Fatigue Analysis Of Suspension Structure Based On Actual Load Spectrum

With the growing scale of China’s automobile market and the increasingly fierce market competition,users have higher requirements on the reliability of automobile products.Besides the traditional static strength design,fatigue life has also become an important indicator in the development of automobile products.Suspension assembly with sub-frame is a very important system in the automobile.In the actual road driving process,the suspension system needs to bear the action of alternating load due to the change of road conditions,which leads to the suspension parts are the most likely to produce fatigue damage parts.In this context,this paper takes a Mc Pherson front suspension with sub-frame as the research object,and carries on the strength check and fatigue analysis to the lower arm and sub-frame of the suspension,as well as the fatigue analysis to the rubber bushing at the junction of the two.Firstly,low-pass filtering and deburring signal preprocessing are performed on the load spectrum collected from the test site in LMS tecware;The pseudo damage value of the pretreated load spectrum is calculated,and the load spectrum is compressed and edited based on the damage time history editing method to shorten the fatigue analysis time.In ADAMS/ car,a multi-body dynamic model including Mc Pherson front suspension,multi link rear suspension,steering system,powertrain and body system is established.The load spectrum after compression editing is used as the input of wheel center for multi-body dynamic simulation,and the dynamic loads of lower swing arm,sub frame and rubber bushing connection point are solved as the input of fatigue analysis;The ultimate static load at the joint of the lower swing arm and the sub frame under the limit conditions is simulated and solved as the input load for strength check.After obtaining the working load for fatigue and strength calculation,the finite element models of the lower swing arm and the sub frame are established in Hyper Mesh,and the ultimate static load is extracted as the load,and the inertia release method is adopted for strength check;The unit load is applied to the finite element model of the lower arm and the subframe,and the unit stress results are imported into the ncode software.The fatigue analysis is carried out based on the nominal stress method and the extracted dynamic load;According to the strength analysis results of the lower arm,the structure of the stress concentration part is improved.After the improvement,the strength check and fatigue analysis are carried out again.The results show that the design requirements are met.In ABAQUS,the best constitutive model was fitted based on the uniaxial tensile and plane tensile mechanical experimental data of rubber material.The finite element model of rubber bushing was established in Hyper Mesh.The dynamic stress-strain analysis was carried out in ABAQUS software combined with the extracted dynamic displacement load.The analysis results were imported into Fe safe software for fatigue calculation based on the fatigue crack growth theory,The results show that it meets the design requirements.