PSI - Issue 42

Martina Drdlová et al. / Procedia Structural Integrity 42 (2022) 1382–1390 Martina Drdlova/ Structural Integrity Procedia 00 (2022) 000 – 000

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Prepared samples were tested at quasistatic and impact load. Quasistatic loading has been performed at 3-point bending. The tests were carried out using FORMTEST press machine with a range of up to 400 kN at a loading rate of 0.5 kN/s. The output of the measurements were stress/deformation curves and the ultimate strength at failure. Additionally, the bulk density of the individual test samples was also determined.

Fig. 1 Pendulum hammer KYV-1-2020 for impact testing of large-scale samples (left), samples for testing (middle) and preparation of test samples with polyurea coating (right)

The impact tests were carried out on the impact hammer pendulum KYV-I-2020, operating on Charpy hammer principle, see Fig. 1. The device is robust, the testing range is up to 1100 J, which allows testing of large-scale samples, representing better the real structures. The quantitative result of the impact tests is fracture energy, which can be used to calculate the impact toughness of the material according to the following formula: = ⋅ × 10 3 (1) Where: E i – energy required for breaking the test sample (J), H – thickness of the test sample (mm), b – width of the test sample (mm) Additionally, fragmentation was observed and quantified where relevant. Each test has also been recorded with Nicon J5 camera at 7200 fps speed to evaluate the failure mode. 3. Results and discussion Results from quasistatic loading in three-point bending are summarized in Table 2 and Fig. 2, The depicted graphs show the stress-deformation dependencies of the test samples. The graphs show significant differences in the load bearing capacity of the individual specimens, as well as significantly different behaviour of the individual variants after reaching the ultimate limit. From the total area under the strain curve, it is possible to predict the amount of energy that each material is able to absorb when loaded.