Characterisation of fatigue damage in a thick adhesive joint based on changes in material damping

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The adhesively-bonded connections in a wind turbine blade, e.g. the spar cap to shear web joins, are key elements for the structural integrity of the blade. These joins can suffer from damage at the bond-line which can propagate through the structure and compromise the operation of the blade. In this paper, we determine the damping properties of a test specimen representative of that joining a spar cap and a shear web during a period of progressive damage. In addition to the experimental damping measurement, an analytical dynamic model based on the visco-elastic properties of the material is developed to relate the damping to the loss factor. The experimental results show that when a crack is initiated in the test specimen, the damping increases by around 5-7%. This value increases with the propagation of transverse cracks in the adhesive and reaches a value of 35% when the adhesive layer experiences crack saturation and the damping reaches 45 % before failure occurs. Although a significant change in the damping is observed, there is no significant change in the natural frequency (<1%) and by association little change in the stiffness of the test specimen.

Original languageEnglish
Article number022058
Number of pages11
JournalJournal of Physics: Conference Series
Issue number2
Publication statusPublished - 22 Sep 2020
EventScience of Making Torque from Wind 2020, TORQUE 2020 - Online, Virtual, Online, Netherlands
Duration: 28 Sep 20202 Oct 2020

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