Interlaminar Fracture Toughness Characterization of Laminated Composites: A Review

• Published in: Polymer reviews Vol. 60; no. 3; pp. 542 - 593
• Main Authors: Shrivastava, Ruchir, Singh, K. K.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 02.07.2020; Taylor & Francis Ltd
• Subjects: Bonding strength; Carbon fibers; Carbon nanotubes; CNT; Delamination; Energy absorption; Fiber composites; Fiber volume fraction; Fracture toughness; Functionalization; Interleaving; Laminar composites; Laminates; Loading rate; mode-I and mode-II interlaminar fracture toughness; Parameter modification; Specimen geometry; Stacking sequence (composite materials); Surface roughness; Weight
• ISSN: 1558-3724; 1558-3716
• DOI: 10.1080/15583724.2019.1677708

Interlaminar fracture toughness had been the subject of great interest for several years and is still interesting to the research community. In this article, a comprehensive analysis of fracture toughness in FRP laminates is presented. Primarily, toughness studies are undertaken on glass and carbon fiber reinforced composites under mode-I and mode-II loading conditions. The fracture behavior and its failure pattern depend on a number of parameters: fiber sizing/coating, matrix modification, insert film, fiber volume fraction, stacking sequence, specimen geometry, loading rate and temperature change. In fact, a state-of-the-art process enables increasing fracture resistance with "matrix toughening by carbon nanotubes (CNT) inclusion". It enables production of materials having ultra-high strength and low weight. The present study has highlighted the available techniques of CNT incorporation: mechanical mixing, grafting and interleaving. Other aspects, such as the dispersion level, matrix viscosity, fiber surface roughness, loading weight %, bonding strength with epoxy, height and density of grown CNT, energy absorption mechanism during delamination, etc., have been examined as well. Although a clear correlation of all these parameters with fracture toughness is hard to establish, there is growing understanding of the surface-grown CNTs and interleaving processes as they ensure significant increase in fracture toughness.