Methodology to Predict Stiffness Knock-down in Laminates for Wind Turbine Blades with Artificial Wrinkles
- 1Department of Wind Energy, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark
- 2Vestas Wind Systems, Hedeager 42, 8200 Aarhus , Denmark
- 1Department of Wind Energy, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark
- 2Vestas Wind Systems, Hedeager 42, 8200 Aarhus , Denmark
Abstract. This work presents a methodology to evaluate the effect of wrinkles defects in the stiffness response of laminates characteristic of wind turbine blades. The assessment is carried out through numerical models and experimental tests with coupon specimens embedded with artificial wrinkles. Specimens are manufactured with two types of defects, prone to arise along the manufacturing process of wind turbine blades. Image-based numerical models were built to enclose the actual features 5 of the cross-sectional wrinkling of each defect type. Experimental quasi-static tension and compression tests were performed, where extensometers collect the strain distribution about the wrinkle section as around the flat section of the test specimens. 2D finite element simulations carried out in Abaqus/Standard captured the stiffness behaviour of the two types of wrinkles. The numerical approach is validated against the quasi-static tests retrieving a fair agreement with experimental data. A significant knock-down in the stiffness response was found due to the wrinkle with larger aspect ratio amplitude/half-wavelength.
Heloisa Guedes Mendonça et al.
Status: open (extended)
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RC1: 'Comment on wes-2022-28', Anonymous Referee #1, 02 Jul 2022
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This work presents an experimental and numerical investigation into the stiffness knockdown of GFRP laminates with artificially manufactured embedded wrinkle defects. Overall, the paper is well written, easy to understand and contains valuable information. A few queries are as follows:
1) It appears that the experimental/computational excercise on stiffness evaluation is carried out at a stage when no global failure mode (such as delamination) has been triggred from the wrinkle. If so, can the authors please mention this fact clearly? This is important, since if the load level triggers damage, more pronounced difference in stiffness will be seen between the 'flat section' and 'wrinkle section'
2) The authors have mentioned that the simplified surrogate model eliminates minute geometric details of ply folds and resin pockets, while the high fidelity model captures all these details. It would be good to include images of meshed finite element models of surrogate vs high fidelity models side by side and also compare the total number of elements . Since , the results in Figure 9 indicate that the surrogate model predictions for both type of wrinkles are very close to high fidelity models, it would be interesting to know the simplified meshing pattern that still produces an accurate results. Also, can the authors compare the computational time saving while using the surrogate model vs the high fidelity model?
3) Although shear loading in the wrinkle section and associated hysteretic loss in the resin is experimentally measured, the model does not assume any hysteretic damping effect. Can the authors suggest how their experimental finding on hysteresis loss be included in a future model development?
Heloisa Guedes Mendonça et al.
Heloisa Guedes Mendonça et al.
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