Digital image correlation and acoustic emission for damage analysis during tensile loading of open-hole flax laminates.

• The effect of open-hole on mechanical properties of flax laminates was investigated. • Strain field around hole was analysed using Digital image correlation. • Acoustic emission was used to monitor the progressive damage during tensile testing. • Acoustic events were classified to calculate the contribution of each damage modes. • SEM pictures were used to visually identify the damage mechanisms. The present paper is dedicated to the assessment of the damage taking place in open-hole flax bio-epoxy laminates with different stacking sequences. Tensile test results have shown significant effects of the open hole on the performance of the laminate. Moreover, strain maps have allowed to detect the onset of cracks and to discuss their contribution to the laminates failure. For unidirectional laminate, splitting was observed as the main damage at the hole boundary along the fiber orientation and parallel to the loading axis. However, the [0 90] 6s laminate failure has caused by the onset of subsurface cracks in the 90° plies. Even if the tensile strength was decreased, the strain fields result has shown a less hole sensitive behavior of the [0 +45 90 −45] 3s laminate. Finally, damage monitoring using acoustic emission has shown a significant increase of the fiber-matrix debonding and fiber breakage contribution to the laminate failure. [ABSTRACT FROM AUTHOR]