Application of Structural Similitude Theory in Subcomponent Testing of Wind Turbine Blades

摘要

Currently material selection for wind turbine blades is based upon initial couponrntesting to evaluate mechanical properties (e.g. stiffness, delamination strength, fatiguerndurability) and also full-scale tests to benchmark the final design. However, therncoupon testing is often not representative of the mechanical performance in full-scalernblades, so time-consuming and very expensive full-scale tests are required to quantifyrnthe blade durability. Appropriate sub-component testing has the potential to bridge therngap between coupon and full-scale tests and to expedite the material characterizationrnand structural optimization saving both time and money. In this study, the similarityrnconditions of an analytical model of a simply-supported plate analogous to the sparrncap of a wind turbine blade are investigated with the objective of designing anrnapplicable scaled down subcomponent. Based on direct use of the governingrnequations, bending of a specially orthotropic rectangular laminated plate underrntransverse loads is analyzed to extract the scaling laws. Theoretical maximumrndeflection of the subcomponent is mapped to the deflection of spar cap using scalingrnlaws. Accuracy of the scaling laws in mapping the data is then used as arnsubcomponent design criteria and the effect of the ply stack up scheme and size ofrnsubcomponent are investigated by applying complete and partial similarity conditions.rnThe results indicate that subcomponents with distortion in ply stack up can predict thernmaximum deflection of the prototype with good accuracy. However, usingrnsubcomponents with different aspect ratios than the prototype yield an inaccuraternprediction of prototype response.