Quantitative Thermographic Methodology for fatigue life assessment in a multiscale energy dissipation framework

• We develop a new thermographic method for fatigue parameter evaluation.
• A multiscale energy dissipation framework in the fatigue process is established.
• An original thermal parameter is proposed as a measure of fatigue resistance.
• The proposed method is verified by fatigue tests on metals and welded joints.

Energy dissipation is an important aspect in fatigue that is closely linked to the microstructure evolution across different length scales. In this work, a novel energy-based method is developed that takes advantage of the shakedown theory and multiscale concept. A key thermal parameter pertinent to dissipation rate is proposed as a measure of the fatigue resistance. It leads to an effective way to evaluate the S–N curve. Experimental verification is conducted through the fatigue tests on different materials and structures. Excellent predictions are achieved by comparing to the traditional time-consuming procedure.