Comprehensive computational framework for structural test simulations of wind turbine blades

Wind turbine blades have grown significantly in size, with current blades reaching up to 130 m, driven by the increasing demand for renewable energy. These large blades must undergo an extensive certification process that involves rigorous and time-consuming structural testing to ensure their performance and safety in compliance with established certification standards. The key standards for wind turbine blades include IEC 61400-23 [1] and DNV-ST-0376 [2], which define the testing protocols for assessing blade properties, static strength, fatigue, and damage tolerance. Testing of large wind turbine blades poses significant challenges in terms of time and resources for structural assessments. Full-scale testing for blades over 100 m in length can take several months to a year. Their massive size and weight necessitate specialized equipment, and tests like static and fatigue require substantial time for setup, execution, and analysis. The duration of testing is a key concern for manufacturers and certifying agencies, following established uniaxial testing procedures in the flap and lead-lag directions, with recent developments in biaxial methods for reduced testing times [3, 4].
Owing to the need for highly efficient simulations to explore a multitude of test setup scenarios, most of the previous studies relied on simplified beam-based structural models considering only the bending loads while neglecting the effects of torsional, shear, and extensional loads that may be induced due to the presence of elastic couplings (e.g., bend-twist coupling) in blades. There is a need for a systematic test design simulation process that includes not only fatigue tests but also static and modal tests, which has not been attempted comprehensively in the literature. To this end, this study proposes a general modular framework, called Blade-INT, for test simulations while allowing the incorporation of moderate-fidelity structural models with an arbitrary definition of a blade reference line that includes the effects of fully coupled stiffnesses through a generalized Timoshenko-like beam element. It should be remarked that due to the modular nature of the present framework, complex models for aerodynamic and fatigue calculations can be easily integrated into the overall methodology