Effect of CNT waviness and van der Waals interaction on the nonlinear compressive behaviour of epoxy/CNT nanocomposites

A 3D nonlinear computational model was developed to predict the compressive behaviour of epoxy/carbon nanotube (CNT) nanocomposites, taking into account the particle waviness and interactions at the polymer/particle interface. The behaviour of epoxy/CNT interface was modelled using the cohesive zone concept, adapted to capture perfect and weak secondary van der Waals (vdWs) bonding. The computational predictions of Young’s modulus and yield peak stress were found to be in agreement with experimental results obtained for nanocomposite samples with functionalised CNTs. Young’s modulus was predicted to scale linearly with increasing CNT mass fraction, while a nonlinear relation was found for the yield peak stress. CNT waviness affected the average hydrostatic stresses and total Cauchy stresses in the matrix component. Those stresses were reduced for the case of wavy CNTs, and increased for the case of straight CNTs, when compared to the pure epoxy.