The welding residual stress re-distribution behavior during fatigue crack propagation in butt-welded high-strength steel plates for ship construction is investigated based on experimental test results and numerical analyses. The specimens’ initial welding residual stresses are obtained from X-ray for middle tensile (MT) specimens cut from butt-welded high-strength steel plates. Then, fatigue crack propagation experiments on MT specimens are conducted, and a strain gauge is used to measure the residual stress re-distribution field around cracks. A practical fatigue crack propagation simulation procedure is developed with a dynamic update of in-situ welding residual stress, where the residual stress intensity factor K_res of the MT specimen is deduced. The stress ratio effect on K_res during fatigue crack propagation is analyzed and a good agreement between experimental and numerical results is achieved.

Keywords: Fatigue crack propagation; Welding residual stress; Plastic re-distribution; Stress ratio effect