THE EFFECT OF CYCLIC LOADING ON THE RESIDUAL STRESSES AND STRESS INTENSITY FACTORS

Abstract

The evolution of the fracture mechanics parameters for cracks in the vicinity of welded joints of aluminum plates, caused by the redistribution of residual stresses under cyclic loading, is considered. The investigations were carried out under uniaxial tension-compression of rectangular specimens along the welded seam for two loading programs with different cycle parameters. Residual stresses are determined by the joint application of the hole drilling method and measurement of the increment of the probe hole diameters along the main deformations by the method of electronic speckle pattern interferometry. A crack with its origin located on the contour of the probe hole is modeled for each specimen by a sequence of narrow incisions perpendicular to the welded seam. The values of fracture mechanics parameters are determined on the basis of the modified version of the Crack Compliance Method at various stages of cyclic loading without applying an external load. Residual stresses, opening at the crack tip crack mouth opening displacement (CMOD)RES, and Stress Intensity Factors for cracks in the residual stress field are shown related to the number of loading cycles. The presented results provide evidence of the effectiveness of the developed approach for evaluating the durability of welded joints of thin-walled elements of aviation structures.