The effect of inclusion waviness and waviness distribution on elastic properties of fiber-reinforced composites

In this study we investigated the effects of inclusion waviness and its distribution to the effective composite stiffness. Different waviness conditions were analyzed: uniform waviness with variable inclusion orientation or aspect ratio, and uniform aspect ratio with variable waviness. The inclusion waviness was found to have a greater effect on tensile moduli and shear modulus for unidirectional composites; however, if the inclusions are either randomly dispersed or partially aligned, the degree of waviness effect was smaller. The elastic moduli were also over-estimated if inclusion aspect ratio or waviness followed symmetric distributions. In addition, the waviness distribution effect was larger when larger inclusion waviness was introduced in a composite. The lack of fiber waviness distribution assumption was found to lead to inaccurate composite stiffness predictions, especially for composite with higher fiber volume fraction. We also demonstrated the inclusion waviness effects on the tensile modulus of carbon nanotube-reinforced composites. The results showed that the disparity between theoretical predictions and experimental data could be due to different inclusion waviness conditions. (C) 2010 Elsevier Ltd. All rights reserved.