Acoustic Emission Evolution Characteristics Of Q355qD Steel Under Static Tension And Fatigue Load

Q355qD steel is a kind of high-strength structural steel that is widely used in bridge construction.However,due to the fact that the steel often has congenital defects in metallurgy,rolling and welding process,and these congenital defects will be further deteriorated by the environment and load in the later operation and use process,resulting in structural damage or even collapse,major economic losses and casualties.Therefore,it is necessary to study a method of non-destructive testing for Q355 qD steel,which in turn identifies its damage,evaluates its remaining life,and prevents sudden damage to the structure.As an important nondestructive testing method,acoustic emission technology has an important application in bridge testing and monitoring.Based on acoustic emission technology,this paper explored the signal characteristics of Q355 qD steel specimen at different mechanical behavior stages in the process of static and fatigue tensile action.The details are as follows:（1）Based on the acoustic emission parameters and waveform analysis,the mechanical properties of Q355 qD steel under static load are analyzed,the distribution of acoustic emission events in different mechanical stages is obtained;According to the one-parameter analysis method and the k-means clustering analysis algorithm,the potential correspondence between the acoustic emission characteristic parameters and the mechanical stage of the steel is excavated.（2）Based on VIC-3D technology,the surface strain field of the specimen at different mechanical stages under static load is collected.The mapping relationship between acoustic emission signal and strain field is analyzed,laying a foundation for the evaluation of steel damage by acoustic emission technology.（3）According to the current commonly used fatigue evaluation methods to determine acoustic emission can be involved in the evaluation stage;the fatigue damage of steel is evaluated based on the characteristic parameters of acoustic emission,and the acoustic emission signal activity during fatigue damage is analyzed according to PCA algorithm.（4）Fatigue life of different types of specimens is calculated based on ABAQUS-CAE and Fe-safe software,It is concluded that the average stress,stress concentration and test error are the main factors affecting the fatigue life of the steel,which further verifies the accuracy of the test results.