Numerical simulation of progressive damage in composite wind turbine blade under aerodynamic loads

The large size composite wind turbine blades for higher power output are subjected to extreme aerodynamic loads such as wind gusts during service life of 20 years. The loading conditions can induce large deformation and high stresses leading to progressive adhesive debonding between spar and skin and damage of composite skin; thus challenging structural integrity of the blade. These interactive damage modes of interface and skin are simulated by carrying out finite element (FE) analysis with Ansys software. In the FE analysis, cohesive zone model (CZM) using bilinear type law of traction-separation is employed to model adhesive debonding between spar and skin. Continuum damage mechanics (CDM) based approach is used for progressive damage analysis of the composite skin. Both these techniques are described by user through material subroutines. The simulation results indicated that high compressive stresses caused buckling of skin locally leading to debonding of adhesive interface between skin and spar on the suction side of the blade with subsequent progressive damage of the composite skin. Resultantly, the eventual load carrying-ability of the blade is dictated by coupling of adhesive debonding at the interface and skin failure. The simulation procedure implemented in this work can be used for development of reliable and economical computational models for investigating coupled damage modes and predicting failure response of the blade than costly experimental qualification testing.