New specimen and horn design for combined tension and torsion ultrasonic fatigue testing in the very high cycle fatigue regime

Ultrasonic fatigue testing under multiaxial loading conditions on a railway wheel

“…Following the initial specimen idea described in [9] with new relations between dimensions, several combinations are tested in a finite element software until one final combination has both the mentioned resonant modes, figure 2, with similar frequency and close as possible to the middle range of the transducer frequency of 20 kHz. After machining the specimen in accordance, they are black painted for temperature measurement, being with a thermal camera or with a pyrometer.…”

“…As described by the research [9], the multiaxiality is achieved by exciting the specimen not in one but two resonance modes, the first axial and the third rotational mode. This is possible by the special horn geometry capable of transforming part of the axial displacements in rotation, thus transmitting simultaneously axial and rotational excitation to the specimen.…”

“…Very few examples of multiaxial ultrasonic fatigue testing can be found, one worthy mention is the test created by Palin-Luc able to achieve biaxial bending stresses [6]. In this study the fatigue analysis of a worn out railway wheel is performed, focuses on the development and testing of an ongoing research of a multiaxial tension/torsion ultrasonic fatigue machine [7,8,9].…”

Cruciform specimens' experimental analysis in ultrasonic fatigue testing

“…With the development of ultrasonic fatigue testing, many new trends capable of applying different stress combinations than the first uniaxial tension/compression were created, like uniaxial bending and biaxial bending, torsion, or even combined multiaxial tension/compression with torsion …”

“…With the development of ultrasonic fatigue testing, many new trends capable of applying different stress combinations than the first uniaxial tension/compression were created, like uniaxial bending 12 and biaxial bending, 13 torsion, 5,14 or even combined multiaxial tension/compression with torsion. 15,16 In this work, ultrasonic fatigue tests were conducted to analyse cruciform test specimens that were purposely designed to induce an orthogonal biaxial state of stress at its centre when resonating at 20 kHz, as initially proposed by Montalvão and Wren. 17 The designs for VHCF are based on other cruciform specimens that have been created and optimised by several authors for the study of fatigue for this type of complex biaxial stress cycle in conventional nonultrasonic machines.…”