Micromechanical Investigation of Crack Bridging in CNT Based Nanocomposites

Abstract

Carbon nanotube (CNT)-reinforced polymer nanocomposites have emerged as highperformance materials for aerospace, automotive, and electronic applications due to their exceptional mechanical, thermal, and electrical properties. One of the primary mechanisms enhancing fracture toughness in CNT-based nanocomposites is crack bridging, in which CNTs span microcracks and transfer stress, thereby delaying crack propagation and increasing energy dissipation. Understanding crack bridging at the micromechanical level is essential for optimizing composite design and predicting fracture performance. This study presents a comprehensive micromechanical investigation of crack bridging mechanisms in CNT-based polymer nanocomposites. Experimental observations, finite element modeling, and analytical micromechanics are integrated to explore the influence of CNT morphology, dispersion, orientation, and interfacial adhesion on crack bridging efficiency. The results demonstrate that well-dispersed, high-aspect-ratio CNTs significantly enhance fracture toughness by extending the fracture process zone, promoting fiber pull-out, and facilitating interfacial debonding, with implications for the design of damage-tolerant nanocomposites.