Experimental Study On The Member Residual Stress Detection Method Of Hilbert-huang Transform Method

With the development of modern science and technology,people have more strict requirements on the structural stability and fatigue strength of components.Casting,forging,welding,cutting and other mechanical processing will make components have different degrees of residual stress in some extent,and the existence of residual stress will seriously affect the performance of the components.Therefore,Nondestructive,rapid,accurate,feasible method for the detection of residual stress of welded components has long been a research hotspot by scholars at home and abroad.According to the publicly available information,the Hilbert-Huang transform method has not been applied to the field of residual stress testing of components.In this paper,the Hilbert Huang transform method is used to study the detection of residual stress of components.Firstly,this paper presents the background and current research status of the topic,the basic theory of Hilbert-Huang Transform in detail.Based on the phenomena of mode aliasing among empirical mode decomposition method,using the overall average empirical mode decomposition method and the results show that this method is more accurate and effective.Then,the vibration characteristics of the single and multi degree of freedom system and their respective overall average empirical mode decomposition method are analytical studied.The highly corresponding relationship between natural vibration mode function and intrinsic mode function of mechanical system is obtained.Secondly,we use the B&K signal acquisition system to collect the vibration signal of untreated welded steel plates,Welded steel plates after the first and the second thermal aging treatment.The classic method of drilling is carried on testing welding residual stress among the three states above.The characteristics of residual stress distribution of welded steel plates under different stress states are obtained.Finally,Hilbert-Huang transform is used to analyze the collected vibration signal of the welded steel plates,obtain their respective Hilbert spectrum.in order to compare the difference of Hilbert spectrum of different vibration signals,the paper puts forward the judgment criteria: time amplitude frequency product.According to the Hilbert spectrum of the vibration signal in different states,calculate each time amplitude frequency product,then analyze the variation of time amplitude frequency product.Results show that: using the method of Hilbert-Huang transform and studying the Hilbert spectrum of time frequency product can accurately judge whether there is residual stress of the welded steel plates,and the detected results using the hole drilling method is used to validate this method,consistency of both,showing the feasibility and rationality of this method in the detection of residual stress of components.