Influence Of Contact Surfaces On Fretting Fatigue

The vast majority of mechanical parts,are working under cyclic loading,and micro fatigue is common mechanical components,such as pin connections,bolts and dovetail joint.Important in aerospace industry,nuclear industry and other industrial departments,micro fatigue is one of the main reasons for the failure of some matching parts.Compared with the general fatigue,in fretting fatigue,due to the effect of micro wear accelerated the damage of material,make the whole component fatigue failure,and even caused serious casualties.So for fretting fatigue life of study has certain significance.In this paper,by studying the different contact area waiting for picture of fretting fatigue life under load and crack initiation mechanism,and with the help of finite element on the comprehensive analysis.In this paper,the main research results are as follows:First motion of dovetail joint structure was designed experimental sample,implements the plane and contact form,specimen compact increased rigidity,improves the load frequency,improve the efficiency of experiments.Secondly establish finite element model of micro fatigue different contact area,contact area was respectively 31.8,31.8 was,was 38.8.Using a large number of finite element calculation,the paper analyzes the three kinds of contact area of the contact surface under the condition of stress strength,stress direction of X,Y direction stress,shear stress,strain and stress amplitude distribution of crack initiation and propagation.Research shows that in the contact area,the maximum stress intensity appears at the end of the grooved surface,contact area is smaller,the greater the stress amplitude,determine the direction of crack initiation and extension at the same time.Finally through the resonant high-frequency fatigue testing machine,make the dovetail joint specimens under maximum load for 5 KN and minimum load of 1 KN between fatigue experiment,obtained under different contact area,all specimens of fretting fatigue life and crack initiation location and direction.Consistent with the finite element analysis,at the same time won the S-N fretting fatigue life curve.From finite element analysis combined with experiments,the paper analyzes the size of contact area influence on micro fatigue properties,and quantitative analysis of the contact area and the relationship between the maximum stress amplitude,got from the experiment S-N micro can be by stress amplitude fatigue life curve,determine the contact area with life.It also through other structure combined with the contact area of fretting fatigue more detailed quantitative research.