Fatigue analysis of square-to-square tubular T-joint with surface crack

摘要

Experimental fatigue studies are conducted on a steel square-to-square tubular T-joint subjected to combined load, i.e. combination of axial loading (AX), in-plane bending (IPB) and out-of-plane bending (OPB). The Alternating Current Potential Drop (ACPD) technique is used to monitor the joint crack growth and crack shape development along the chord weld toe around the corner of the T-joint. Test results revealed that the crack also curved under the chord weld toe. A geometrical model that can simulate the curved crack surface defined as a polynomial function is generated for numerical analyses. The results are compared against those obtained from experiments using the Paris law. Good agreement between the results confirmed that the proposed mesh generation and modelling procedure is reliable and suitable for fracture mechanics analysis. As a simplification, a straight line with a 45°angle with the chord surface can be used to represent the actual crack surface under the weld toe for the T-joint subjected to combined load.