الفهرس 
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Abstract
The main objectives of this research were the aero-structural, and fatigue analyses of a
small-scale H-rotor vertical axis wind turbine blades (VAWT) made from composite materials.
These objectives were studied with the focus of fracture behavior of joints manufactured from
composite materials. The H-rotor VAWT blades failure due to adhesive delamination in addition
to adhesive joint failure between skins were studied. Classical fatigue analysis using “Goodman
method” accompanied by the fracture mechanics theory using “Paris’ Law” was performed in this
study in order to estimate the blade life.
The small-scale VAWT is designed to be self-start and operate on a residential roof located
at Port Said-Egypt. The VAWT blades are made from S-2 fiberglass/ Epoxy composite. Detailed
stress analysis of the H-rotor VAWT blade with different wall thicknesses is discussed and
presented. The rotor blade design is based on the maximum values of deflection and bending
stresses at extreme loading conditions. Rotor blades made from Carbon fiber/ Epoxy composite
were also investigated in this study and the stress analysis results were compared with that of the
S-2 fiberglass/ Epoxy composite blades.
The results showed that the wind turbine performance was improved by 8 % when using
the NACA 0021 airfoil instead of the NACA 0015 airfoil. In addition, by designing the wind
turbine using 3 blades, the performance was improved by 24.4 % in preference to 4 blades and by
62 % in preference to 5 blades.
The structural analysis revealed that the S-2 fiberglass/ Epoxy composite material is
promising for manufacturing the VAWT blades counter to the Carbon fiber composites. Blades
made from Carbon fiber/ Epoxy composite subjected to higher values of maximum bending stress
and more deflection was caused to the blades than the S-2 fiberglass/ Epoxy composite blades at
different values of the tip speed ratio by a percentage ranging from 20 % to 85 % according to the
operating conditions and the blade thickness.
The adhesive delamination and adhesive joint failure between skins, the blade wall
thickness and the type of blade fixation can significantly shorten the VAWT blade life . According
to the modified Goodman method, The VAWT S-2 fiberglass/Epoxy composite blade will live up
to 3 x 1011 cycles, which satisfies the design criteria for the 20-30 years lifespan of the composite
wind turbine blades under fatigue loading. While in the case of blade damage due to adhesive
delamination the blade will live up to 3 x 105 cycles (almost 1 day) and 3 x 106 cycles (almost 11
days) if it is subjected to adhesive joint failure between skins.