Experimental study on ultimate bearing capacity of pre-cracked ship hull stiffened panel under low-cycle fatigue and accumulative plasticity coupling

Ships navigating in complex sea conditions typically do not experience catastrophic failure due to a single extreme load; rather, the primary structural components such as stiffened panels of the hull undergo plastic deformation under repeated cyclic loading and may develop cracks under low-cycle fatigue. This leads to a decrease in ultimate bearing capacity and eventual structural failure due to insufficient ultimate strength, resulting in hull buckling. Currently, methods for evaluating the ultimate strength of ship hull stiffened panels under cyclic extreme loading considering the coupling effects of accumulative plasticity and low-cycle fatigue are not well-developed. Therefore, there is a need for research into computational methods for assessing the ultimate strength of stiffened panels structures considering the coupling effects of these two factors. This paper investigates the ultimate load-bearing capacity of pre-cracked stiffened panels under the combined effects of accumulative plasticity and low-cycle fatigue. During the experiments, hysteresis curves of stress-strain relationships and relevant fracture parameters for stiffened panels were obtained under various crack positions and load conditions. Ultimately, the study provides the ultimate load-bearing capacity of stiffened panels considering low-cycle fatigue and accumulative plasticity interactions, offering a foundational calculation basis for designing vessels under severe sea conditions.