Unlike simple "rule of thumb" bolt sizing charts, VDI 2230 considers the complex interaction of elastic deformations between the bolt and the clamped parts. It assumes that a bolted joint acts like a system of springs. When you tighten a bolt, the bolt stretches (acting as a tension spring) and the clamped components compress (acting as a compression spring).
The , developed by the Association of German Engineers (Verein Deutscher Ingenieure), is the global gold standard for the systematic calculation of high-strength bolted joints. The latest full revision, VDI 2230 Part 1 (2021) , refines these calculation models to account for modern manufacturing tolerances, updated material sciences, and advanced tightening techniques. vdi 2230 2021