Progressive Failure Analysis of Plain Weaves Using Damage Mechanics Based Constitutive Laws

Abstract

The behavior of plain woven fabric composites is studied using three-dimensional finite elements which allows detailed modeling of the geometric complexities and spatial material variations within the fabric. Damages in the composite constituents viz. yarn and pure matrix are modeled on a continuum basis and related to their material constitutive behavior. The 3D constitutive laws describing pure matrix and yarn behavior are developed using a damage mechanics based approach with the dissipated energy density as the damage parameter. The strain energy dissipation (SED) concept is employed to describe the damage state and current stiffnesses of the weave constituents. A progressive failure analysis of plain woven fabrics subjected to tension and in-plane shear is carried out considering both geometric and material nonlinearities. The initiation and progression of damage within the fabric is investigated and the significant damage mechanisms outlined.Keywords: Woven composites, finite element analysis, damage mechanics, constitutive laws, failure INTRODUCTIONMicromechanics of textile composites has been the focus of study by many investigators [1][2][3][4][5][6][7][8][9][10][11]. The proper description of the internal weave geometry and spatial variation in material properties within the fabric presents a formidable task in the analysis of such composites. Most of the analytical studies on such composites have focussed on predicting their elastic properties [1][2][3][4][5][6][7]. Studies relating to prediction of their strength and failure modes are relatively few [8][9][10][11].A detailed study of the significant stresses and strains developed within the fabric and possible damage mechanisms can be accomplished by the use of three-dimensional finite elements. Nonlinear material behavior of composites is due to damage accumulation, which causes changes in the stiffnesses of the material. It is well known that macroscopic failure is preceded by an accumulation of different types of microscopic damage and stiffness losses due to the accumulation of such damage, which cause significant load Existing FE modeling tools and preprocessors are not adequate for rapidly creating complex 3-dimensional models needed for the purpose. Therefore, mesh generation programs were developed which would easily interface with a general purpose FEA software, ABAQUS [12]. FE models can be generated for plain weaves and higher-order satin-weaves using a minimal definition of the textile architecture. In the present approach, damages in the composite constituents are modeled on a continuum basis and related to the material constitutive behavior. The 3D constitutive laws describing matrix and yarn behavior are developed using a damage mechanics based approach, with the dissipated energy density as the damage parameter. The strain energy dissipation (SED) concept is employed to describe the damage state and current stiffnesses of the weave constituents. The yarns are treated as transversely isotropic while the pure matrix pockets are assumed ...