Fatigue Life Calculation And Vibration Reliability Analysis Of Bridge Crane Reducer

The bridge crane has been widely used because of its small footprint and the ability to realize the lifting operation in whole workshop.For bridge crane with three-point support,due to its lack supporting point,big lifting weight,frequent starting and work high above the ground,vibration,fatigue and reliability has become an important factor restricting its development.As the key component of the bridge crane,the reducer has an important influence on the comprehensive performance of the crane.So the research on dynamic response simulation,fatigue life prediction and reliability analysis of the reducer has great theoretical significance and practical value for the vibration reduction and reliability of the bridge crane.The subject of this paper is from the project “Research and application of lightweight technology for bridge crane”(No.2015BAF06B02)in the National Key Technology Suppport Program of China and aims at bridge crane reducer.The research includes dynamic load analysis,fatigue life prediction,vibration characteristics analysis and reliability research.The main research work in this paper can be summarized as follows:(1)A dynamic analysis model of helical gear and shaft model of bridge crane is built to calculate dynamic contact load of helical gears and rolling bearings for the loading spectrum of fatigue life.A stiffness correction of time-varying mesh stiffness of helical gears algorithm is proposed.Compared with the result of ISO standard and finite element method,the proposed algorithm is verified as its results agree well with the others?.Meanwhile,the internal dynamic excitation of gear system can be acquired based on the correction algorithm,which provides the basis for the analysis of vibration characteristics.(2)Aiming at helical gear pair at input stage and spherical roller bearing at high speed section of bridge crane reducer,the loading spectrum of fatigue life analysis are acquired.Referring to the GL standard,the material's S-N curve of helical gear and roller bearing is calculated.According to the stress results of static contact analysis,the fatigue life prediction of helical gear and rolling bearing is conducted with ANSYS/ FE-SAFE based on fatigue cumulative damage theory.(3)The finite element model of bridge crane reducer is built,the internal dynamic excitations were imposed on the contact line of gear pair to analysis the vibration characteristic and predict the structural noise.The feasibility of the simulation method was verified by comparing with the experimental result.Meanwhile,the dynamic characteristic and structural noise were calculated with different gear parameters and structural parameters.(4)Parametric model of bridge crane reducer is established by ANSYS software.Select some material and dimension parameters as random input parameters,set the approach rate between excitation frequency and the natural frequency as output variables,the resonance reliability of reducer is obtained using response surface method;as the same,set the RMS value of vibration velocity and acceleration as output variables,the vibration reliability of reducer is obtained.At last,using the Monte-Carlo simulation technique for sampling,reliability and sensitivity of structure system is obtained.