Tapered FRP Reinforcement for Wind Turbine Blade Root Stress

The reinforcing layer is divided into multiple fiber layers (first through fifth fiber layers) with different orientations and reinforcement directions. Each layer targets specific stress components, creating a graduated reinforcement structure that transitions smoothly from the blade root to the non-reinforced area, eliminating sharp thickness variations and stress concentration points.

Different fiber layers are applied to different regions of the blade root portion based on local stress requirements. The first and second fiber layers address stresses in one direction, while the third, fourth, and fifth layers address stresses in perpendicular directions. This localized quality approach ensures reinforcement is applied precisely where needed without creating abrupt transitions.

The reinforcing layer structure is designed to handle multiple types of loads simultaneously. The fiber layers are arranged to resist both radial stresses (from circumferential reinforcement) and flap-direction loads (from longitudinal fiber orientations). This multi-functional design ensures comprehensive protection against various loading conditions including fatigue damage from flap-direction forces.

The reinforcement transitions from two-dimensional circular-arc-shaped ribs to a three-dimensional laminated fiber structure. Multiple fiber layers are stacked with different orientations (0 degrees, 90 degrees, and intermediate angles) to create a volumetric reinforcement system that addresses loads from all directions, including the previously unprotected flap direction.