Research For Round Bar Specimen Clamp Of Resonance Fatigue Testing Machine

With the development of the industrial revolution,vehicles,related vehicle’sdevelopment and application of large mechanical equipment in the production,whichoften happens failure between the moving elements.This makes the nominal stress ofdamage is lower than the yield strength and the yield limit, which has been plagued byengineers for years. Since the 19 th century, however, there was a new subject-fatigueand the subject has been applied to actual production practice and the development ofmore and more perfect.Resonance fatigue testing machine is indispensable for fatigue test.For resonancefatigue testing machine equipped with different forms of clamps,which can makedifferent tests such as thin and thick plate tensile test,three-point and four-point bendingtest,torsion test and commonly used high frequency voltage test.However,clamps in thefrequency fatigue test machine for a long period of time under alternating stress andhigh and high temperature,the influence of fatigue damage is produced.The paper mainly studies the damaged problem of round bar specimen clamp ofPLG-100 type resonance fatigue testing machine.Due to reasons such as manufacturingor testing process,clamp is prone to be damaged and influences the reliability of the datain the process of actual tests.Firstly, the reasons of the fatigue life for clamp thread canbe analyzed by several theories,including the error and the mechanics of the clamp,thenthrough the fatigue test to verify the reliability of the test data by damaged clamp.Using large-scale finite element analysis software ABAQUS to analysis clamp andspecimen structure,according to the problems of elastic-plastic and contact nonlinear ofclamp and specimen,analysis of various thread clamp screw stress and strain distributioncan be had,and sums up the uneven characteristics of clamp thread under axial load ofeach thread tooth.The finite element analysis results are consistent with the abovetheoretical analysis and fatigue test results,thread tooth of damaged clamp will producenon-uniform stress and stress concentration phenomenon and load distribution ofdamaged clamp force has larger heterogeneity.Due to damaged clamp,three projects are proposed to repair the clamp throughfatigue test.Test results showed that only the mosaic thread set of solution meets therequirements of the test and successfully obtains the linear correlation of linear part ofthe s-n curve.