الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Fibers differ from metals in one major way and that is fibers cannot undergo compression as they tend to buckle under compressive stresses, thus giving the rather desirable aesthetic property of flexibility and drape, which is absolutely unacceptable in metals.Fiber fatigue is a relatively new concept compared to metal fatigue where unforeseen disastrous accidents in the early days of engineering led to serious consideration of metal fatigue. The fatigue failure is important for many end-use applications such as apparel, furnishings, automobile upholstery and industrial fabrics such as conveyor belts.Many researchers studied the effect of fatigue on fabrics and yarns and found that, it is difficult, first, to separate the effects of fatigue on the fibers themselves from effects(such as inter fiber abrasion) that reside in the yarn or cord structure and, second, to define the nature of the complex fatiguing strains in the fibers.Bagging is a result of repeated cyclic load on the fabric. The bagging deformation is composed of biaxial tensile and shearing deformation. During this process, the yams are subjected to a combination of tension, shearing, bending, and compression forces.Therefore, the complex rheological behavior of the fabric during bagging deformation is determined by the sophisticated interactions between elastic and viscoelastic behavior of fibers and yarn-fabric structures.Composite reinforced by woven fabric is known to have high specific stiffness and, in combination with automatic manufacturing processes, makes it possible to form complex components (aircraft, boat, automotive, and military) with high level of weight and cost efficiency due to their excellent mechanical properties. One of the most attractive properties of the fabric reinforcements is that they are easily handled and automatically processed, which can lower the production cost. During the process of forming of textile composites, wrinkling is one of the most common flaws, often leading to unexpected failures.In this work, the effect of cyclic load on highly oriented fibers in loose assembly with low twist, yarns with different spinning systems and different twist factors and the effect of fatigue on knitted fabrics with different yarn types are studied. This is achieved through developing a method to produce 3D fabric preforms for fabrics using fatigue stimulus and developing a procedure for the design of 3D fabric performs. from the experimental work it was proofed that the application of a cyclic load on the fabric change its mechanical characteristics and fabric bagging can be resulted, so a suggestion was made to use this effect to produce 3-D textile forms with predetermined shapes without wrinkles, with the aid of hot air to help the formation of complicated 3-D fabric shapes without the appreciably change of the fabric mechanical properties.