Study on the Damage Evolution and Suppression of a CFRP Wedge-Structure Countersunk Rivet

During the hammer riveting of aircraft composite wing trailing edges, issues such as unclear damage mechanisms resulting from the continuous impact loading of composite materials, difficulty ensuring connection strength, and issues with damage control remain unresolved. This study investigates the dynamic impact load transfer mechanism during hammer riveting, establishes a model which maps the correlation between impact loads and rivet plastic flow, and develops a composite material VUMAT subroutine (a user-defined material subroutine in Abaqus/Explicit) based on the 3D Hashin failure criterion. A progressive damage simulation model for composite materials subjected to multiple hammer riveting operations is constructed. Based on mechanical analysis, a double-sided countersunk rivet with a support structure is proposed to suppress damage during composite hammer riveting. Simulation and experimental analysis demonstrate that, compared to conventional rivets, the new rivet effectively reduces contact stress (by up to 32.29%). Damage zones are concentrated at the straight hole and at the junction between the straight and countersunk holes. Furthermore, damage modes are simplified to matrix compression and tensile stress, with their respective proportions decreasing by 16.7% and 25.9%.