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RESEARCH PRODUCT

Fatigue Crack Growth for Different Ratios of Bending to Torsion in AlCu4Mg1

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The paper contains the fatigue crack growth test results obtained under proportional bending with torsion in AlCu4Mg1 aluminium alloy [1]. Specimens with rectangular cross sections and dimensions: length l = 90 mm, height w = 10 mm and thickness g = 8 mm were tested [2]. Each specimen had an external unilateral notch with depth 2 mm and radius ρ = 0.2 mm. The tests were performed under the stress ratio R = −1. The notches in the specimens were cut with a milling cutter and their surfaces were polished after grinding. The tests were realized on a fatigue test stand MZGS-100 where the ratio of torsion moment to bending moment was \( M_T (t)/M_B (t) = tg\alpha = \sqrt 3 /3,1{\text{ }}and\sqrt 3 \) (Fig. 1) and loading frequency was 29 Hz. The total moment \( M(t) = \sqrt {M_T^2 (t) + M_B^2 (t)} \) was generated by force on the arm 0.2 m in length.