Online nonlinear ultrasound imaging of crack closure during thermal fatigue loading

A thermal fatigue surface crack (6 mm deep × 23 mm wide) in a thick austenitic stainless steel plate is opened and closed with thermal heating and cooling cycles. This closing and opening of the crack is recorded with using fundamental wave amplitude difference (FAD) technique with 5 MHz 64 element phased array probe. In addition, the contact pressure and crack opening state at different time intervals were estimated using finite element (FE) simulation. In combination with the nonlinear output from the FAD and FE simulation gave insight at which level the contact pressure or the distance between crack faces prevents the contact acoustic nonlinearity (CAN) from happening. Predictably, no clear nonlinear response was recorded at crack face locations experiencing high contact pressure and on the locations where the crack could be considered fully open, as predicted by the FE simulation. Therefore, the FAD technique can be utilized within the constraints quantified in the paper.

Description

Funding Information: This paper was funded by the Finnish radiation safety program SAFIR2022 . Trueflaw contributed the thermal fatigue cycle for the flaw. All contributions are greatfully acknowledged. Publisher Copyright: © 2021 The Authors

Keywords

Crack closure, Fundamental wave amplitude difference, Nonlinear ultrasound, Thermal fatigue, Ultrasound

DOI

10.1016/j.ndteint.2021.102510

Citation

Koskinen , T , Kuutti , J , Virkkunen , I & Rinta-aho , J 2021 , ' Online nonlinear ultrasound imaging of crack closure during thermal fatigue loading ' , NDT and E International , vol. 123 , 102510 . https://doi.org/10.1016/j.ndteint.2021.102510

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202108118307

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[article-cris] Insinööritieteiden korkeakoulu / ENG

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