Meso-FE modelling of textile composites: Road map, data flow and algorithms

Disorder and long-range interactions are two of the key components that make material failure an interesting playfield for the application of statistical mechanics. The cornerstone in this respect has been lattice models of the fracture in which a network of elastic beams, bonds, or electrical fuses with random failure thresholds are subject to an increasing external load. These models describe on a qualitative level the failure processes of real, brittle, or quasi-brittle materials. This has been particularly important in solving the classical engineering problems of material strength: the size dependence of maximum stress and its sample-to-sample statistical fluctuations. At the same time, lattice models pose many new fundamental questions in statistical physics, such as the relation between fracture and phase transitions. Experimental results point out to the existence of an intriguing crackling noise in the acoustic emission and of self-affine fractals in the crack surface morphology. Recent advances ...

Statistical models of fracture

Low velocity impact response of fibre-metal laminates – A review

2D braided composites: A review for stiffness critical applications

The extensive use of FRP composite materials in a wide range of industries, and their inherent variability, has prompted many researchers to assess their performance from a probabilistic perspective. This paper attempts to quantify the uncertainty in FRP composites and to summarise the different stochastic modelling approaches suggested in the literature. Researchers have considered uncertainties starting at a constituent (fibre/matrix) level, at the ply level or at a coupon or component level. The constituent based approach could be further classified as a random variable based stochastic computational mechanics approach (whose usage is comparatively limited due to complex test data requirements and possible uncertainty propagation errors) and the more widely used morphology based random composite modelling which has been recommended for exploring local damage and failure characteristics. The ply level analysis using either stiffness/strength or fracture mechanics based models is suggested when the ply characteristics influence the composite properties significantly, or as a way to check the propagation of uncertainties across length scales. On the other hand, a coupon or component level based uncertainty modelling is suggested when global response characteristics govern the design objectives. Though relatively unexplored, appropriate cross-fertilisation between these approaches in a multi-scale modelling framework seems to be a promising avenue for stochastic analysis of composite structures. It is hoped that this review paper could facilitate and strengthen this process.

Quantification of uncertainty modelling in stochastic analysis of FRP composites

weave, architecture, yarn crimp, and the various mechanisms of energy absorption of the fabric, discussed later. To briefly compare various commercial brands of fabrics, Zylon woven fabrics absorb nearly twice the energy per unit areal density specific energy absorbed SEA than both Kevlar and Spectra, when gripped on all four edges, and almost 12 times that of aluminum fuselage skin. The ballistic impact performance of PBO systems is substantially superior to Kevlar 29 systems and marginally better than Kevlar KM2 systems 4. It is reported in Ref. 5 that Spectra fibers are ten times stronger than steel. Previous review work includes a database of early ballistic fabric research by Cunniff 6, and the mechanisms influencing ballistic performance of woven fabrics by Cheeseman and Bogetti 7.

Ballistic Impact of Dry Woven Fabric Composites: A Review

Woven fabric composite material model with material nonlinearity for nonlinear finite element simulation

This work presents a computational material model of flexible woven fabric for finite element impact analysis and simulation. The model is implemented in the non-linear dynamic explicit finite 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 flexible 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 defined material subroutine. The developed model and its implementation is validated using an experimental ballistic test on Kevlar woven fabric. The presented validation shows good agreement between the simulation utilizing the present material model and the experiment. Copyright © 2001 John Wiley & Sons, Ltd.

Computational micro-mechanical model of flexible woven fabric for finite element impact simulation

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.

Ala Tabiei

Papers

Ballistic Impact of Dry Woven Fabric Composites: A Review

Woven fabric composite material model with material nonlinearity for nonlinear finite element simulation

Computational micro-mechanical model of flexible woven fabric for finite element impact simulation

Computationally Efficient Micromechanical Models for Woven Fabric Composite Elastic Moduli

Comparative study of predictive methods for woven fabric composite elastic properties