Bending moment matching method for single point fatigue loading test of wind turbine blades

Abstract

The invention belongs to a single-point fatigue loading test system for fan blades, and specifically relates to a bending moment matching method for a single-point fatigue loading test of wind power blades. According to the principle of equivalent substitution, the blades are discretely divided into n discrete parts along the wing direction, and the actual total bending is established. In the moment value model, combined with the principle of dichotomy, starting from the tip of the blade, for a certain section, the minimum value of the difference between the theoretical bending moment value and the actual total bending moment value is used as the objective function, and the errors of other sections are used as inequality constraints. An optimal solution algorithm based on the objective function and constraints is designed, and the number, quality and position of added counterweights are optimized by establishing a mathematical model and the number of added counterweights is guaranteed to be the least. Through the present invention, the actual test bending moment of the blade can be matched with the theoretical bending moment as much as possible under the premise of adding the least number of counterweights, and the accuracy of the fatigue loading test of the blade can be improved, and the accuracy can strictly meet the δ required by the industry (currently Usually 7%) error requirements.

Description

technical field [0001] The invention relates to a bending moment matching method for a single-point fatigue loading test of a wind power blade, which is especially suitable for a fatigue loading test of a megawatt-level wind power blade, and belongs to a single-point fatigue loading test system for a wind power blade. Background technique [0002] At present, the single-point fatigue loading test method is one of the mainstream methods for fatigue testing of wind turbine blades in the world. The single-point fatigue loading test method usually applies a single-point excitation to about 70% of the blade wing to make it resonate with the blade to complete the fatigue test. According to the IEC 61400-23 Full-Scale Structural Testing of Wind Turbine Blade standard, the actual bending moment of each end section of the blade caused by the single-point excitation should match the theoretical bending moment provided by the blade designer as much as possible. At home and abroad, mul...

AI Technical Summary

Problems solved by technology

However, due to the lack of an effective bending moment matching method, most blade testing manufacturers only add a counterweight at a suitable position in the blade wing direction to achieve the matching of the actual bending moment and the theoretical bending moment through experience or simple calculation, and the matching error is relatively large. , the relative error of some sections is far more than 7%, the resulting fatigue test data accuracy is not high, to a certain extent caused the distortion of the test results of the single-point fatigue loading test, it is difficult to meet the high-precision blade fatigue test requirements

Or as in Zhang Lei'an's paper "Research on Key Technologies of MW-level Wind Turbine Blade Loading System." Although the bending moment calculation model is given, the model is too simple and the subsequent optimization steps are vague, and no specific implementation method is given. The obtained bending moment distribution data cannot be verified by later generations, and the reliability is not high

According to the data provided by a certain blade manufacturer: Although a certain type of blade with a design service life of 20 years has passed the single-point fatigue loading test, its actual life is far below the design life

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