Abstract
As a high strength and commercial steel, Q420 is widely employed in many engineering applications. In this paper, a series of experiments was conducted to investigate the fatigue crack growth retardation mechanisms under mixed I–II mode overloads with loading angles 0, 30, 60 and 90°. The baseline of loading spectrum is a pure mode I cyclic loading with a mixed overload applied after pre-cracking. The results show that the crack path is always straight for each case. Both the retardation level and fatigue life decrease with the increasing loading angle. A combined model that considers the residual stress, plasticity-induced and roughness-induced crack closure effects was proposed to predict the fatigue crack growth rate and fatigue life. The predicted results agree well with several experimental results.
Published Version
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