Abstract
Cyclic void growth model (CVGM) and continuum damage mechanics (CDM) model are suitable for predicting the damage of ultra-low-cycle fatigue (ULCF) theoretically. However, studies on the prediction of ultra-low-cycle fatigue (ULCF) damage is lacking. To determine which method is better, we used the two methods to predict the damage of ULCF. Firstly, uniaxial tensile and large strain cycle tests were performed on the base metal, weld metal and heat-affected zone and the material parameters were calibrated respectively. The uniaxial plastic strain threshold and toughness parameter of weld metal were minimum, and the dispersion was maximum. The finite element models of the base metal and weld specimens were established based on the calibrated parameters, and the ULCF damage was predicted. Compared with the CVGM model, the CDM model can predict the fatigue life and the relationships among the fatigue and fracture lives, the post-fracture path and the number of cycles to initial damage. The parameter calibration is simple. CDM is superior to CVGM in predicting the ULCF damage of steel and its weld joints.
Highlights
The seismic damage of steel piers has led to ultra-low cycle fatigue (ULCF) damage at the weld joints in addition to the residual displacement caused by excessive plastic deformation and local buckling of steel piers [1]
The above-mentioned descriptions indicate that the traditional fracture mechanics method and the Coffin–Manson formula are unsuitable for the damage prediction of ultra-low-cycle fatigue (ULCF)
continuum damage mechanics (CDM) is superior to cyclic void growth model (CVGM) in predicting the ULCF damage of steel and its weld joints
Summary
The seismic damage of steel piers has led to ultra-low cycle fatigue (ULCF) damage at the weld joints in addition to the residual displacement caused by excessive plastic deformation and local buckling of steel piers [1]. Researchers have made a series of studies on the mechanism of low cycle fatigue (LCF) and ULCF damages of steel [5,6]. Several methods can be used to predict fatigue life, such as traditional fracture mechanics, Coffin–Manson formula, micromechanics model and continuum damage mechanics (CDM). The above-mentioned descriptions indicate that the traditional fracture mechanics method and the Coffin–Manson formula are unsuitable for the damage prediction of ULCF. Micromechanical models have been proposed in recent years to accurately predict the ULCF life [22] These models mainly include the cyclic void growth model (CVGM) [23] and the degraded significant plastic strain (DSPS) model [24]. CDM is superior to CVGM in predicting the ULCF damage of steel and its weld joints
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