DISTRIBUTED CURE MONITORING FOR WIND TURBINE BLADES

Distributed dielectric cure monitoring allows the measurement of composite cure state at many locations in very large structures such as wind turbine blades and composite beams. Distributed dielectric cure monitoring also avoids the tangle of extension cables used for monitoring parts requiring multiple sensors, such as aircraft and spacecraft components.

Dielectric cure monitoring uses the same sensors and measurements for research, quality control and manufacturing applications. Dielectric Analysis (DEA) correlates with laboratory tests such as differential scanning calorimetry (DSC) or dynamic mechanical analysis (DMA). As a result, DEA can act as the “go between” that brings information about composite cure from the research lab to the manufacturing floor, and from the manufacturing floor to the manager responsible for product quality.

Dielectric cure monitoring can immediately improve productivity for high value items like wind turbine blades. These blades, often more than 50 meters long, are fabricated in a mold. The thickness of the blade and the exotherm during processing vary along its length. Consequently, the rate of cure also varies along its length, and manufacturers must use experience and guesswork to determine the optimum demold time. Removing a blade too soon can cause cracks because it is not stiff enough, and removing a blade later than necessary reduces throughput.

Dielectric sensors installed in the mold at strategic locations, or perhaps every five meters along its length, for example, can determine when composite cure along the entire part has reached a desired point. Only at that time would the wind turbine blade be removed from its mold. As a benefit, if a factory ships even as little as one or two more blades a week, profitability increases.