Experimental and numerical assessment of self-pierce riveting of HIF steel and AA5083 sheets with fracture prediction

The current work aims to understand the impact of rivet hardness, diameter and length, and bottom sheet thickness on the quality of Self-piercing rivet (SPR) joints using pip and flat dies. High-strength interstitial free (HIF) steel and AA5083 sheets are joined, with AA as the bottom sheet. Upper sheet fracture during SPR is predicted by a novel strain mapping method through the Shear Fracture Forming Limit Curve (SFFLC) and the existing Hosford-Coulomb fracture model (HC model) using Abaqus, along with experimental validation. Successful SPR joints between the sheets are possible only with a pip die. Rivet cracks and local rivet bending are observed for the flat die. Rivet hardness, rivet length, and bottom sheet thickness show synergistic effects on riveting force, shear fracture, and joint indices. As a result, using smaller rivets (3.35 mm diameter) along with a flat die is not recommended for the sheets, and the 5.3 x 6.0/pip/2/480 configuration is the best choice for joining HIF steel and AA5083. In the numerical prediction, riveting force and indices are predicted with acceptable error within experimental variations and accuracy levels available in the literature. Moreover, SFFLC and HC model-based fracture predictions are accurate; however, SFFLC is easy to implement with calibrated lab scale test data.