Mechanical and Architectural Characteristics of Plain-Weave Fabric under Bi-axial and Pure Shear Loading
AuthorBasit, Munshi M.
AdvisorLuo, Shen Y.
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Soft matrices reinforced by textile preforms are considered as flexible composites that can undergo large elastic deformation. The mechanical behaviors of these composites are highly nonlinear, involving both material and geometric nonlinearities. To conduct a finite element analysis studying woven fabric structures, one of the desired approaches is to develop an equivalent continuum model representing the mechanical behavior of the fabric's unit-cell. During large deformation, significant fabric architecture rearrangement occurs. To include this geometrical nonlinearity into a continuum model, it is always a challenge.Plain weave fabrics are widely used as reinforcements in textile composites. The objective of this thesis is to study the large nonlinear elastic deformations of plain weave fabrics under multi-axial loading. Two theoretical models are presented in this thesis. A sinusoidal unit-cell model has been used to describe the in-plane bi-axial mechanical behavior of plain weave fabrics. A working MathCAD program is attached, where only real physical properties about the fabric (i.e., crimps, numbers of yarns per unit length, and yarn properties) are required as inputs. The predictions from the current model agree with the experimental data for a fabric under biaxial loading ratios of 0:1, 1:1, 1:2, 1:5 and 5:1. They also agree well with FEA simulations of the mechanical behaviors of the unit cell. An analytical model, based on the Bernoulli-Euler Beam theory and Coulomb's friction model, is proposed for the pure shear loading case. In developing the constitutive models, to understand the detailed deformation of the fabric unit-cell, non-linear finite element analysis has been extensively used in this work. Two truss models for the unit-cell have been developed in this work. The straight yarn model simulates the fabric forming process and predicts the mechanical behavior of the fresh fabric. In the sinusoidal model studies, the mechanical behavior of the fabric is based on the assumption that no residual stress exists in the fabric prefoms.