Analysis And Research On The Torsion Rear Axle Fracture Of A Sedan

Along with the enormous growth of the automotive industry, the requirements of both automotive OEMs and consumers for vehicle performance quality become more and more critical. Thereof, vehicle reliability has become one of the most important topics in vehicle development. The suspension system plays an important role among the entire vehicle systems and it’s one of the important systems which guarantee ride & handling, safety and off-road traffic ability performance. The technical conditions and reliability of the suspension system influences the vehicle performance developing and safety under extreme working conditions. They are also key indicators to evaluate vehicle quality.This article took the twist beam rear axle of one sedan as the object of research and carried out the case study of that sedan’s rear twist beam fracture phenomenon. On the basis of looking up into massive domestic and foreign literatures, relevant case studies of car suspension fracture and corresponding analysis methods were collected and compiled. Considering the fracture characteristics of that sedan’s twist beam, the FEM method has been utilized and the Benchmark analysis method has also been introduced in order to research and study the root cause which leads to that twist beam’s fracture as well as the optimization and improvement measures. A finite element model of that rear twist beam has also been created in order to validate the optimization.The strength analysis was carried out in four extreme working conditions including braking,steering,impacting and testing, in order to check whether the stresses in those four conditions exceed the allowable stress for that material resulting in the fracture of twist beam rear axle. After FEM and Benchmark analysis, the cross section of the transition area of that twist beam was optimized and redesigned to reduce the stress of the critical section of that twist beam and the material was improved, so that the reliability of that twist beam under various loads of complicated working conditions could be guaranteed and the general requirements of consumers for that sedan could be fulfilled.The FEM simulation and Benchmark were carried out again on the optimized model. The comparison of the twist beam structural strength before and after the optimization showed that the optimization had accommodated better local structural strength than the original design. The structural strength after optimization is even better than another twist beam of the same structure. The Feasibility and rationality of this optimization scheme were double checked by the component tests and whole vehicle reliability test.By Benchmark analysis, failure analysis and FEM, this article discussed about the root cause of the fracture of a twist beam and the corresponding failure mechanism. It provided intuitive data for the optimization, improvement and failure prevention of twist beams. In summary, the research of this topic explored a method of analyzing the twist beam fracture and preliminarily discussed about the Feasibility of gradually establishing data bases through Benchmark for vehicle systems to provide reference information for engineers who are engaged in research and development of automobile twist beams. Key Words: Automobile Chassis; Twist Beam; Benchmark; Finite Element Analysis.