Environmental Engineering Reference
In-Depth Information
Figure 12-1. Typical pattern of design drivers for the primary structural and mechanical
components in a HAWT.
[Boeing 1988]
HAWT blades, hubs, and turbine shafts are subjected to full reversals of a large dead
load once each rotor revolution. These large
gravity loading cycles
are seldom, if ever,
sustained by other fabricated and jointed structures. They are normally carried only by one-
piece precisely-machined components, such as vehicle axles. We can quickly estimate the
number of gravity cycles that a HAWT rotor must sustain in its lifetime by assuming a typical
Figure 12-2. Schematic S-N curve illustrating the severity of wind turbine fatigue
requirements compared to those of other structural systems.
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