Quantitative analysis of the impact of wrinkle defects on the strength of wind turbine blade main spars

Abstract Understanding the impact of wrinkle defects on the main spar of wind turbine blades is crucial for maintaining structural integrity and ensuring operational efficiency. This paper focuses on a quantitative analysis to determine how varying severities of wrinkles affect the structural strength of wind turbine blades. First, the study employed infrared nondestructive testing technology to inspect in-service wind turbine blades, identifying wrinkle characteristics. Based on these detected characteristics, finite element models were established to simulate the structural behavior. The Hashin failure criterion was employed to forecast the initiation of intralaminar damage, while a cohesive model with a bilinear traction-separation criterion was used to evaluate the interlaminar stress state and damage behavior of the laminates. Last, to achieve accurate simulation, a VUMAT subroutine was developed and executed in the ABAQUS software environment. The simulation results for ultimate tensile strength at different ratios of amplitude to wavelength were found to be within 10% of the experimental values. This level of accuracy underscores the reliability of the models used. The study revealed that as the ratio of amplitude to wavelength increases from 0.4 to 0.69, the ultimate tensile strength of the laminate structure decreases to one-fourth of its original value. This significant reduction highlights the severe impact that wrinkle defects can have on structural performance.