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Title:
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The effect of moisture on the fatigue performance of glass fibre reinforcedpolyester coupons and bolted joints
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Author(s):
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Published by:
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Publication date:
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ECN
ECN
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1996
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ECN report number:
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Document type:
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ECN-C--96-015
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ECN publication
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Number of pages:
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Full text:
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34
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Download PDF
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Abstract:
Although generally glass fibre reinforced plastics (GFRP) are found tohave good weathering properties, the effects of moisture on the fatigue
properties are not negligible. In order to investigate the influence of
moisture, fatigue tests were performed on preconditioned GFRP coupons and
bolted joints. The results are compared to dry GFRP coupons and bolted joints
from a previous fatigue study. The investigation on the preconditioned
coupons shows that testing in a wet environment reduces the lifetime
significantly. Testing under wet and hot conditions even reduces the lifetime
by about 2 decades. However, after testing in the dry lab environment there
is hardly any difference in fatigue lifetime between the normal and
preconditioned specimens. Neither variants of the ENWISPER preconditioned
coupon tests showed a degradation in lifetime compared to the reference set.
For the bolted joints, there is only a small reduction in lifetime caused by
the ENWISPER preconditioning. From the results it can be concluded that
moisture significantly affects the fatigue lifetime during testing and that
the influence of preconditioning is negligible. The combination of moisture
and fatigue loading can be a critical condition for a wind turbine blade,
especially on locations where the GFRP is not coated. Therefore an increased
fatigue damage by more than one order of magnitude can be expected during the
time moisture is condensed inside the blade. 7 figs., 8 tabs., 13 refs.
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