PSI - Issue 24

9

Dario Fiumarella et al. / Procedia Structural Integrity 24 (2019) 11–27 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The top edge of the zone A is fixed to the clamping devices and if the yarns are inextensible, no shear deformation is induced in the region A during the test. The zone C in subjected to pure shear and it behaves as a trellis mechanism. The shear-deformation in the zone B is assumed to be half than the one in the region C (Taha at al. 2012). The Figure 7 shows a sequence of the specimen subjected to the bias-extension test. The zones A, B and C are clearly noticeable.

Figure 7: Sequence of stages during the bias extension test.

Figure 7A shows the undeformed specimen. As soon as the load was applied, the yarn re-orientation started in the central zone (Figure 7B). After the first stage, the compaction of the tapes caused the shear-locking (Figure 7C). At this point, an out-of-plane deformation can be noticed in the central zone. In the last stage (Figure 7D), the wrinkling of the tape occurred, and the load sharply increased.

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Figure 8: Force-Stroke trend of the bias-extension test performed on the PURE © fabric