Investigating the Application of Guided Wave Propagation for Ice Detection on Composite Materials

Wind turbines operating in cold regions face icing problems. At the same time these regions are one of the best places to install the wind turbines. To minimize this problem and optimize the de-icing system it is very important to have an efficient ice detection system. Application of guided wave propagation has been previously considered in aircraft industries. To study this application for wind turbines, guided wave propagation should be investigated in composite materials. In the current work, first the guided wave propagation in multi-layered anisotropic materials is mathematically modelled and dispersion curves were obtained. Moreover the composite plate was homogenized to an anisotropic plate in order to simplify the calculations. Comparison of dispersion curves shows changes in group velocity when a second layer as ice is added on top of the first layer. Next, a finite element model was made to observe the effects of ice accretion on top of a composite plate. An experimental set-up was also developed at a cold climate lab on a composite test object used in wind turbine industry. The guided wave propagation was studied experimentally to see the effect of temperature and ice on the material and measurement data was obtained to validate the computational model. Both numerical and experimental results show that a patch of ice on top of a composite plate reflects the propagated guided waves with an amplitude that raises by increasing the thickness of the ice layer. Furthermore, ice accumulation affects the group velocity of the guided waves and it proves that the use of guided waves is a promising method to detect ice on turbine blades.