Explain the application of fiber optic sensors in structural health monitoring of WEC blades.

Fiber optic sensors are used in structural health monitoring (SHM) of Wave Energy Converter (WEC) blades to measure strain and temperature distribution along the blade's structure. These sensors are embedded within the composite material of the blade during manufacturing or bonded to the surface. Fiber optic sensors work by measuring changes in the properties of light as it travels through the optical fiber. When the blade experiences strain (stretching or compression) due to wave loading, the optical fiber is deformed, causing a change in the wavelength or intensity of the light passing through it. These changes are measured by an interrogator unit, which then calculates the strain at the location of the sensor. Similarly, changes in temperature also affect the properties of the light, allowing the sensors to measure temperature distribution along the blade. By strategically placing fiber optic sensors at critical locations on the blade, such as near the root or at points of high stress concentration, engineers can monitor the strain and temperature distribution in real time. This information can be used to detect damage, such as cracks or delaminations, to assess the overall structural integrity of the blade, and to optimize the WEC's operating parameters to reduce stress and extend the blade's lifespan. Distributed fiber optic sensors, which provide continuous measurements along the length of the fiber, are particularly useful for detecting localized damage.