Sergei P. Yushanov and Alexander E. Bogdanovich

ABSTRACT

A general stochastic theory of elastic properties of composite materials with randomly curved spatial reinforcements is developed. The theory of random functions is utilized to evaluate the probabilistic characteristic of the local waviness of the reinforcement. A probabilistic extension of the orientation-averaging model is developed to evaluate the elastic response of composites with multidirectional reinforcement having stochastic waviness. One fundamental advantage of the developed theory, compared to existing analytical approaches, is that an exact description of the reinforcement waviness is not required for predicting elastic properties. The only essential characteristic used as input data are the mean reinforcements paths and standard deviation of the local tangent, which is a random value characterizing the reinforcement path deflection from the “perfect” one.

It is shown that the existing approaches for evaluating elastic properties of the composite with imperfect continuous fiber reinforcements can be obtained from the developed theory as particular cases. The theory is illustrated with examples of a unidirectional composite and a helically wound composite with randomly curved reinforcements. Numerical examples show that the even small local waviness of the reinforcements paths may significantly affect the elastic response of the composites considered.