Blade materials, testing methods and structural design - Wind Power Generation and Wind Turbine Design - page 460

be reduced if quality control and damage assessment methods are improved. The
reduction of safety factors could lead to an increasing amount of damage evolution
in wind turbine blades in service. The safely level can nevertheless be maintained
or increased if structural health monitoring (SHM) techniques are used. The per-
spective is that the turbine blades will be equipped with a suffi cient amount of
sensors that enables the detection of damages with high fi delity. The extra costs of
the SHM sensors and systems may be less than the cost savings by skipping the
regular service inspection, at least for large offshore wind turbines, where access is
diffi cult and costly. The potentially earlier detection of damage by SHM will give
the owner of the wind turbine the possibility to inspect, repair or replace the blades
before the damages become serious. The cost savings come mainly from the fact that
the vast majority of the blades are not expected to develop signifi cant damages; with
the use of SHM, these blades would not require any manual inspection.
From a knowledge point of view, it is envisioned that the future developments is
towards a better understanding of the damage evolution at a smaller length scales,
leading to a better, more complete and more fundamental understanding of the dam-
age evolution in composite structures. This opens the possibility for the development
of larger and better, more damage tolerant materials.

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