Study of vibration frequency-fatigue strength action of 6061-T6 aluminum alloy during fillet welding

The research mainly focuses on the fatigue strength characteristics of 6061-T6 aluminum alloy fillet welds under different vibration frequencies. Firstly, by introducing Stress Life Curve (S-N Curve) and Probability Stress Life Curve (P-S-N Curve), the external vibration stress effects of the main load-bearing points in the stress environment of welded joints are analyzed. Subsequently, a vibration test control system is designed to analyze the relationship between vibration frequency and fatigue strength through nominal stress analysis and hot spot stress analysis. The research findings revealed that under the nominal stress analysis method, the P-S-N fitting curve showed a declining trend with an increase in fatigue life for stress variation curves with survival rates of 50 %, 95 %, and 97.7 % at vibration frequencies of 57.5 Hz, 67.5 Hz, and 77.5 Hz. At the same survival rate stress conditions, the fatigue life variation formed by resonance frequency was smaller, and the fatigue life in the resonance state was relatively lower. There is a certain correlation between vibration frequency and fatigue strength, with resonance frequency corresponding to relatively low fatigue life. This research result helps to reveal the fatigue behavior of 6061-T6 aluminum alloy fillet welds under different vibration stresses, providing a reference for the structural safety design of aluminum alloy components.