Temperature profiles obtained in thermoelastic stress test for different frequencies
International Journal of Structural Integrity
ISSN: 1757-9864
Article publication date: 6 February 2017
Abstract
Purpose
Maintenance is one of the most critical and expensive operations during the life cycle of metallic structures, in particular in the aeronautic industry. However, early detection of fatigue cracks is one of the most demanding operations in global maintenance procedures. In this context, non-destructive testing using image techniques may represent one of the best solutions in such situations, especially thermal stress analyses (TSA) using infrared thermography. The purpose of this paper is to access and characterize the main stress profile calculated through temperature variation, for different load frequencies.
Design/methodology/approach
In this paper, a cyclic load is applied to an aluminum sample component while infrared thermal image is being acquired. According to the literature and experiments, a cyclic load applied to a material results in cyclic temperature variation.
Findings
Frequency has been shown to be an important parameter in TSA evaluations, increasing the measured stress profile amplitude. The loading stimulation frequency and the maximum stress recorded show a good correlation (R2 higher than 0.995). It was verified that further tests and modeling should be performed to fully comprehend the influence of load frequency and to create a standard to conduct thermal stress tests.
Originality/value
This work revealed that the current infrared technology is capable of reaching far more detailed thermal and spatial resolution than the one used in the development of TSA models. Thus, for the first time the influence of mechanical load frequency in the thermal profiles of TSA is visible and consequentially the measured mechanical stress.
Keywords
Acknowledgements
The authors would like to thank the program NORTE-07-0124-FEDER-000035, POPH (Programa Operacional Potencial Humano), QREN (Quadro de Referência Estratégico Nacional) – Tipologia 4.2 promotion of scientific employment funded by the European Social Fund (ESF), and Ministério da Ciência, Tecnologia e Ensino Superior (MCTES). The authors also acknowledge the support of FCT through project grant PTDC/EME-TME/120331/2010 – combined experimental–numerical methodology for SIF determination.
Citation
Silva, A.J.R., Moreira, P.M.G., Vaz, M.A.P. and Gabriel, J. (2017), "Temperature profiles obtained in thermoelastic stress test for different frequencies", International Journal of Structural Integrity, Vol. 8 No. 1, pp. 51-62. https://doi.org/10.1108/IJSI-04-2016-0016
Publisher
:Emerald Publishing Limited
Copyright © 2017, Emerald Publishing Limited