PREDICTION OF COMPRESSION STRENGTH OF UNIDIRECTIONAL POLYMER MATRIX COMPOSITES

An analytical formulation is developed for the prediction of compressi on strength of unidirectional polymer matrix composites. The exact sol ution of the problem is simplified into an explicit equation for compr ession strength. Then, a nondimensional group is identified and used t o propose a simple formula for the prediction of compression strength. The final formula can be used in design or to estimate the compressio n strength of production parts without performing compression testing. No empirical or semi-empirical parameters are used. The formula is va lidated for a broad class of materials including a variety of polymer matrices reinforced with carbon and glass fibers. Three parameters are required: the shear stiffness and strength of the composite and the s tandard deviation of fiber misalignment in the composite. All three pa rameters can be measured by well-established techniques. Data from the literature is used to validate the formula.