Fatigue Analysis And Life Prediction Of A Loader's Drive Axle Housing

As a key component of a wheel loader, drive axle housing sustains various forces and impacts both from road and the vehicle itself. The stiffness and strength of the axle housing is of great importance for the gears of reducer and differential meshing properly. It is also very important for the proper functioning of the axle. The wheel loader's working condition is very complex, so the axle housing suffers random dynamic loads. Therefore, the main failure mode of the axle housing is fatigue, which is caused by accumulated damage under long-term cyclic loading. With the major project of Zhejiang Science and Technology Department"Key technologies research of wheel loader's drive axle and its industrialization"(2009C11111), this paper analysis and estimates the fatigue life of the drive axle housing of ZL50 wheel loader. The main contents are as follows:1) A three-dimensional solid model of the axle housing is built via CAD software UG? and is meshed via pre-processing software HyperMesh?. The CAE model of the housing is then imported into a CAE software ABAQUS?. Strength analysis of the axle housing both in bench test condition and wheel loader's full loaded condition are carried out using finite element method, and stress distribution of the housing are obtained respectively. The axle housing surface is covered by a very thin level of shell elements, which provides a more accurate surface stress for fatigue analysis. The housing's natural frequencies obtained by modal analysis are compared with load frequency of bench test, the results shows that using quasi-static method to estimate the housing's fatigue life is reasonable.2) The load spectrum test program is determined based on the results of axle housing strength analysis. The load histories of the axle housing are acquired using strain gauges. Detailed analysis of the acquired stress spectrum is carried out. Rain flow counting processing of the stress spectrum is then carried out via nSoft's data processing module. Rain flow/damage histogram and damage history of each measuring point are obtained.3) The fatigue life of the axle housing is calculated using Miner's law via nSoft's fatigue analysis module. Life distribution of the axle housing is obtained by using quasi-static method and stresses distribution acquired from CAE strength analysis. Life prediction based on measured stress spectrum is also carried out.4) In order to investigate the influence of the weld on the axle housing's fatigue strength, fatigue life prediction of the weld joint is carried out. In accordance with BS7608 standards, both stresses acquired by test and finite element analysis are used to estimate the fatigue of the weld joint. Both results show that the fatigue strength of welded structures is significantly lower than the fatigue strength of the base metal. This matches the truth that the fatigue strength of the welded structures generally depends on the weld joint's fatigue strength.The load spectrum test/analysis method and the fatigue life estimation method in this paper also provide a reference for other vehicle parts'anti-fatigue design. This research has practical significance and promotional value.