Experimental studies on crack propagation and accumulative mean strain of cracked stiffened plates under low-cycle fatigue loads

In this work, the effects of low-cycle fatigue loading and stiffener height on crack propagation regularities of stiffened plates are investigated. The tests are conducted on 14 cracked stiffened plate specimens using an MTS322 fatigue tester. Videos showing the crack propagation are recorded using two electron microscopes, and the data form which are used to plot the a-N curves. The accumulative mean strain curves are obtained from the displacement data of the loading rod. The a-N curves show that during the entire low-cycle fatigue loading, the stiffener constrains the crack propagation, causing the crack propagation length of the stiffener to be greater than that of the plate. Additionally, the accumulative mean strain, which has a maximum value of about 1.62%, is observed in the specimen and is unrecoverable. The data presented in this work may be useful for a more accurate calculation of time-dependent change of the ultimate strength of specimens under low-cycle fatigue loads.