Rong Wenlong, Deng Junlin^*, Liu Yi, Yu Xiaolin, Xi Liuzhu

Beibu Gulf University

Abstract：

This study systematically investigates the crack propagation behavior of hull plates and stiffened plates under low-cycle fatigue conditions. Comprehensive a–N data sets were established by considering key parameters including stress ratio R, phase difference φ, biaxial stress ratio λ, and single peak overload ratio ROL. The results reveal that hull plates exhibit strong load sensitivity: crack propagation is delayed with increasing R but accelerated with increasing φ or λ. Single peak overloads can extend fatigue life by 10–20%, indicating that crack behavior responds significantly to the local mechanical environment. In contrast, stiffened plates demonstrate superior crack resistance due to rib constraints, which produce uniform crack-tip stress fields and limit propagation paths. Under identical loading conditions, stiffened plates exhibit right-shifted a–N curves with lower propagation rates. Their advantages in crack resistance and service life extension are particularly prominent at high ROL, high R, or large φ values.

Key Words：

fatigue life; crack propagation; low cycle fatigue