Research About Accurate Forecasting Of Geometrical Deformation Of Rear Axle In Complex Load Situation

Automobile is indispensable in the daily life, and the automotive industry is the mainstay of Chinese economy. The chassis bear the body of car and is the base of various functions, it directly define the safety, dirigibility, NVH performance and reliability. The rear axle is the one of the chassis assemblies, which have multi functions and bear complex load. The researches of rear axle and its applications are various, but still have many vacancies there. Take the rear axle, the important part of reducing speed for increasing torque. The forecasting technique of geometry deformation of rear axle, which will be studied in this paper, is based on the background of rear axle tightness.The final drive and axle shaft, as an important part of the drive train, must work in a well lubricating environment with sealed gear oil. Therefore the oil seal of axle shaft of rear axle must have outstanding tightness. To seal the lubrication oil it must form a linear oil slick about thickness of 0.003 mm between the oil seal and seal block. When the environment to form an oil slick between the seal lip and shaft is ruined, the gear oil will leak. But it is only allowed when less than 0.3mm. Because of the heavy load, that rear axle will bear, there will definitely be some deformations, which will affect the performance of the seal tightness when they occur by the mounting place of seal, and if the deformation is too big, the tightness will even lapse, to prevent the lapsing of tightness in the early stage of product developing, the accurate forecasting technique of automobile rear axle’s small scale deformation under complex load condition is very necessary. A method to accurately forecast the automotive rear axle assembly small scale geometrical deformation under complex driving condition is needed hence preventing the oil leakage by early developing stage.This paper explain a method, which uses a small amount of testing load information as input of load analysis, so called virtual iteration. By this method it is possible to forecast the load on the rear axle under complex driving condition, and built a highly reliable loading condition of rear axle, it is very necessary for an accurate forecasting of the small scale geometrical deformation of rear axle.Secondly it is the research about the mechanical model. Because of the complexity of the rear axle mechanical model, as it related to bearing, axle shaft, final drive, axle housing, their disposition, the system matching of different stiffness, all of them influent the small scale geometrical deformation in a very complicated way. It’s necessary to find a usable model in conceptual design stage, to truly function as prevention by design. In this paper Euler beam theory is used to build a indeterminate beam model to simulate the rear axle, to achieve a reliable and rapid design.At last a dynamical model based on finite element is built, and is researched about dynamic small scale geometrical deformation under phase step signal, impulse signal and measured vibration signal, summarize its pattern, at the end achieve the purpose of accurately forecast by complex load situation.