Study On The Fatigue Reliability Of Vehicle-Mounted Rescue Hoisting Wire Rope Under Winding Vibration

With the domestic people’s living standards continue to rise in material terms,More and more people choose private cars as the main mode of travel,especially the rapid development of the domestic new energy vehicle market in recent years,resulting in car ownership climbing year by year.The rapid growth of the number of cars also brings many safety accident problems.In order to quickly respond and rescue the accident,the vehicle-mounted rescue hoisting system is gradually being widely used.The steel wire rope with excellent tensile properties and good transmission capacity is widely used in the vehicle-mounted rescue hoisting system.To cope with the needs of different lifting rescue,the hoisting wire rope working environment is random and the service conditions are complex that the dynamics and bearing performance evolution law of the hoisting wire rope is difficult to accurately describe.In addition,the hoisting wire rope is prone to tensile fatigue,contact fatigue and other failure phenomena under the long-term cycle of alternating tension or random load.Therefore,in order to maintain the reliable operation of the vehicle-mounted rescue hoisting system and protect the safety of life and property,it is important to carry out research on the dynamics and load-bearing characteristics of the hoisting wire rope and analyze the evolution of its fatigue characteristics to ensure its reliability.In this study,the vehicle-mounted rescue hoisting system is taken as the research object to study the dynamic characteristics and the load-bearing characteristics of hoisting wire rope under complex hoisting conditions and their joint influence on fatigue characteristics and reliability evolution laws are equally studied.The research results can provide useful reference for the theoretical analysis and design of hoisting ropes and the safe operation and maintenance of vehicle-mounted rescue hoisting systems.The main research contents and achievements of this thesis are as follows:(1)Considering the factors of wire rope winding,vibration and detachment in the hoisting system,the study on the dynamic characteristics of the hoisting system under the influence of winding and vibration is carried out.Based on Euler-Bernoulli beam theory and Hertz contact theory,a dynamic model of wire rope hoisting system is established by using virtual prototype technology to take into account the flexible characteristics of the wire rope.The evolution of hoisting wire rope dynamics under hoisting conditions was analyzed,and the influence of different motion parameters,material parameters,etc.on hoisting wire rope vibration characteristics,contact characteristics and transmission characteristics were discussed.The research results show that the modeling in this thesis can accurately describe the vibration behavior of wire rope winding under the influence of multiple factors.The lateral vibration of the wire rope in the hoisting system is more likely to cause larger vibration amplitude than the longitudinal vibration.Severe lateral vibration and large movement speed easily make the wire rope slip in the pulley and resulting in relative slip speed instability.Braking in the uniform speed stage leads to the largest change in tension of the hoisting wire rope.(2)Taking the single-strand hoisting wire rope as the subject of discussion.A highprecision mesh division method for spiral wire rope is proposed,and a spiral,locally encrypted mesh model is established.Under the load of tensile strain,the interwire contact behavior and load-bearing characteristics of the hoisting wire rope are analyzed.Based on the results of dynamic characteristics analysis,discuss the influence of hoisting wire rope movement on the load bearing characteristics under actual working conditions.The research results show that the point contact area of the inner side wire and the outer side wire appears obvious stress concentration and the maximum equivalent stress of the hoisting wire rope appears in this area.Under the influence of different lifting conditions,the stress,strain and contact pressure of the hoisting wire rope are changing all the time.An increase in hoisting acceleration and hoisting load will cause an increase in equivalent stress,equivalent strain and interwire contact pressure of hoisting wire rope.(3)In order to investigate the effect of repeated hoisting conditions,a fatigue model of hoisting wire rope with cyclic tensile alternating load is established.Considering the effect of mean stress,the fatigue characteristic finite element simulation is carried out by the high precision mesh model.The fatigue life distribution characteristics of hoisting wire rope under cyclic alternating load are analyzed.The influence of the danger zone of the interwire and material parameters on fatigue life is discussed.In addition,considering the influence of random load under hoisting conditions,the fatigue life model of variable amplitude cyclic load is established,and then the fatigue life evolution law of hoisting wire rope under the influence of different motion parameters and different hoisting conditions is discussed.The research results found that under cyclic tensile alternating load,the low life region is distributed in both ends of the hoisting wire rope and near the interwire contact area.The outer side wire is more likely to fatigue failure.The fatigue life of the hoisting wire rope increases with the increase of hoisting acceleration and maximum speed and the decrease of hoisting load.Applying pre-tension to the hoisting wire rope before hoisting can improve its fatigue life.The increase of damping coefficient and tensile stiffness coefficient will improve the fatigue life of the hoisting wire rope.(4)Considering the factors influencing the load-bearing characteristics and fatigue characteristics of the hoisting wire rope,based on the Six sigma Analysis module on Ansys Workbench,the reliability model of hoisting wire rope was established by the methods of response surface and Latin hypercube sampling.The reliability of the hoisting wire rope with elastic modulus,Poisson’s ratio and tensile strain load as input variables and maximum equivalent force and fatigue life as output variables was analyzed.The results of the study found that the reliability model established under this method is accurate and valid,and can provide methodological reference for other related structural reliability analysis.The modulus of elasticity and tensile strain of the hoisting wire rope are positively correlated with the maximum equivalent stress and negatively correlated with the fatigue life.Among the input variables,the elastic model has the largest influence factor on the maximum equivalent stress and the fatigue life.