Fatigue limit estimation of metals based on the thermographic methods: A comprehensive review

Infrared thermography has been under review in the last 30 years due to its versatility and potential in the detection of the thermal signature associated with intrinsic energy phenomena due to dissipative processes, specifically those relying on mechanical fatigue. Nowadays, it is a well-established technique that can support mechanical and structural engineers to implement a damage-tolerant design, assess the residual life, and finally characterize the fatigue behavior of materials. The aim of this work is to review all thermography-based approaches and procedures for fatigue limit estimation by rapid tests, drawing considerations on the applicability of thermal methods in fatigue assessment of mechanical components, proposing the capabilities of different thermal indices in fatigue assessment, and discussing the pros and cons of each method as well as the open points. On one hand, this review intends to sum up what has already been done in the field; on the other hand, it provides a guideline to direct new researches toward issues that should be resolved or understood.