Effects of fiber orientation in a soft unidirectional fiber-reinforced material under simple shear deformation

Abstract

The influence of the fiber orientation on the mechanical behavior of a soft unidirectional fiber-reinforced composite under simple shear is investigated. Specimens made of an elastomeric matrix containing one family of parallel and continuous fibers were fabricated. Simple shear tests were performed on composite specimens with different angles of orientation of the fibers. A modified standard reinforcing model, which is based on two pseudo-invariants, was used to predict the shear response of the flexible composite specimens. Moreover, an alternative model was also proposed. Mechanical properties of the neat matrix and fibers were used as input data and the elastic properties of the composite were evaluated using the rule of mixture. A reinforcement parameter was taken into account for correcting the values of the elastic properties of the composite. The agreement between experimental data and both predictive models is remarkably good. Results showed that the shear contribution of the soft composite is dominant for small deformations, while for large deformations the stretching resistance of the fibers is more pronounced. The initial shear modulus of the soft composite with θ = 90° is slightly larger than one for θ = 0°. However, this property increases significantly for fibers oriented at angles different from 0° and 90°. The maximum initial shear modulus is found for specimens with angles of orientation between 40° and 60°.