Stiffened plates with cracked damage are often subjected to constant amplitude and/or variable amplitude cyclic loads in sea environment. Under the stress-controlled asymmetric low-cycle fatigue loads, the coupling effect of low-cycle fatigue crack propagation and accumulative plasticity contributes to the increase of accumulative mean strain of cracked structures. Low-cycle fatigue crack growth and the increase of whole strain of cracked structures will change the bearing capacity of cracked structures. In this paper, experimental study on crack propagation and strain accumulation of cracked stiffened plate under low cycle fatigue load has been conducted. AH32 steel is used to make stiffened plate specimen with crack symmetrically located about stiffener. The accumulative strain of the cracked stiffened plate specimens during low-cycle fatigue crack propagation was obtained. From the experiments for cracked stiffened plates under the low-cycle fatigue loading, it is found out that the crack propagates firstly in the weld and then also gradually takes place in the stiffener. The stress ratio of low-cycle fatigue load and stiffener stiffness have been investigated in the experimental study and it is found out that these parameters significantly affect the low-cycle fatigue crack growth life and accumulation strain of the cracked stiffened plate specimens.
Experimental study on the root-deck fatigue crack on orthotropic steel decks
