The Research On Equivalent Of Cracks In Corroded Pits Of Cable Wire

At present,the cables of cable-supported bridges are usually made of high-strength steel wires.Due to some defects in the current cable protection technology,corrosive media will contact the steel wires and form corrosion pits,which seriously affects the safety of the cables.Because the theory of residual fatigue life about three-dimensional cracks is still immature at present,it is equivalent to treat the three-dimensional cracks as plane cracks,and the remaining fatigue life assessment of components is currently a more common treatment method.Therefore,under the current conditions,in order to evaluate the impact of the corrosion pits of the cable wires on the remaining fatigue life of the cables,the problem of crack equivalentization of the pits must primely be solved.In this paper,the finite element method is used to study the distribution characteristics of Mises stress,equivalent plastic strain(PEEQ),and stress intensity factor about different pit morphologies.The reliability of equivalent fatigue cracks in calculating residual fatigue life is evaluated.The specific research work is as follows:(1)Based on the morphological characteristics of the corroded steel wire,ABAQUS is used to analyze the Mises stress and equivalent plastic strain(PEEQ)of the pits with different long semi-axles,short semi-axes and depths under axial tensile load.And ABAQUS is used to explore the areas where critical cracks may occur when the wire breaks.At the same time,the feasibility and rationality of simplifying ellipsoidal pits are explored by comparing the distribution of Mises stress field at the bottom of deformation pit A,deformation pit B,deformation pit C and ellipsoidal pit.(2)Through the method of pre-cracking in the bottom of the pit,the change of the stress intensity factor under the axial tensile load is solved and compared with the different long semi-axles,short semi-axes and depths.And we can learn the characteristics of the change of crack tip stress after the crack occurs in the steel wire.(3)Using the damage parameters,the pit is equivalent to three semi-elliptical plane cracks,and the stress intensity factor is calculated by using the equivalent plane crack.Then the calculated crack tip stress intensity factor is substituted into the Paris formula to calculate the residual fatigue life of the cable wire,and the calculated value is compared with the experimental value to explore the most suitable crack equivalent method and we will give reasonable equivalent crack suggestions.