Infrared thermography and experimental analysis in mechanical engineering

In the design and development department, the mechanical engineer designs the overall architecture of an industrial product, chooses technical options and carries out numerical and experimental simulations to subject materials, parts and structures to different types of loading. As experience is often considered the best teacher (usus magister est optimus), experimental analysis offers a convenient means of understanding, identifying and drawing out the main themes of industrial engineering, and providing solutions to the mechanical problems encountered while respecting sustainable development.

This requires a clear and coherent physical basis for the realistic validation of mathematical or numerical models of the problem. These are obtained by detecting, identifying and analyzing concrete problems linked to the irreversible and dissipative processes responsible for aging, damage, degradation, fatigue and failure of materials and structures under load.

Infrared thermography offers a non-destructive, non-contact technique that can be used in real time and is easy to implement to verify dimensioning hypotheses. It is of interest to many mechanical engineering disciplines, such as aeronautics, biomechanics, biomedical technologies, sports engineering, civil engineering, earthquake engineering, automotive engineering, technological innovation, intelligent materials and structures, building thermics, space technologies, etc.

The applications of infrared thermal methods have been the subject of numerous publications over the last few decades, thanks to constant and significant improvements in thermographic equipment, aided by ever more powerful microcomputers. They are based on heat transfer mechanisms. A great deal of research has been carried out to characterize various metals and non-metallic materials, subjected to fracture, non-destructive testing or vibration, or to detect plastic deformation in crack propagation under monotonic or repeated loading on test bodies, as well as the damage or fatigue mechanisms that precede fracture.

This method of inspection is based on the observation of a thermal map on the surface of the specimen under examination. The amount of energy emitted by infrared radiation depends on the thermal effects generated by thermomechanical coupling and developed under load. The use of digital thermal image processing techniques enables appropriate discrimination of the thermomechanical phenomena to be detected and analyzed correctly within a coherent theoretical framework.

The results obtained highlight a differential infrared thermographic technique and show that a realistic interpretation of the thermomechanical phenomena detected leads to innovative and varied applications...