In this article, an energy-based model for predicting fatigue life and evaluation of progressive damage in a full composite wind turbine blade is proposed. It is based on the assumption that the damage growth rate in a composite material depends on the maximum value of elastic strain energy per cycle. Design, finite element modeling, and dynamic analysis of the blade have been performed using ANSYS software. The first five natural frequencies and mode shapes of the blade were calculated and dangerous nodes in the critical location were determined using the modal and harmonic analysis techniques. Obtaining critical stresses from ANSYS analysis, fatigue life of the blade at the first natural resonance frequency was estimated by the model. Results showed that the calculated life of the analyzed blade could meet the design requirement.

In this paper an energy-based model for predicting fatigue life and evaluation of progressive damage using plane-stress assumption is proposed. This model allows us to predict fatigue durability taking into account principal directions of the stress tensor relative to planes of elastic symmetry of material. First, the unknown parameters of this model will be calculated for three different composites with various lays-up. Method for determining these parameters is based on the minimum necessary set of experimental data. Afterwards the model was used to predict fatigue life and estimate accumulated fatigue damage in a unidirectional composite under different angles of loading. The analysis of conclusions of the theory for various loading conditions was carried out and performed comparison between the experimental data and predicted results. The predicted fatigue lives obtained by the proposed energy model were in good agreement with the experimental data.

In this paper an energy-based model for predicting fatigue life and evaluation of progressive damage in composite materials is proposed. The damage model is based on the concepts of continuum damage mechanics. The applicability of the proposed energy model was studied in fatigue experiments on 10-layer composite laminates made of glass fabric impregnated with epoxy-phenolic resin. Experimental results were processed by the method of least squares to determine the unknown parameters of the model. Theoretical fatigue strength curves are in good agreement with experimental data.