Multiaxial Fatigue Life Prediction Method Study Of Complex-type Box Structure

Box-type structure is widely used in various industrial fields of production, and is the main carrier of building bridges, engineering, mining, ports, oil and other heavy machinery, so its importance is self-evident. And the majority of the bearing member in a multi-axis stress state, the The multiaxial stresses caused by fatigue damage is the main failure modes of the member. Therefore, Box structure multiaxial fatigue analysis is becoming a focus for researchers.Hydraulic support beam is a typical box-type structure, the complex of hydraulic support working conditions make the roof beams in the multiaxial stress state in most cases. In order to ensure the hydraulic support in this complex stress state can better complete the support work, its roof beams multiaxial fatigue analysis is particularly important.This paper firstly analyzed the dynamic of multiaxial fatigue theory, and elaborated the theory of fatigue life.The actual working conditions for hydraulic support, Pro interface-based local stress and strain applied to the top beam fatigue life under multiaxial stress state.Through the analysis of the external load characteristics of the hydraulic support, Top beam load cases are divided into top beam whole uniformly distributed load, central centralized load, concentrated at both ends of the loading, reversing under load and loaded on one side five categories. The top beam of the different conditions to be simplified by plane force model and space force model, and calculate the size of the load. By Finite Element Analysis of the top beam of the various conditions of statics,it can get the weak vulnerable points and the stress results used in the analysis of the fatigue life.In FE-Safe, the load spectrum file of the consolidated operating conditions can be prepared according to the hydraulic stand trial standards.The load step generated by statics analys and this load spectrum superimposed on each other, creating a Elastic Block required fatigue analysis. Material properties and multiaxial fatigue algorithm are selected, then the fatigue life of the roof beams is analyzed, finally come to life results and life safety factor. This study provide reference and basis for the fatigue life of the box structure analysis.