Issue 27

P. Hou et alii, Frattura ed Integrità Strutturale, 27 (2014) 21-27; DOI: 10.3221/IGF-ESIS.27.03 26 (2) All the fatigue damage indicators can describe the fatigue damage evolution process. The macro-phenomenon and internal microstructure evolution are associated by the energy theory. (3) The low error between the predicted fatigue limit and the traditional value demonstrates the reliability of the infrared thermographic method in predicting fatigue parameters of materials and components. (4) It is a fast and accurate technique for fatigue evaluation using various damage indicators resorting to the infrared technique. Consequently, the method may be used to identify fatigue damage status of structures in service in the future work. A CKNOWLEDGEMENTS he financial support of the Natural Science Foundation of China (Grant No.11072045) is gratefully acknowledged. Moreover, J. Fan would like to thank the China Scholarship Council for his research at Purdue University of USA. N OMENCLATURE R stress ratio ρ material density C p specific heat capacity a coefficient of linear expansion k heat conduction coefficient ψ Helmholtz free energy ε strain tensor α internal variables γ e external heat resource d intrinsic dissipation σ α stress amplitude σ m average stress σ ( x , y ) stress value at the point (x, y) σ SDS standard deviation of stress σ p predicted fatigue limit stress σ f fatigue limit stress Δ T temperature increment T 0 initial temperature T m average temperature Δ T s stationary temperature increment R EFERENCES [1] Zhang, L., Liu, X. S., Wu, S. H., et al., Rapid determination of fatigue life based on temperature evolution, Int J Fatigue, 54 (2013) 1-6. [2] Fan, J., Guo, X. L., Wu, C. W., A new application of the infrared thermography for fatigue evaluation and damage assessment, Int J Fatigue, 44 (2012) 1-7. [3] Fan, J., Guo, X., Wu, C., et al., Influence of heat treatments on mechanical behavior of FV520B steel, Exp Techniques, (2013) DOI: 10.1111/ext.12019. [4] Luong, M. P., Fatigue limit evaluation of metals using an infrared thermographic technique, Mech Mater, 28 (1998) 155-163. [5] Curti, G., La Rosa, G., Orlando, M., et al., Analisi tramite infrarosso termico della temperatura limite in prove di fatica, Conference Proceedings: 14 th AIAS Italian National Conference, Catania, Italy, (1986). [6] Fargione, G., Geraci, A., La Rosa, G., et al. Rapid determination of the fatigue curve by the thermographic method, T