Effect of test frequency on fatigue strength of low carbon steel

Noriko Tsutsumi (1) , Yukitaka Murakami (1) , Véronique Doquet (2)

1 Kyushu University
2 LMS - Laboratoire de mécanique des solides

Ultrasonic fatigue tests (test frequency : 20kHz) and conventional tension-compression fatigue tests (10Hz) have been conducted on annealed and 10% pre-strained specimens of 0.13% carbon steel. Small holes were introduced on the specimen surface to investigate the effect of test frequency on small crack growth. The dynamic stress concentration factor and the stress intensity factor under ultrasonic fatigue tests were checked to be almost the same as those of conventional tension-compression fatigue tests. However, the fatigue properties were dependent on the test frequency. Ultrasonic fatigue tests showed longer fatigue life and lower fatigue crack growth rate for the annealed and 10% pre-strained specimens. Slip bands were scarce in the neighborhood of cracks under ultrasonic fatigue tests, while many slip bands were observed in a wide area around the crack under conventional fatigue tests. In order to explain the effect of test frequency on fatigue strength, dynamic compression tests with Split Hopkinson Bars were carried out. The stress level increases substantially with the strain rate. Thus, the increase in fatigue strength might be, to a large extent, due to a reduction in crack tip cyclic plasticity during ultrasonic fatigue tests.

Mots clés: Fatigue; Ultrasonic Fatigue Test; Test Frequency; Low Carbon Steel; Stress Intensity Factor; Split Hopkinson Bar Test

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]

Noriko Tsutsumi, Yukitaka Murakami, Véronique Doquet. Effect of test frequency on fatigue strength of low carbon steel. Fatigue and Fracture of Engineering Materials and Structures, 2009, 32 (6), pp.473-483. ⟨10.1111/j.1460-2695.2009.01350.x⟩. ⟨hal-00870854⟩