Failure Analysis Of The Thrust Rod Retaining Ring For Heavy Duty Truck And The Structural Optimization Design

In the process of modernization construction in China,heavy duty trucks,as the important production resources and strategic materials,play an indispensable role in national defense construction and national economic development.To cope with the diversity of vehicle operating environment,the requirements,nowadays,on vehicle suspension system is lifted step by step.Automotive thrust rod is one of the key components of air suspension in a passenger car and key parts of balance suspension and air suspension in a heavy duty truck.The harsh condition and environment in which heavy duty trucks work result in the thrust rod failure.To find out the causes of an accident that a certain type of thrust rod ring runs out of the groove in a heavy duty truck and to put forward suggestions for product improvement,this paper,by attempting to use the finite element simulation method,obtains the theoretical cause and influencing factors for the failure of spherical joint of thrust rod,aims particularly at the structural optimization design of the product,and analyzes and verifies the optimized result.To start with,the paper presents the structure composition and characteristics of thrust rod,explicates the ejection behavior of thrust rod ring of heavy duty truck as well.Based on the characteristic of failure accidents,this paper analyzes and points out that the influencing factors causing the failure lie in the load,assembly dimension,machining tolerance and friction force.It is designed to establish the finite element model for spherical joint of thrust rod,set the load with the ultimate limits for all possible vehicle conditions,perform the relevant computation for reproducing the failure phenomenon,and conclude that the dimensional tolerance of end caps and the friction force are the primary causes of failure accidents by comparing the results of the analysis data.Furthermore,the design intends to regulate the finite element model.Considering the magnitude of tolerance and friction,it adds more load data about simulation force to reach the maximum similarity to the real road condition and obtains how different parameters impact the ejection of retaining ring through the finite element simulation calculation in terms of variables and parameters.Both theoretical derivation and test simulation verify the conclusion from the finite element analysis,on the basis of which the spherical joint of thrust rod is optimized in its structure design.Focusing on the optimized simulation calculation data,analyzing how the tolerance dimension,friction coefficient and pretightening force of spherical joint affect the ejection of retaining ring,under comparison with the implemented result of manufacturer,this design proves that the optimized structure can effectively lessen the failure accidents.This paper presents a research method and result which are of valuable reference to optimization of thrust rod as well as provide a novel thinking for process innovation in automotive manufacturing,i.e.it finds out the limitation and problems in current process with combining limited test data through the finite element simulation analysis.With the aid of finite element simulation calculation,the structure and process are improved with their effectiveness being proved.It acts as the guidance to the production test of product.The way most of tests are accomplished through simulation helps reduce the test cost,shorten product development cycles and enhance the effectiveness of product improvement.