Lecture 5 Material forms.ppt

Constituent Material Forms Constituent Material Forms * PART I Composite Material System Constituent Material Forms Lecture Contents Fiber Architecture Terminology Continuous and Discontinuous Fibers Fabrics Preforms, Prepregs, and Molding Compounds Constituent Material Forms * Fiber Architecture Regardless of the material, single fibers do not have any application in composite materials fabrication Different assemblages and arrangements of fibers or fiber structures are used instead Reinforcements can be designed and preformed with unique fiber architectures depending on the product requirements and manufacturing process Reinforcement forms include Continuous (long) fiber structures with fiber length more than 6 mm Strands Rovings Fabrics Discontinuous (short) fiber structures with fiber lengths of 0.5 to 6 mm or less Chopped strands and milled fibers Mats and veils Constituent Material Forms * Terminology Filament: smallest unit of a fibrous material. A fiber is made by spinning or drawing into one continuous entity Strand: an untwisted collection of continuous filaments. The basic starting form for production of the other continuous fiber forms. When the strand is a final product, it is commonly called a single-end roving Roving: a number of yarns, strands, or tows collected into a parallel bundle with little or no twist Yarn: an assembly of twisted filaments or strands to form a continuous length. Used in weaving into fabrics Mat: a fibrous material consisting of randomly oriented chopped filaments, or swirled filaments loosely held together with a binder Fabric: arrangement of fibers held together in two dimensions. A fabric may be woven, nonwoven, or stitched Strand Filament Fabric Mat Yarn Roving Constituent Material Forms * How Glass Fibers Forms Are Produced How does Owens Corning, the company that invented glass fiber, produce fiber forms Constituent Material Forms * Continuous Fibers: Unidirectional Reinforcements Fibers in these forms are all