Finite Element Analysis Of The Crack Stress Intensity Factor On The Fan Transmission Shaft Of The 3# Hydrogenation Reactor Air Cooler

Fans are used in various fields of national economy metallurgy,petrochemical,power,urban rail transportation,textiles,shipbuilding and other ventilation as well as a variety of places.As an important mechanical components in the process of power transmission of fan,drive shaft mainly plays the role of power transmission and motion.And it is prone to brittle fracture failure in the course of their work,leading to the shaft does not work which bring many enterprises big loss and even cause safety accidents.So to study the cause of brittle fracture of this kind of structure is of great significance.This research is from the project which is a research and development cooperation project with Sinopec Wuhan Branch.Always appears crack at the step of drive shaft in it’s process of long-term service work,which lead to the destruction of the shaft.Based on the situation of the No.3 fan drive shaft,which appeared cracking failure at the step in the actual project,in this paper we studied the issue that the crack extension lead to the fracture of shaft,carried out the macroscopic appearance analysis and microscopic examination of the fracture of the shaft.And then finite element method is used to study the stress intensity factor of elliptical crack at the step of the drive shaft.Through the establishment of the model of the three-dimensional crack and the assembly model,the fracture mechanics finite element analysis model of the drive shaft with elliptical crack is combined.When the model was modeled,the two kinds of transition modes,which are the right angle step and the corner step,was respectively set up at the joint of stepped shaft.Firstly,the stress calculation of the drive shaft with no crack at the step was carried out.Then,the stress intensity factor of the drive shaft with crack at the step was calculated.After comparing the calculated that does fillet can reduce the stress concentration problem,but also can reduce the stress intensity factor.At the same time,extending of the calculation of the model was conducted and the change of stress intensity factor at the crack tip was observed by changing different variables,including step height changes,fillet radius of curvature changes and the length of crack and crack depth changes.Besides,through analysis andcomparison,the variation law of stress intensity factor of the crack front node was drawn out.Through the calculation of this paper,the calculation results can be linked with other axial materials.No matter the depth and the length of the crack,the stress intensity factor can be calculated,and through comparing the fracture toughness of the material to judge whether the crack extension,so as to assess the safety of the equipment.So the research of this paper has important reference value to the design of mechanical parts.