Abstract
Abstract Torsion fatigue tests have been conducted at 20 kHz ultrasonic fatigue testing systems, and compared to the torsion fatigue data generated on 35 Hz conventional fatigue test machine to determine if there are any frequency effects, for steels including D38MSV5S steel and 100C6 steel. Results indicated that the S–N curves exhibit decrease in fatigue strength beyond 107 cycles. The initiation in the Gigacycle regime is related to defects sometimes located beneath the surface which shows a competition between the maximum shear at the surface and the stress concentration under the surface, even in torsion.
Highlights
Recent work using ultrasonic test system has shown that many materials, including some steel, aluminum alloys and titanium alloys, exhibit a sharp decrease in fatigue strength between fatigue lives of 106 and 109 cycles [1,2,3,4,5].it is much more difficult to carry out fatigue tests in torsion in the gigacycle regime where the fatigue life of many car components is ranging The first step is to design a good device, which is an important part of this study
Cast aluminum AS5U3G-Y35, D38MSV5S steel and 100C6 steel are three kinds of alloys used in automotive engine components
The S-N curves show that fatigue failure of the three alloys may occur between 106 and 1010 cycles For D38MSV5S steel, fatigue lifetime increases as the stress amplitude decreases in the life range of 104~2x106 cycles
Summary
Recent work using ultrasonic test system has shown that many materials, including some steel, aluminum alloys and titanium alloys, exhibit a sharp decrease in fatigue strength between fatigue lives of 106 and 109 cycles [1,2,3,4,5].it is much more difficult to carry out fatigue tests in torsion in the gigacycle regime where the fatigue life of many car components is ranging The first step is to design a good device, which is an important part of this study. Due to some components subjected to low amplitude, high cycle, high frequency cycle loading in their working service, it is of interest to investigate fatigue behavior and fracture mechanism of the alloys in very high cycle regime.[2]. It is necessary to investigate the torsion fatigue performance in very high cycle regime. Since 1993, Stanzl-Tschegg S.E and et al [1] designed and constructed an ultrasonic torsion fatigue test system at a frequency of 21 kHz, it began to investigate torsion fatigue behavior of alloys. To achieve the goal of determining the fatigue strength under torsion loading, a novel piezoelectric torsion fatigue testing machine was developed, in our laboratory, in which a torsion fatigue specimen is driven into a 20kHz high frequency resonance mode. The SN curve, the origin of the fatigue crack, and the fatigue characteristics are discussed up to 1010 cycles
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