Fatigue strength in terms of stresses measured by gauges attached with its ends to be at weld toes

Abstract

To evaluate stresses including stress concentration at weld toes for fatigue evaluation of complex shape welded structures such as railway bogie frames, previous studies proposed the stress assessment procedure through measuring strains of actual structures by attaching strain gauges with its edges to be at weld toes. This paper evaluates design fatigue strength in terms of the measured stress from published fatigue data and re-analysis of those fatigue tests. Results showed that fatigue strength at 2×10⁶ cycles with 0.13% failure probability and at 1×10⁷ cycles with 2.3% failure probability were similar, and those values were stress range of 88.7–94.4 N/mm² for stress ratio of 0–0.3. The fatigue strength values in terms of the measured stress were approximately the same or slightly higher than those of hot spot stress.