Finite Element Analysis And Fatigue Life Research Of The Double Wishbone Independent Suspension With Torsion Bar

Suspension system is the main chassis assembly parts. In the course of driving,suspension has very important roles:1) Suspension transfer the force and torque be-tween frame(or body) and wheels;2)Suspension reduces impact loads from the pave-ment to the frame (or body), attenuation vibration which the road impact brings to theframe (or body), and ensure the ride comfort and security of the car. In the doublewishbone independent suspension with torsion bar, knuckle and upper and lowerwishbone are very important components, have great influence on the vehicle per-formance, and have bad stress distribution. If the suspension parts are broken in theprocess, it will cause a serious accident, so the study of suspension strength and dura-bility is of great significance.According to its’ requirements for strength and fatigue life, the paper takes themodel of the front double wishbone suspension with torsion bar coming from a schoolbus as the research object, combines with finite element method and fatigue lifeprediction theory, and discuss the following three aspects:(1) Established a torsion bar type double wishbone front suspension and carriedon the simulation analysis. Thorough understanding the front suspension structure of aschool bus, according to the3d model of front suspension to determine the parametersof suspension system, calculating the torsion bar spring stiffness and making torsionflexible processing, rigid-elastic coupling model of suspension is built; Calculate tireforce under three typical working conditions(braking, steering and largest verticalforce) in the process of the car, customize the static loads analysis, and get the forcesof knuckle.(2) The Strength analysis of suspension assembly. The finite element model ofsuspension assembly, which include knuckle and upper and lower arm, is established,mainly study the simulation method of ball joint between components, and add con-straints and loads. Then static strength analysis is carried out on the suspensionassembly under three typical condition; Results show that the maximum stress is farless than ultimate strength of materials and suspension satisfy the strength require-ment; Based on statics analysis, forces of ball joint position of knuckle is gained, andcompared with ADAMS simulation analysis results. (3) The fatigue reliability analysis of suspension assembly. Insight into thefatigue reliability theory, fatigue life analysis of suspension assembly was carried outusing the software MSC. Fatigue, and conclusion fatigue life and fatigue damage areaof suspension assembly under three typical conditions.