Quantitative Thermographic Methodology for fatigue assessment and stress measurement

The Thermographic Method, which takes temperature increment as the fatigue indicator, enables to predict the fatigue limit of materials and mechanical components in a relative short time. This research paper advances this Quantitative Thermographic Method for residual fatigue life assessment and nonlinear stress measurement. The developed approach was used to assess the fatigue parameters (fatigue limit, S–N curve, residual fatigue life, applied stress) of a mild steel A36, achieving good predictions. Moreover, the lock-in thermographic technique was applied for analysis of stress concentration zones to specimens, made of the same steel, with central flat-bottom hole.