Simulation Analysis of Elasto-Plastic Deformation of TC16 Mechanical Locking Nuts During Installation

The installation process of the mechanical locking nuts was simulated by using Abaqus. Supported by forming tests and metallographic analysis, this study investigated the elasto-plastic deformation of the nut during installation and determined the influence of the structural parameters of the nut lobe on the forming quality of the locking structure. The results reveal that during nut deformation, plastic deformation predominates near the head region, while localized structural displacement occurs toward the tail end. For MJ8×1 specification nuts, the axial displacement of the lobe material increases from 0.06 mm to 0.21 mm from the plastic deformation zone to the localized structural displacement zone. In contrast, the tangential displacement decreases from 0.35 mm to 0.07 mm. Within the range of 0.16 mm to 0.20 mm, the radial displacement initially decreases before increasing. The radial displacement at the thread flank exceeds that within the thread by 0.09 mm. Material in the indirect loaded zone of the nut primarily exhibits a radial displacement of 0.25 mm. A smaller lobe radius r and a longer chord length d correspond to a higher thread side elongation rate e , whereas the axial length l of the lobe shows no significant influence on e. When the parameters fall within the ranges of 1.20 mm <  r  < 1.35 mm, 2.30 mm <  d  < 2.40 mm, and 2.50 mm <  l  < 2.70 mm, e exceeds 3.0%, indicating favorable forming quality of the locking structure.