As fundamental eco-friendly renewable energy sources, wind turbines are designed to operate over a lifespan of 20 years. Hence, long-term structural reliability of wind turbine components is critical especially when high cost of manufacturing, inspection and repair, especially for turbines located in remote regions is considered. Composite blades are among the main components of a wind turbine, which are subjected to complex loading conditions. Their long-term structural integrity can be achieved with an in-depth understanding of the failure mechanisms and/or modes that may lead to their ultimate breakdown.

In this regard, full-scale structural tests enable us to monitor mechanical response of blades under various loading conditions. Yet these tests must be accompanied with numerical simulations, so that the physical basis of the progressive damage development can be captured and understood correctly. Moreover, failure initiation and ultimate failure can be determined using progressive damage models prior to testing.

Within the scope of this work the previous work of the authors of this study concerning the strength analysis of an existing 5-meter GFRP turbine blade using Puck failure criteria is revisited. In the previous work the FE Model of the blade was built in ANSYS ACP environment. ANSYS APDL Code was developed to carry out progressive damage analysis and degradation rules. As a part of the previous study, linear Puck material model was compared with the nonlinear progressive Puck material model. It is seen from the results of the previous study that load patterns change as the elements fail when progressive Puck criteria are used. It is therefore concluded that progressive failure analysis is necessary to capture a more realistic simulation of failure mechanisms prior to testing.

In the first stage of this work, failure mechanisms which occur in the wind turbine blade aeroshell during virtual static flap-wise bending full-scale test are identified. In the second stage, physically based phenomenological fatigue damage analysis will be carried out to investigate the failure mechanisms in the blade aeroshell during flapwise cyclic loading. As an ultimate goal of the study damage development during static and cyclic loading conditions will be compared.