PSI - Issue 47

Aghiles Khris et al. / Procedia Structural Integrity 47 (2023) 888–891 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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For each pressure used, two spring positions were used: 4 springs positioned in the middle of the preform (noted + springs) and 8 springs all around the preform . Finally, the fabric was oriented at 22.5° with respect to the main axis of the tool then at 45°. and at least two tests have been performed for each configuration 3. Results and discussion In this work, we were interested to the slippage defects which appear in the triple points of the perform (Fig. 3a), the sliding defects observed on the faces of the perform (Fig. 3b) and the shear between the two warps of roving.

Slippage Sliding

Fig. 3. Defects appearing in the configuration 4R. Fabric oriented with: (a) 22.5°; (b) 45°.

Fig 4. shows the measured slippage pour the three pressures, the two configuration (4R and 8R) and the two orientation of the fabric: 22.5° and 45°. We observe that the slippage is more important in the case of a 22.5° orientation of the fabric, confirming the importance of the fabric position on the preform quality. The slippage intensity increases proportionally with the pressure. For both fabric orientations, the slippage defects are lower in the case of the 4R configuration. This can be associated to the fact that the location of springs in the corners (for 8R) increases the defects

Fig. 4. Slippage measured on the fabric oriented with: (a) 22.5° ; (b) 45°.

Fig 5. shows the variation of the sliding versus the applied pressure for the two configurations of springs (4R and 8R) and the two orientation of the fabric: 22.5° and 45°. We observe also the dependence of the intensity of the sliding on the applied pressure. However, the tendency is not very clear. This can be related to the fact that the sliding is a mesoscopic defect, so it ’ s sensitive to the variability of local conditions (stress, friction …). We also notice for medium and high pressures that the sliding is lower for the fabric oriented at 45°.