatic crack propagation without user intervention. The implementation is carried on solid elements. The methodology of implementing fracture models is described. An element deletion-and-replacement remeshing procedure is proposed for updating the explicit geometric description of evolving cracks. Fracture parameters such as stress intensity factors, energy release rates and crack tip opening angle are evaluated. The maximum circumferential stress criterion is used to predict the direction of crack advancement. Seven crack problems are presented to verify the e ectiveness of the methodology. Mesh sensitivity and loading rate e ects are studied in the validation of the presented procedure.
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