Manufacturing and performance studies of laminated composites with nano-reinforced inter-ply interfaces
Date of Issue2014
School of Mechanical and Aerospace Engineering
Laminated carbon fiber reinforced polymer (CFRP) composites offer poor resistance to inter-laminar fracture under loading. This thesis looked into ways for enhancing this resistance and understanding the underlying mechanisms. Multi-scale CFRP composites were envisioned and produced by adding a small amount of either -COOH or -OH group functionalized or inert carbon nanotubes (CNTs) at inter-ply interfaces of laminate stack-ups before curing them. Inter-laminar fracture toughness (ILFT) of these CFRP composites was experimentally evaluated under the opening and in-plane shear modes. Microstructural studies were conducted on the various specimens using field emission scanning electron microscopy to understand the contributing mechanisms to the fracture toughness. Besides the fiber bridging, many other micro-mechanisms involved were identified and their role as the ILFT enhancers was elucidated. The toughening effect of CNTs was subsequently quantified using cohesive element superposition in finite element analysis. In entirety, this research provided a well-defined manufacturing technique for multi-scale CFRP composites, pragmatic ways for ILFT enhancement using CNTs in various proportions and combinations, proper testing for ILFT evaluation, and the identification and understanding of the underlying ILFT enhancing mechanisms.
DRNTU::Engineering::Materials::Mechanical strength of materials