Experimental/numerical study of anisotropic water diffusion in glass/epoxy composites

37th Risø International Symposium on Materials Science

Rocha, I.B.C.M.^1,2 ; Raijmaekers, S.^1 ; Nijssen, R.P.L.^1 ; Van Der Meer, F.P.^2 ; Sluys, L.J.^2

Knowledge Centre WMC, Kluisgat 5, Wieringerwerf

1771MV, Netherlands^1

Delft University of Technology, P.O. Box 5048, Delft

2600GA, Netherlands^2

关键词: Anisotropic Diffusion;    Concentration gradients;    Demineralised water;    Elevated temperature;    Geometric effects;    Glass/epoxy composite;    Unidirectional composites;    Wind turbine blades;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/139/1/012044/pdf
DOI  :  10.1088/1757-899X/139/1/012044

来源: IOP

【 摘 要 】

In this work a glass/epoxy composite commonly used in wind turbine blades is exposed to a humid environment at an elevated temperature. To research the anisotropic diffusion behaviour observed in unidirectional composite specimens, experimental results of slices cut along the three directional planes of the laminate immersed in demineralised water at 50° C are coupled with numerical modelling. The weight of the slices was measured at regular intervals, from which the uptake behaviour could be deduced. The process was modelled using a 3-dimensional RVE of the material, where diffusion is modelled as steady-state and the diffusivity in each direction was measured by applying concentration gradients to the model. The experimental data shows similar water uptake behaviour for samples in both transverse directions, while the water uptake in the fibre direction was significantly faster. A proper fit according to Fick's law was obtained for the transverse direction, while this was not possible for the samples in fibre direction, suggesting a strong dependency of the diffusion behaviour on the fibre orientation. Results from the proposed numerical models show that the geometric effect of fibres acting as barriers for the water movement is indeed responsible for part of the observed anisotropy.