Fatigue Life Prediction And Experiment Scheme Design For Steel Wire Ropes

The steel wire ropes are widely used in engineering area.Disastrous accidents would happen if failures occur in steel wire ropes.Thus,it is vital to do researches on the damage assessment and service life prediction of steel wire ropes.This dissertation systematically investigates the application problems on the damage assessment and life prediction theories of steel wire ropes in aspects of configuration mechanics,data analysis and experiment design.Firstly,this paper proposed an absolute symmetric model for products with a sophisticated symmetrical structure,based o n which the hierarchy damage assessment method for steel wire ropes is established.Afterwards,by applying the experiment data of steel wire ropes,the feasibility and superiority of this method is validated thorough comparing with the 3D finite element(FE)analysis method.Additionally,this paper gives a primary approach for the design of the fatigue life experiment of steel wire ropes according to the data requirement of hierarchy damage assessment method.The main contents are as follows:1.Both analytical and numerical methods were combined to propose a universal damage assessment model for products with a sophisticated symmetrical structure.This new model is not confined by the material,structure and manufacture technological conditions,and it can b y widely used to calculate the relationship of the load supported by the whole product and the stress in the components in solving the mechanical analysis problem.This paper also gives feasible validation methods for the model proposed.2.Take a filling typ e steel wire rope as example to apply the hierarchy damage assessment method,the mechanical relationship between the steel wire and the strands is verified by using the specific test scheme and test data.The method is further demonstrated with the 3D finite element(FE)analysis result.A finite element fatigue prediction method is also given as a comparison.FE models verified that the theoretical model can precisely describe the contact pressure distribution in radical direction.The phenomena and laws of free-edge effect were investigated with numerical methods.Real impact test data of the entire cable is applied to verify the load-life curve of the whole wire rope.On the condition that it is difficult to carry out the entire cable fatigue experiment,this paper provides a strategy to calculate the load-life curve with strands experiment data.3.According to the hierarchy damage assessment results,the simulation accelerated fatigue experiment of steel wire ropes is designed and carried out under four levels of constant load.The experiment scheme is optimized and the optimal fatigue experiment scheme should be combined with the hierarchy damage assessment method to get a more accurate and reasonable fatigue life prediction result,which could also give guidance for further fatigue life prediction of steel wire ropes.