PSI - Issue 64

Amrita Milling et al. / Procedia Structural Integrity 64 (2024) 1009–1016 Milling/ Structural Integrity Procedia 00 (2024) 000 – 000

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by a factor of 1.1 to 1.9. Generally, the tensile parameters increased with increasing strain rates. However, ANOVA analysis suggested no statistical correlation between strain rate and the tensile parameters due to the large scatter in the data.

a

b

c

Fig.4. Dynamic increase factors (a) tensile strength, (b) ultimate strain, (c) toughness.

3.3. Effect of Strain Rate on Crack Propagation and Failure The stress that initiated the first crack in the matrix tended to increase as the strain rate increased, with the exception of the specimens in the range of 0.59 and 0.95/s. It is suspected that these samples may have been affected by flaws in the specimen production process. Fig.6 shows the crack patterns of one representative sample from each range of strain rates at the point of failure. Multiple successive cracking can be seen in the quasi-static and dynamic specimens, indicating that the reinforcement (grid and short fibres) embedded within the matrix were effectively bridging the cracks (Fig.6a). The number of cracks and their locations in the region of interest were highly variable for each strain rate range. In general, larger crack width openings at the point of failure were observed for the dynamic specimens.

QS-0.0069/s

D-0.95/s

D-2.41/s

D-6.17/s

Fig.5. Crack patterns of specimens at the point of fracture.