Re-Evaluation of Fatigue Evaluation Procedures for Weld Root Failure 2019-01-0529
The FE modeling guidelines and the design master S-N curve for weld root failure was recently proposed using the mesh-insensitive structural stress method. Due to increasing demands to validate the design master S-N curve, various weld root fatigue failure cases were reanalyzed based on well-documented weld root fatigue failure studies including different weld shapes and sizes, plate thickness combinations, and loading modes. Also, the validations of the master S-N curve for weld root failure were conducted using a well-documented structural joint fatigue data set as well as additional fatigue test results.
Through the analyses, the proposed weld root failure modeling guidelines and the structural stress-based master S-N curve approach were confirmed to be good to use for practical applications to predict weld root failure.
The critical weld size using the ratio of weld size and plate thickness for load carrying cruciform joints under tensile loading was re-evaluated. The structural stress method based critical crack size demonstrated the predictability of the failure mode (i.e., either toe failure or root failure) based on the relationship between weld size and plate thickness.
It was observed that the level of residual stresses at the weld root region are drastically affected by the gap distance or the penetration depth. Therefore, the combined effects of the levels of residual stresses and applied loading affect the fatigue behavior.
