PSI - Issue 2_A

Tarpani J.R. et al. / Procedia Structural Integrity 2 (2016) 136–143 Tarpani et al. / Structural Integrity Procedia 00 (2016) 000–000

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projections of these two tomographic C sections as seen as bold white lines in Figure 5a (in this regard, Figures 5b,c correspond to, respectively, the outer and the inner positions in regard to Figure 5a). On the other hand, Figures 5d,e refer to another pair of distinct C section views located nearby the opposite side of the test coupon, so that the projections of these tomographic C sections are seen as dashed white lines in Figure 5a (in this sense, Figures 5d,e correspond to, respectively, outer and inner positions in regard to Figure 5a). It becomes clear that according to Figure 5b an extensive damage growth took place starting from the pre-notch tip and extending through about half the width of the test coupon, while Figure 5d shows that in the opposite side of the EPX-CF damage is practically absent. This unbalanced or disproportional damage growth in regard to the laminate thickness is corroborated by a more detailed examination of Figure 5a, where the region inside the solid white circle indicates large amount of water adhered to the created fracture surface of the specimen. However, this does not occur at all in the adjacent region contained inside the dashed white circle, thus indicating incipient local cracking and limited water entry to allow for unequivocal indication by NMR technique.

Width

Pre-notch

T h i c k n e s

Translaminar damage growth

Width

(d)

(b)

Pre-notch

(a)

(c)

(e)

Fig. 5. NMR images of the EPX-FC composite laminate with translaminar fracture, as obtained via FLASH-3D protocol: (a) Axial view; (b) and (c) Coronal views near to one of the lateral sides of the specimen showing extensive cracking starting from the pre-notch tip; (d) and (e) Coronal views adjacent to the opposite lateral side of the specimen displaying almost no damage growth from the pre-notch tip. From the cases analysed in this work, one can deduce that, in general, combining sagittal and coronal section views is suffice to fully characterize fracture damage in solid carbon fibre-reinforced polymer composite laminates devised to structural bioapplications. This approach reduces both the time and cost of patient examination, since the number of axial tomographic sections required to wholly characterize the damage-types studied here (particularly translaminar fracture) is much higher than that of either coronal or sagittal sections. However, in particular cases such as unbalanced translaminar cracks with respect to the test coupon thickness, axial tomographic section views will compete directly with the sagittal ones in acquiring important information to corroborate findings obtained via coronal views, hence rendering the checkup more costly and time consuming. 5. Conclusions i. The FLASH-2D protocol applied to axial section view enabled the best visualization of both the delamination fracture in PPS-CF laminate and the SBF trapped in that region. However, imaging-time was much longer as compared to the RARE-2D protocol, which still provided information with acceptable quality;