Analysis and optimization of rivet load distribution in multi-rivet connections of thermoplastic composite rivets

GF/PP thermoplastic composite components predominantly employ metallic fasteners, leading to corrosion and weight issues. This study utilized an extrusion process to fabricate GF/PP thermoplastic composite rivets with properties akin to laminated panel materials. Through the controlled application of heat and pressure to the rivet ends, a novel connection structure was established. The article fabricated thermoplastic composite joints with varying end configurations and compared them with metallic rivet joints. Emphasizing the convex form, diverse multi-rivet links were crafted for single-lap tensile samples. Integrating tensile tests and strain gauge measurements, this research explored load distribution patterns across diverse rivet quantities and assessed the impact of size on distribution. Furthermore, finite element software was used to dissect the load distribution patterns and failure mechanisms in the multi-riveted connection structure. Drawing from experimental findings, convex GF/PP rivets exhibited an 18% higher tensile load than metallic ones, with a simultaneous 32% weight reduction. In multi-rivet connections, end rivets demonstrated higher load-bearing capacity. Enhanced spacing and plate width improved load distribution, elevating joint load capacity by 7% (spacing 25 mm to 55 mm) and 6% (width 30 mm to 55 mm). The simulation results indicate that increasing the spacing reduces the stress concentration at the first nail location.