Short fibers fiber orientation

M. Vincent, J.F. Agassant. Experimental study and calculations of short glass fiber orientation in a center gated molded disc. Polym. Compos., 1 (2), 76-83,... 

A discontinuous fiber composite is one that contains a relatively short length of fibers dispersed within the matrix. When an external load is applied to the composite, the fibers are loaded as a result of stress transfer from the matrix to the fiber across the fiber-matrix interface. The degree of reinforcement that may be attained is a function of fiber fraction (V/), the fiber orientation distribution, the fiber length distribution, and efficiency of... 

The Bowyer and Bader [96] methodology can be used to predict stress-strain response of short fiber-rein-forced plastics. The stress on the composite (cT( ) at a given strain can be computed by fitting the response to a form of Eq. (4) with two parameters, the fiber orientation factor (Cfl) and interfacial shear strength (t,). 

First-generation polymer composites (e.g., fiberglass) used thermosetting epoxy polymers reinforced with randomly oriented short glass fibers. The filled epoxy resin could be cured into a permanent shape in a mold to give lightweight, moderately strong shapes. 

Fu, S. and Lauke, B Effects of fiber length and fiber orientation distributions on the tensile strength of short-fiber-reinforced polymers, Composites Sci. Technol., 56, 1179 (1996). 

Fakirov, S. and Fakirova, C., Direct determination of the orientation of short glass fibers in an injection-molded polyethylene terephthalate) system, Polym. Composites, 6, 41 (1985). 

Toughness theories for short and randomly oriented fiber composites... 

Kardos J.L. (1981). Strength of oriented short fiber reinforced plastics. In Proc. 36th Annual Tech Conf. Reinforced Plast. Compo.sites, SPI. Paper 2E. 

Real situations demand more uniformity in composite properties than can be provided by unidirectional composites. Therefore lamina stacking sequences are made where the fiber orientation is altered to provide good properties in all directions. Lamina composed of fiber and matrix in which the fibers are all parallel to each other are stacked on top of each other with a systematic variation in fiber direction. These lamina are then bonded together and the resulting material has more uniformity in properties. Likewise in short fiber or discontinuous fiber composites fiber orientation is random. Therefore properties in directions other than parallel to the fiber (i.e. off-axis) are important70>. 

Write a short explicit finite difference program to compute the fiber orientation function in a compression molding process with stretching only in the x-direction. Test the program with an example, where a 3 mm thick 50 x 50 cm plate is compression molded with an initial mold coverage of 50%. Assume an interaction coefficient C/ = 0.05. Assume initial fiber orientation distribution that is random. 

Fig. 11.24 The effects of the fiber aspect ratio, at constant 30% wt loading, on glass-filled polyamide-6. [Reprinted by permission from H. M. Latin, Orientation Effects and Rheology of Short Glass Fiber-reinforced Thermoplastics, Colloid Polym. Sci., 267, 257 (1984).]...

H. M. Laun, Orientation Effects and Rheology of Short Glass Fiber-reinforced Thermoplastics, Colloid Polym. Sci., 262, 257-269 (1984). 

Flow within molds in processes such as IM and resin transfer molding (RTM), or through dies in the extrusion process, can orient the molecules of the resin as well as short or long fibers. This orientation can result in the designed properties desired or, if not properly processed, can result in inferior properties which may become evident in the form of reduced resistance to crazing, low impact strength, lowered creep rupture strength, etc. 

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