Study On The Influence Of Exciting Frequency To Welding Residual Stress

The reason why crackings and deformations often occur to weldments is that there are many welding residual stress within them,which have a great impact to weldments'dimensional accuracy and service life.In order to eliminate the adverse impact,there are generally two ways to eliminate the welding residual stress in engineering:the natural stress relief(NSR) and the thermal stress relief(TSR).The cycle of NSR is too long, and too low efficiency, and too big location.TSR is not only large-energy-consumption, high-cost, serious-environmental-pollution and restricted by the furnace size, but also easy to produce oxide, resulting in deformation of the workpiece during aging,even can not conducted or costly for some large-scale structures.VSR overcome the above drawbacks,and have a better impact to dimensional accuracy,structural stability and fatigue life of the weldments,but due to the lack of scientific basis for the selection of excitation parameters,there are still some shortcomings.The exciting frequency is the key technologies parameter, the domestic and foreign numerous scholars have conducted the massive experimental study, but research is not systematic, conclusions are unconsistent.This article takes the low-carbon uniform thickness rectangle thin steel plate weldment as the main object of study,from both theoretical and experimental angles,implements a study on the effects of different vibration frequencies on the reduction extent of welding residual stress systematicly.In theory, by experimental modal analysis technology,the frequency-amplitude frequency characteristic curve of the weldment is obtained which reflects the residual stress-exciting frequency relation of weldments.The mechanism that the different exciting frequencies to influence the residual stress is explained. In experiment, taking advantages of the experimental modal analysis technology and the the blind hole drilling method to measure natural frequency of the sample and welding residual stress of the measuring points respectively,this article analyzes and processes the two different datas before and after vibration of the specimen via curve fitting,then obtains a conclusion of the experiment study.A comparison of experimental results and theoretical conclusions shows good agreement,it is obvious that they lead to mutual conclusions.To sum up,the research conclusions of this article are as follows: the welding residual stress to be reduced is changed differently with different vibration frequencies which leading to the difference of dynamic stress's size and distribution in the specimen,the reduction extent of the stress is larger natural frequency than non-natural frequency and the reduction extent of the stress is larger low natural frequency than high-order natural frequency when used,the changing trend of the reduction extent of residual stress of the samples with vibration frequency and the trend of the amplitude-frequency characteristics of it show some similarity. At the same time,the vibration mode have a great impact on the resuction extent of welding residual stress.