Effect of CNT waviness on the elastic modulus of carbon nanotube reinforced polymer composites

Carbon nanotubes (CNTs) are the filler materials of nanoscale dimensions, which when added to the polymer matrix, form a strong yet light-weight multifunctional composite materials. Before using them effectively and confidently in the aerospace industry, it is important to completely determine their mechanical properties. Previous studies found these properties to be significantly influenced by the waviness of CNTs embedded in the epoxy matrix. In this study, we have developed a unique Python algorithm that is employed to construct the stochastic three-dimensional finite element models, which incorporates the CNT waviness as a variable. Random normal and uniform random distributions are assumed for waviness and orientation angles of the dispersed CNTs, respectively. Four separate finite element models with maximum CNT waviness angles of 0⁰, 25⁰, & 50⁰ are generated for CNT volume fraction of 0.5%. Thereafter, the elastic constants are evaluated and compared for each case. A significant decrease in the properties is observed as the maximum allowable waviness angle of the embedded CNTs in the epoxy is increased. These results suggest that CNT waviness plays a key role in deciding the elastic properties of the CNT based composites.