Prediction of compression strength of unidirectional polymer matrix composites

An analytical formulation is developed for the prediction of compression strength of unidirectional polymer matrix composites. The exact solution of the problem is simplified into an explicit equation for compression strength. Then, a nondimensional group is identified and used to propose a simple formula for the prediction of compression strength. The final formula can be used in design or to estimate the compression strength of production parts without performing compression testing. No empirical or semi-empirical parameters are used. The formula is validated 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 standard deviation of fiber misalignment in the composite. All three parameters can be measured by well-established techniques. Data from the literature is used to validate the formula.