PSI - Issue 28

Sahand P. Shamchi et al. / Procedia Structural Integrity 28 (2020) 1664–1672 Sah nd Shamc i et al. / Structu al Integrity Procedia 00 (2020) 000 – 000

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Table 1. Specimen geometry of each test typology. Specimen geometry Length [mm] Width [mm]

Thickness Reference (modified) [mm]

End-tabs (length × width × thickness) [mm 3 ]

Lay-up

Quasi-static Standard

110

10

1.47 (1.75)

50 × 10 × 1.5

[0] 16

Quasi-static non standard High strain rate

110

8

1.47 (1.75)

-

[0] 16

3. Experimental procedures 3.1. Quasi-static tests

Quasi-static experiments were carried out using a MTS 810 servo-hydraulic load frame with a load cell of 100 kN. Among them, 5 tests, per material configuration, were performed in accordance with the ISO 14126 standard [9] using the IITRI compression test fixture, which is referred to as “ standard compression” tests. The remaining quasi-static tests , labelled as “non - standard compression”, were carried out with the same test fixture employed in the split Hopkinson compression bar. The objective was to acquire an unbiased comparison between different loading rates. The test fixture is described in section 3.2. A crosshead speed of 1 mm/min was selected, for both test typologies, to obtain a strain rate value of 0.0016 s -1 . Two back-to-back strain gauges were bonded on the gauge section of the test samples to check the bending and buckling of the samples under compressive loading. In standard compression tests, the load was introduced via shear loading, therefore requiring the application of end-tabs to reinforce the test coupons as well as to reduce the local stress concentration. End-tabs were made of glass/epoxy composites with a length and thickness of 50 and 1.5 mm, respectively. A view of both standard and non-standard compression test setups is shown in Fig. 1.

(a) (b) Fig. 1. (a) Standard compression tests using IITRI test fixture, and (b) non-standard compression tests employing a fixture compatible with SHPB.