Fatigue strength assessment of welded steel fasteners using structural stress concept with consideration of the mounting pre-load

The document presents a comprehensive investigation into the fatigue strength assessment of welded fasteners, specifically bolts and nuts, used in various engineering applications. A fatigue strength assessment approach using a structural stress concept is established, accounting for the influence of mounting pre-loads and residual stresses from the welding process. With the developed approach, the fatigue strength of all investigated variants can be assessed with a scatter of 1:2. The experimental investigations showed that an early decrease in pre-load forces negatively affects the fatigue strength. While pre-load forces can enhance fatigue strength, a reduction in pre-load during service loading must be avoided to ensure a safe life.