Crack Propagation Analysis And Life Prediction Of A Hook

The hook’s primary purpose is to transfer vertical forces between locomotives and vehicles,as well as vehicles to vehicles.Its reliability is related to truck transportation safety.With the continuous development of my country’s truck railway transportation in recent years,the tonnage and turnover of transportation have continued to increase.The failure rate of car hooks has increased year by year,and most of them are cracking problems,increasing the risk of the safe operation of the line.Therefore,this subject analyzes its actual operating conditions,material parameters,and performance indicators for a certain type of car hook with cracks.Combined with the compiled car hook 9 fatigue loading spectrum,the life of a crack hook life is achieved.The main research content is as follows:The computation of the 3D crack types and stress strength factor of the hook is investigated using fracture mechanics theory,and the car hook structure crack is calculated using the mixed-type equivalent effect strength factor.The Newman-Raju formula was used to verify the accuracy of the accuracy of the stress intensity factor,and the error was less than1.4%.Use Solid Works software to establish a three-dimensional model of a car hook.According to the actual operating conditions of a car hook and the theory of finite element related theories,setting boundary conditions and dividing grids,stretching and compressing the hook tongue and hook body,respectively.In the case,multiple groups of simulation are determined to determine the weak structure of the car hook is the root of the roots and the tongue in the hook tongue.Based on the cracks of the sub-model technology,the embedded crack parameters are compared and analyzed to determine the parameter value.According to the total load of the car hook-the time course,the load amplitude value is divided into an unrequited interval method to determine the 9-level load of the car hook finite element.Finally,the shape ratio and position angle of the influencing factors of the surface crack expansion of the hook.A prediction method of a type of car hook fatigue cracking expansion life is proposed.According to the car hook 9 fatigue loading spectrum,the mathematical expression of the equivalent effect of a car hook at all levels,respectively.Based on the cumulative damage theory and the crack expansion rate model,it is predicted that under the actual service conditions of the hook,the cracks on the inner curved surface of a certain type of hook tongue expand from 0.35 mm to 78.6 mm,and the mean life of the hook is 9.16×10~5km,which provides a reference for the maintenance cycle of the hook.