Detection Of Fatigue Damage Based On Nonlinear Mixing Technology

With the continuous growth of the national economy and the development of materials science,machinery manufacturing and other disciplines,metal materials are more widely used in transportation,aerospace and other fields.In practical applications,metal materials tend to produce fatigue damage due to alternating loads.Fatigue damage is sudden,resulting in a sudden catastrophic accident.In order to ensure the safe use of metal materials,it is necessary to detect the internal fatigue damage.Compared with the traditional linear ultrasonic detection technology,the coaxial heterogeneous mixing method has the advantages of selectable detection frequency and position,and high detection accuracy.It has become one of the effective methods for detecting fatigue damage of metal materials.In this paper,6060-T6 aluminum alloy material is used as the research object,and the key technology of coaxial axial heterogeneous mixed frequency nonlinear ultrasonic detection of tensile fatigue damage is explored.The relationship between material damage and acoustic nonlinear coefficients is derived.For the problem that it is difficult to extract the amplitude of the mixed wave from the mixed wave,the mixed wave based on the phase inversion method and the total wave subtraction subtraction method is studied Extraction technology,the accuracy of the phase reversal method is relatively high through analysis;the effects of different types of cracks,mixing cross positions,fatigue test loading frequency,and sample shape on acoustic nonlinear coefficients are analyzed,and the relevant laws are obtained.It provides a basis for the nonlinear ultrasonic detection of fatigue damage of metal materials;the ultrasonic echo signals of different crack specimens were collected through experiments,and the nonlinear characterization of crack detection,crack width and slope identification was studied.The research of the thesis provides theoretical analysis and experimental research basis for the further research of the coaxial axial mixed frequency nonlinear ultrasonic detectiontechnology to detect the fatigue damage of metal materials,and also lays a solid foundation for the application of non-destructive testing engineering of fatigue damage of metal materials,Has a certain research value.