PSI - Issue 51

Hugo Vidinha et al. / Procedia Structural Integrity 51 (2023) 9–16

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H. Vidinha et al./ Structural Integrity Procedia 00 (2022) 000–000

Fig. 3. Inter fiber fracture (IFF) pattern progression for four loads at three plies with different fibre orientations (relative the force direction represented by the green arrows).

Fig. 4. Fibre fracture (FF) pattern progression for four loads at three plies with different fibre orientations (relative to the force direction represented by the green arrows).

direction is represented in both figures by the green arrows. When we compare these two previous figures, it is clear that the failure region induced by IFF is much wider than that induced by FF. Furthermore, the plies featuring greater fibre damage display the lower matrix damage and vice-versa. The matrix damage emerges at earlier load stages when compared to the fibre damage, as expected. In plies where the fibre is oriented in the same direction as the load, most of the load is carried out by the fibres, resulting in higher fibre damage. Consequently, little matrix damage develops in those plies as can be verified in ply 5 of Fig. 3. If the fibres are oriented at 45º relative to the force direction, less load is carried by the fibres when compared to the former case and thus, less fibre damage and greater matrix damage are verified in those plies. Lastly, if the fibres are oriented perpendicularly to the force direction, all the load is carried by the matrix resulting in enormous matrix damage and no fibre damage. Another interesting aspect is the variation of strain levels in the different laminae of the tested specimen. Fig. 5 compares the linear strain ε �� of the 12 plies situated in the same z-axis position (the z-axis direction refers to the