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.