الفهرس | Only 14 pages are availabe for public view |
Abstract In the application of composite materials where the state of stress may not be predictable or where it is known that the stresses are approximately equal in all directions, unidirectional composites may not be suitable. such applications require composites that have approximately equal strengths in all directions. Multilayered composites can be constructed from layers of unidirectional laminates having different fiber orientations so that the resulting composite is . essentially isotropic in a plane. Such composites have the disadvantage that, although the overall composite is equally strong in all directions, the surface layers, where the failure is quite often initiated, are still very weak in the transverse direction. In applications where protection from a corrosive environment is an important factor, such as in storage tanks in chemical industries, and in many applications in the automobile industries, composites of unidirectional laminates do not solve the problem completely. Thus, it is advantageous to have each layer or lamina isotropic in some applications. An effective way of producing an isotropic layer is to use randomly oriented fibers as the reinforcement. In the present work we studied the mechanical ·behaviour and the manufacturing quality parameters for in-plane random glass fiber/polyester composite plates produced by a hand lay-up technique for a wide range of fiber weight ratio (Wf*= 15-55%). A statistical analysis based on 2 and 3-parameter weibull functions were used to predict a new empirical relations between the fiber volume ratio V f and the other manufacturing quality parameters fiber weight ratio Wf, void content V, density p & moisture content H, also a new relations between c |