Experimental Research On Stress-Magnetic Intensity Frequency Spectrum Lines With The Load’s Change Of Circular Steel Tube

As the steel structure has many advantages,Steel structure buildings are widely used,however there are a lot of accidents occur,it causes people’s attention to testing on the steel structure in service,and through the testing,we can kNow working state of the steel structure in service,so that we can strengthen and repair them.but traditional steel structure detection technology is mainly based on the local strain deformation testing.According to its constitutive structural elements to determine the internal force or stress,but most of existing structures has been completed its deformation.It is difficult to use the traditional steel structure detection,and some times it is impossible.From the current research and application,the existing structure nondestructive testing applications in the actual project still have many problems,most of them are still need to be improved,the effect of the detection is unsatisfactory.Therefore a method which is not based on the local strain and accurate should be badly in need of raising.And this article conducted the research on Stress-Magnetic Intensity Frequency Spectral Lines with the load’s change of Circular Steel Tube.The dissertation adopt experimental method,made and improved the miniaturization sensor,studied theory of the magnetic induction of steel members changes with stress,build up experimental system,by changing the stress on the specimen,we can change the magnetic intensity and get the experiment dates about stress and induced electromotive force under each frequency in the the horizontal direction and the vertical direction.We also get the stress-magnetic intensity frequency spectrum lines which reflect the relationships about induced electromotive force,stress and frequency.The experimental result show that:in both direction,induction electromotive force gradually decreases with the rising of the compression stress level,broadly in line with the linear decreasing trend in the law,and in the vertical direction the decreasing range is more that of in the horizontal direction;the curve of induced electromotive force developed at frequency moves down on the basis of zero stress,the lowest point of the curve is on the 2kHz in both direction;at the same frequency,induction electromotive force gradually decreases with the rising of the compression stress level,but each of the decreasing amplitude are different.This article also builds the mathematics expressions for the axial compressed load circular steel tube at the same frequency state,using the induction electromotive force normalized frequency spectrum,established stress range comparison method and correlation coefficient method to extract the stress we need.The resolution ratio of the experiment is±30kN,the precision increased along with the increase of load level,and the high load level is that we cared about.