Improvement of Cyclic Void Growth Model for Ultra-Low Cycle Fatigue Prediction of Steel Bridge Piers

Abstract

The cyclic void growth model (CVGM) is a micro-mechanical fracture model that has been used to assess ultra-low cycle fatigue (ULCF) of steel structures in recent years. However, owing to the stress triaxiality range and contingency of experimental results, low goodness of fit is sometimes obtained when calibrating the model damage degradation parameter, resulting in poor prediction. In order to improve the prediction accuracy of the CVGM model, a model parameter calibration method is proposed. In the research presented in this paper, tests were conducted on circular notched specimens that provided different magnitudes of stress triaxiality. The comparative analysis was carried out between experimental results and predicted results. The results indicate that the number of cycles and the equivalent plastic strain to ULCF fracture initiation by the CVGM model calibrated by the proposed method agree well with the experimental results. The proposed parameter calibration method greatly improves prediction accuracy compared to the previous method.

Effect of Corroded Surface Morphology on Ultra-Low Cycle Fatigue of Steel Bridge Piers

“…In Equations (4)–(6), T is the stress triaxiality, is the cumulative equivalent plastic strain at the beginning of each tension cycle, and are the increment of equivalent plastic strain at each tension and compression cycle, respectively, λ is the damage degradation parameter of materials, and η is the fracture parameter under monotone loading. This paper adopts the CVGM fracture criterion calibrated by Li [ 34 ] to calculate the ULCF crack-initiation life of corroded steel piers at the corner of the weld toe. The criterion divides different applications of the damage degradation parameter by the average stress triaxiality.…”

Experimental and Numerical Study of Combined High and Low Cycle Fatigue Performance of Low Alloy Steel and Engineering Application

“…In order to facilitate the application of the proposed CVGM in engineering practice, Liao et al [ 27 , 28 ] and Yin et al [ 29 ] calibrated the parameters in the micro-mechanism model for the commonly used structural steels by experiments. Li et al [ 30 ] found that the level of the stress triaxiality has a significant impact on the damage degradation parameter, and a modified calibration method was proposed in their study. These research findings and proposed methods can be used to evaluate the fatigue failure caused by LCF loadings without considering the HCF pre-damages, namely these studies focused on the LCF properties of the damage free materials.…”

Prediction of Ultralow Cycle Fatigue Damage of Thin-Walled Steel Bridge Piers

“…To facilitate the application of the micromechanical model, Liao et al [19][20] and Yin et al [21] calibrated the parameters in the CVGM by material tests and scanning electron microscope tests. Li et al [22] proposed a new CVGM parameter calibration method to extend the scope of its application to a relatively lower-stress triaxiality condition. Moreover, the effect of the damage degradation parameter on the prediction of ULCF failure in steel bridge piers was discussed by them.…”