Volume Effects and Probabilistic Properties of Chopped Fiber Reinforced Composite Materials

Abstract

The elastic properties of thermoplastic composites reinforced with randomly oriented chopped strands are measured and statistically evaluated. Chopped fiber composites exhibit a probabilistic nature due to the randomness in their fiber orientations, and packing arrangement; hence, a probabilistic estimation is essential to provide an accurate representation of their performance. An analytical approach is then proposed, and explicit expressions for the probabilistic values of the elastic properties are approximately given in terms of basic data such as dimensions of the gage area, and dimensions and elastic properties of the randomly oriented strands. The estimated elastic properties of the composites agree well with the experimental results. Present formulae that can suitably express the effects of the sizes of the gage areas on the mean values and standard deviations of the tested results help to determine some rules on the testing standards and the method of data acquisition.