Fatigue Life Prediction And Structural Optimization Of High-capacity Xanthator Agitator Under Variable Load

The agitator of the xanthator is a crucial component for producing viscous adhesive fiber solution.It is composed of a spindle,support arm components,and spiral blades connected by welding.To improve production efficiency,the xanthator’s capacity and size continue to develop towards large-scale.However,during operation,the agitator is subjected to alternating torsional loads,and micro-cracks easily appear in the welded joint area,which can then extend into cracks and cause deformation or fracture of the spindle or spiral blades,seriously affecting the xanthator’s service life and safety.This article focuses on the fatigue failure of the ZHR139-A 50m~3 large-capacity xanthator agitator and proposes a fatigue life prediction method for the large-capacity xanthator agitator under variable loads.It analyzes the sensitivity of the key structural components and parameters of the agitator to its life,and then improves the design and optimizes the parameters of the agitator structure.The main research work and results of the article are as follows:(1)Analyze the structure of the ZHR139-A xanthator agitator and establish its CAD model using Solidworks software.Analyze the working process and characteristics of the xanthator,and study the weld defect of the agitator using similarity design method and analyze the reason for cracking in the welded joint area.(2)Based on the stress state of the agitator during operation,establish its CAE model on the ANSYS Workbench platform,and analyze the structural deformation and stress distribution changes during the operation of the agitator using the one-way fluid-solid coupling method,and analyze its time-varying characteristics of stiffness and strength.The calculation results show that there is an obvious stress concentration phenomenon in the welded joint area of the agitator support arm,and the stress amplitude at this location changes greatly,which may cause cracks or cracking.(3)Based on the Miner linear cumulative damage theory and nominal stress method,predict the fatigue life of the agitator under variable loads,and find that the dangerous life positions are all distributed in the support arm welded joint area,and the weld defects have a significant impact on the effective life of the structure.(4)To improve the effective working life of the agitator and alleviate the stress concentration phenomenon,propose a structural improvement scheme based on engineering practice experience,and then use the response surface optimization method to optimize the structural parameters.The maximum equivalent stress of the agitator structure was reduced from 110.55 MPa to 77.033 MPa,a reduction of 36.655%,and the effective working life was increased from 15.51 years to 22.8 years,an increase of47%.The results meet the expected performance indicators of the xanthator agitator.