3. Fatigue monitoring
The methods for fatigue monitoring for the Light Aircraft must differ from the systems which can be developed for and used on large transport planes. The indicator must be an autonomous, self-data-registering unit, miniature and lightweight.
All these requirements meets the Surface Relief Fatigue Indicator (SRFI).
Fatigue process for some metals is accompanied by formation and evolution of the surface deformation relief – the pattern of surface extrusion, intrusion, persistent slip bands (Fig. 1) [5]. The deformation relief is a three-dimensional structure.
The pure aluminium due to its plasticity react on deformation by the exhibiting surface relief. Pure aluminium is not used as constructional material, but it is often used for the protection of aluminium alloys against corrosion being clad layer of so- called Al-Clad aluminium alloy. The 2024-T3, 7075-T6 are well known examples of Al-Clad alloys used in the aviation industry.