Study On The Service Life Prediction Of Mine Hoisting Ropes Based On Fretting Fatigue

In the process of mine shaft lifting,the hoisting rope is subjected to alternating tension fatigue load and bending fatigue load,which results in the fatigue load of the steel wire inside the rope,the contact load and relative slip between adjacent steel wires,which in turn causes the fretting wear,crack initiation,crack propagation and final fracture of steel wire,that is,fretting fatigue,which seriously reduces the bearing strength and service life of the wire rope.The "Coal Mine Safety Regulations" stipulates that when the diameter of a wire rope is reduced or the number of broken wires reaches 10%,the wire rope shall be scrapped.At present,there is no quantitative method for evaluating the service life of hoisting ropes based on fretting fatigue damage.It is impossible to predict the actual service life and reliability of hoisting ropes,which seriously affects the safety and reliability of coal mines.In this paper,a self-made steel wire fretting fatigue tester was used to carry out the wire fretting fatigue experiment,and the evolution law of the wire wear profile and crack propagation depth with the number of cycles is revealed.By combining the finite element method,tribological theory,fatigue and fracture mechanics,fretting fatigue wear evolution model,crack initiation prediction model,and crack propagation prediction model were constructed.A fretting fatigue life prediction model considering wear,crack initiation and propagation was proposed,and the effect of fretting fatigue parameters on the fretting fatigue life of steel wires was revealed.Combining wire rope bending fatigue experiments and finite element analysis,the failure mechanism of wire rope bending fatigue under variable tension was revealed,the hoisting rope life prediction model based on fretting fatigue was proposed.The results show that: the wear profile size and crack growth depth of the steel wire increase with the number of cycles.The fretting fatigue life of the wire predicted by the model and the verification experiment result has a relative error of 10.1%,the prediction result is accurate.The wear volume of the wire is mainly related to contact load and fatigue load.Contact load,fatigue load,cross angle between steel wires,and wire diameter all affect the fretting fatigue crack initiation life of the wire.The main influencing factor of the fretting fatigue crack propagation life of the wire is the fatigue load.The increase in the tension of the wire rope and its amplitude will shorten the bending fatigue life of rope.The service life prediction result of the hoisting rope is in line with the regulations.