Numerical simulation of damage evolution of bolted connectors considering fretting fatigue effect

In engineering, the failure of bolted connector is mainly caused by multi-axis non-proportional fretting fatigue damage. A three-dimensional finite element model of bolted connector is established in this paper, and a damage constitutive model suitable for multi-axial fatigue analysis is established based on the critical plane SWT (Smith Watson-Topper) method and continuous damage mechanics theory. A material subroutine UMAT is developed to describe the damage model and realizes the visualization of the damage evolution process caused by the fretting fatigue effect. Based on the test, the validity of the program is verified, the fretting fatigue characteristics and damage evolution characteristics of the bolted connector are analyzed. The results show that (i) the damage evolution analysis method can make up for the deficiency that the critical plane SWT method is only used for simple components and can be applied to the damage evolution analysis and fatigue life evaluation of three-dimensional complex structures. (ii) The crack initiation position of the connecting plate does not change with the magnitude of the tensile load and pre tightening force. In the process of losing the bolt preload from 1 to 0.8 times, the connected parts will be damaged faster as the preload 20 decreases.