Enhanced composite laminate fastening and delamination repair using hierarchical thermoplastic composite rivets

Aircraft require numerous composite parts, which are fastened with rivets. However, these rivet fastening processes have several disadvantages, including delamination during drilling, increased weight, galvanic corrosion with metallic rivets, and thermal expansion mismatch. Here, the authors develop a hierarchical carbon fiber reinforced thermoplastic (CFRTP) rivets using MWCNT for high strength and enhanced electrical/thermal conductivity, achieving 907 S/m and 0.750 W/m∙K, respectively. The conductive network of MWCNT and carbon fiber enabled the induction heating-assisted fastening process. The optimal hierarchical structure and fastening process condition were investigated using a development framework with numerical modeling and experiments. The fastened CFRTP rivets showed a maximum of 35 % higher bearing strength than conventional aluminum rivets, with a 43% weight reduction.