A physics-based multi-scale progressive damage model was developed for predicting the durability of
wind turbine blade structures. Computational micromechanics was coupled within a continuum damage
mechanics (CDM) framework, and implemented through a user-defined subroutine within commercial
finite element software, for evaluating sub-critical damage evolution and stiffness degradation of the
blade structure. The study is the first step in developing an accurate prediction model for composite wind
turbines that accounts for the multi-scale nature of damage in rotor blades. The quasi-static and fatigue
simulation results demonstrate the ability of the model to predict the evolution of damage in the critical
regions of the blade structure, which is an important contribution and essential for increasing the accuracy
of damage tolerance analyses and for certification of composite structures. A parametric study of
blade geometric parameters also revealed a correlation with damage evolution, providing valuable
insight for optimization of blade designs.