Influence of microdamage structure on fatigue resistance of metal functional material

Abstract

The role of the collective behavior of defect ensembles at the crack tip and the laws of fatigue crack propagation in aluminum-magnesium alloy AMg6 have been studied under conditions of symmetric tension-compression gigacycle loading at 20 kHz using ultrasonic fatigue testing machine Shimadzu USF2000. 3D New View 5010 interferometer profiler high resolution data of defect induced roughness in the crack process zone under fatigue crack path revealed the existence of two characteristic scales: the scale of the process zone and the correlation length that is the scale when the correlated behavior of defect induced roughness has started. A mathematical model allowing the assessment of fatigue resistance of functional metal material on the basis of the analysis of loading parameters and the resulting fracture surface is developed. Analyzing the image by means of the wavelet-analysis, the basis parameters of a destruction surface are allocated. Based on the analysis of the destruction surface characteristics and the corresponding loading parameters, the fatigue life of the functional material is evaluated. For the solution of the problem, the elements of the fuzzy sets theory are used.