The Finite Element Analysis And Calculation Of Fatigue Life About Torsion Bar Under Load

Torsion bar is the main elastic part for suspension system of Tracked Tank and Armored Vehicle,it plays a very important role in the suspension systm, it can be used to reduce the reaction of ground to the vehicle.It bears large stress,strain and impact,it may be fractured due to fatigue after a long time working and this is one of important factors that make the Armored Vehicle can't working.In this thesis,it applied mechanics theory,finite element method(FEM),fatigue theory to the research about the torsion bar,the primary accomplished contents are as follows:It applied theory of Elasticity , Plasticity and Mechanics of Fracture to systematic demonstration about theory of compulsive torsion in this thesis.The compulsive torsion technics has a very important influence on the life of torsion bar,the theoretical research about the work characteristic of torsion bar is done in the field of mechanics of Elasticity and Plasticity,the characteristic of load and unload are demonstrated in detail,the influence of the pre-torsion angle and the remainder stress to the load capacity of torsion bar are demonstrated too.It use FEM to analyse and calculate and select quad 4node and brick 8node element type to build the torsion bar FEM model, according to the real work conditions, one end of the model is attached fixed constraint,another end applied dynamic torsion stress,it use transient analysis method of FEM to the simulation and calculation about the dynamic response of torsion bar under load,according to the load-time spectrum ,ten load steps were loaded in 4.95 seconds,it finished the dynamic analysis about the torsion bar under random load spectrum,at last,the danger location that the torsion bar may be fractured is ascertained.To calculate the fatigue life, integrate FEM with fatigue theory.According to the result of FEM,combined the road condition with load spectrum,the calculation about the fatigue life of torsion bar is done ,the thesis use local stress and strain method to estimate the fatigue life of torsion bar.According to the load-time spectrum,use rain flow metheod to deal with it ,the local stress and strain are calculated through combining the material parameter with Neuber formula ,the fatigue life and fatigue damage are calculated according to the R.W.randgraph formula ,then using the Miner fatigue cumulate damage theory to calculate fatigue life.