A new method for cyclic crack-tip plastic zone size determination under cyclic tensile load

•We propose a new method to predict the crack-tip plastic zone size (Ryc) for center cracked plates under cyclic tensile load.•The maximum crack opening displacement (Δu) and variable quantity of maximum crack opening displacement (Δδ) are introduced.•The explicit expression of Ryc related to Δu and Δδ is acquired by least square method.•The expression considers some factor effects, such as crack geometry, applied load, yield stress, and loading sequence.•The method is suitable for center cracked finite plates with different material under cyclic tensile loads.

This paper presents a new method to determine the cyclic crack-tip plastic zone size (CTPZS) in the center cracked plate subject to cyclic tensile load. The maximum crack opening displacement (MCOD) and the variable quantity of MCOD (VMCOD) are used to estimate cyclic CTPZS in this method. Based on the series of calculation results by finite element analysis, an explicit expression of cyclic CTPZS versus MCOD and VMCOD is fitted by the least square method. The expression enables to eliminate the influences of crack geometry, plate sizes, elastic modulus, yield stress, plane state, stress ratio, overload ratio and load sequence. Therefore, the presented method is suitable for center cracked finite plate models with different material under cyclic tensile load.