Research On Fatigue Life Prediction And Optimization Design Of Power Transmission System Of Wheel Loader Based On Load Spectrum Analysis

With the development of China's economy,wheel loader plays an important role in construction projects which include building operations,mine exploitations,irrigation works and so on.The traction performance,operation performance and economic performance of wheel loader are determined by the power transmission system.So the fatigue life prediction of components and the optimization design of parameters are of great significance for improving reliability,dynamic performance and fuel economy of vehicle.The reserch works about load spectrum have been carried out,which included data acquisition,signal processing,statistical analysis and so on.Based on load spectrum analysis,the fatigue life prediction and optimization design of wheel loader's powertrain system were studied.The main works are summarized as follows:Firstly,a test scheme for the load spectrum of wheel loader was set up.In view of working mode of wheel loader and structural characteristics of the powertrain system,test details such as typical working condition,operation mode,test prototype were planned.The test system was setup,which inluded selection of acquisition instruments,selection of sensors,layout of measuring points and so on.Secondly,in view of the shortcoming of low precision and long time consuming when operation sections are manually divided,a new method of computer recognition and division was implemented.Operation sections were divided as "driving section-shoveling section" through searching the extreme points of synchronous load signals in single work cycle after iterative smoothing filter.Thirdly,load spectrum was compilied according to the following steps,which included rain-flow counting method,determination of probability distribution function,frequency extrapolation,amplitude classification and wave center calculation.Based on one-dimensional program loading spectrum and the finite element analysis,the fatigue life of axle shaft was predicted using the Miner criterion.Fourthly,innovative design of power transmission system was conducted by working cycle data analysis.This paper describes a methodology using Matlab/Simulink for quantifying dynamic power deduction under different gears in order to characterize the hydraulic pump flow in dynamical systems.Meanwhile,the Pareto front was incorporated into this paper and several optimization methods were applied to find the trade-off relationship between dynamic efficiency and operation fuel consumption.Finally,a fragmented information management software was developed,which can carried out data management and application analysis based on wheel loader data,component data and load spectrum data.