Progressive Damage in thin 2D Woven CFRP Laminates due to Stress Concentrations at Free Edges and Notches

  • Heinzlmeier, Lukas (Johannes Kepler University Linz)
  • Sieberer, Stefan (Johannes Kepler University Linz)
  • Wolfsgruber, Thomas (Johannes Kepler University Linz)
  • Kralovec, Christoph (Johannes Kepler University Linz)
  • Schagerl, Martin (Johannes Kepler University Linz)

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In the present paper the relevant literature regarding progressive damage in thin-walled 2D-woven CFRP laminates due to stress concentrations at free edges and at notches are reviewed. Starting with free edge effects laminates comprising uniaxial layers of fibres, the effects on static and fatigue characteristics are summarised. Special focus is given to the small body of literature on free-edge effect in woven fabric laminates. In the context of stress concentrations at notches, explicit emphasis is placed on those induced by circular holes, as these are commonly used to join structural components by bolts, as well as to pass hydraulic and electrical lines though them. This paper furthermore outlines a potential testing set-up to alleviate the effect of the free-edge effect originating from the external straight edge on narrow coupon specimens from the effect of the hole on fatigue in plain-woven CFRP laminates. A different specimen design is required, as the outer free edges and the hole are interacting. This mutual influence, due to the small dimensions (sample width in relation to hole size), has been observed earlier and emphasizes the importance of having a different specimen. One possibility is to use wider plate specimens rather than conventional coupons. These specimens enable not only to observe the onset of damage but also the damage progression unaffected by the free edge for a longer cycle time.