Development of an ultrasonic fatigue testing system for gigacycle fatigue

Abstract

High cycle fatigue (HCF) in the range of 10 6 to 10 8 cycles and very high cycle fatigue (VHCF) in the range of 10 8 to 10 10 cycles are key design criteria for aerospace, automotive, military, transportation, and other industries. However, data gathering in the HCF and VHCF ranges is inefficient with traditional 50to 100-Hz servo-hydraulic testing machines. The development of high power piezoceramic actuators makes it possible to reliably conduct HCF and VHCF tests within a very short time frame at high frequency on the basis of the ultrasonic fatigue testing approach. An ultrasonic fatigue test machine operating in an axial mode shape of test specimens at 20 kHz was designed and built to investigate VHCF characterization of lightweight metal alloys. The experimental setup went through several stages of design and validation. Finite element analysis was employed to design three versions of an acoustical horn, a single half wavelength booster, and three types of nonferromagnetic samples. The developed ultrasonic fatigue machine was used to conduct fatigue testing of specimens made from 2024-T351 and 7075-T6 aluminum alloys to generate representative HCF and VHCF data. HCF and VHCF data for these alloys were found to be in good agreement with experimental fatigue data from the literature.

Fracture–Mechanical Assessment of the Effect of Defects on the Fatigue Lifetime and Limit in Cast and Additively Manufactured Aluminum–Silicon Alloys from HCF to VHCF Regime

“…When the threshold value for frequency deviation is passed, a fracture is detected, and the test stops. This compares to analogous failure detection mechanisms in [39,40]. Specimen heating is avoided by the…”

Very high cycle fatigue characterization of additively manufactured AlSi10Mg and AlSi7Mg aluminium alloys based on ultrasonic fatigue testing

“…The ultrasonic fatigue testing machine has been developed in‐house by the present authors to investigate HCF and VHCF of metallic materials 30 . The test machine configuration shown in Figure 1A was used to conduct fatigue testing of AlSi7Mg and AlSi10Mg specimens.…”

“…The present authors 30,32 provided design and development details of the ultrasonic fatigue testing system, for example, a power supply/signal generator, piezoelectric converter, horn, booster, test specimen, data acquisition and control systems. Readers can refer to detailed description for design iterations of the acoustic stack and technical aspects of generation, control and verification of vibration amplitudes and representative fatigue data validation in references 30,32 …”

“…The ultrasonic fatigue testing machine has been developed in-house by the present authors to investigate HCF and VHCF of metallic materials. 30 The test machine configuration shown in Figure 1A was used to conduct fatigue testing of AlSi7Mg and AlSi10Mg specimens. The testing machine shown in Figure 1B used a piezoelectric converter model CH-20C supplied by Branson with a maximum displacement of 20 μm.…”

“…Readers can refer to detailed description for design iterations of the acoustic stack and technical aspects of generation, control and verification of vibration amplitudes and representative fatigue data validation in references. 30,32…”