Analysis on Fatigue Strength Reduction Factor of Reactor Pressure Vessel Flange Thread

Considering the model type,element type,numbers of grid and contact type,the mechanics property is analyzed and the theoretic fatigue strength reduction factor is obtained.The results show that the fatigue strength reduction factor peaks under the tension-compression bearing way which can envelope the bending bearing way and torsion bearing way.Meanwhile,it shows that the contact type has the greatest effect on the fatigue strength reduction factor.Under bonded contact type,the effect of mesh refinement is ignorable.With the increasing of grid numbers for hexahedral element,the fatigue strength reduction factor increases,and vice versa for the tetrahedron element.