Numerical Simulation of Lightning Strike Damage to Wind Turbine Blades and Validation against Conducted Current Test Data

This paper presents a novel numerical approach to simulate lightning strike damage to equipotential bonding interfaces of wind turbine blades, and model validation based on high-current testing. Modern rotor blades are equipped with metal receptors to intercept the lightning leader and metal down conductors to conduct the lightning current, preventing the direct attachment to the CFRP spars. In such conditions, damage in the form of resin thermal degradation and sparks develop inside the blade at the equipotential bonding interfaces. Excellent correlation was found between the numerical predictions and test results in terms of current and temperature distributions. High temperatures were predicted at the sparking areas observed in the tests, which suggested that the damage is thermally activated. Thermogravimetric analysis data indicated that the epoxy pyrolysis process evolves in stages, and that sparking events are often initiated by release of gases and formation of small voids at temperatures lower than expected