Abstract:
Carbon nanotube (CNT) is a multifunctional nanostructured material with exceptional mechanical, thermal and electrical properties and one of the strongest materials known to men. CNTs are frequently used as reinforcements in composites. However, process induced defects like vacancies and curvature in CNT are common. Such defects are known to have detrimental effects on the overall properties of the composites. In an approach to quantify the effects of CNT waviness on mechanical properties of CNTs and their composites, a multiscale analysis is performed. At the nanoscale analysis, an atomistic model of wavy single walled CNT (Arm chair and Zigzag) is developed and the effect of waviness ratio and wavelength ratio on Elastic modulus is studied. Then a finite element model is developed where fibers are oriented in two different process-induced patterns, aligned and cross orientation. Furthermore, to study the effect of presence of interface material, a layer of polymer with modulus of elasticity of 15GPa is used between the fiber and the matrix. In each case, elastic modulus and shear modulus are determined in both longitudinal and transverse directions and the variation of their values with the change of waviness ratio as well as volume fraction are studied by finite element method where the dilute strain concentration tensor is obtained directly from a finite element solution. Finally these results of mechanical properties are compared with the data found by the modified rule of mixture.
