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SUMMARY:Uncovering fatigue damage development in unidirectional composites
  using x-ray computed tomography - Lars Mikkelsen\, Institute for Wind Ene
 rgy\, DTU\, Denmark 
DTSTART:20170217T140000Z
DTEND:20170217T150000Z
UID:TALK69642@talks.cam.ac.uk
CONTACT:Hilde Hambro
DESCRIPTION:Understanding fatigue damage evolution in the load carrying la
 minates of wind turbine blade play an important role designing longer and 
 lighter turbine blades. Turbine blades which will make it possible to incr
 ease the size of wind turbines or to upgrade existing turbines for lower w
 ind classes’. Thereby\, it will be possible to lower the cost of energy 
 for wind energy based electricity. In the presented work\, a lab-source x-
 ray computed tomography equipment (Zeiss Xradia 520 Versa) has been used i
 n connection with ex-situ fatigue testing of uni-directional composites in
  order to identify fibre failure during the fatigue loading. The load carr
 ying laminates in wind turbine blades is typically based on a number of no
 n-crimp fabrics in where the load carrying fibres are oriented in the axia
 l direction of the blades. In order to ease the handling of the fabric dur
 ing the dry fabric layup and to ensure a good alignment of the final lamin
 ates\, approximately 10% of the fibres are oriented in secondary direction
 s as so-called backing bundles and stitched to the uni-directionally orien
 ted bundles. Due to the coarse structure of the non-crimp fabric\, test sa
 mples with a larger cross-section (compared to other comparable x-ray stud
 ies) have been used in order to ensure a representative test volume during
  the ex-situ fatigue testing. Using the ability of the x-ray computed tomo
 graphy to zoom into regions of interest\, non-destructive\, the fatigue da
 mage evolution in a repeating ex-situ fatigue loaded test sample has be ex
 plored. Thereby\, the fatigue failure mechanism has been uncovered showing
  fibre breakage regions growing from cross-over regions of the backing bun
 dles. Based on those observations\, more realistic micromechanical based f
 atigue damage models as well as suggestions on bundle arrangement improvin
 g the fatigue resistance of non-crimp fabric used in the wind turbine indu
 stry can be made. 
LOCATION:Oatley Seminar Room\, Department of Engineering
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