PSI - Issue 51

Maja Dundović et al. / Procedia Structural Integrity 51 (2023) 192 – 198 M. Dundovi ć et al. / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 2. (a) Flexural tests sample; (b) Corner-filleted flexure hinge sample; (c) Experimental set up.

First sample, denoted as Sample A, has been tested with a displacement from -2 to -4 mm, while second sample, denoted as Sample B, has been tested with a displacement from -2 to -5 mm. The tests have been conducted using the STEP Lab’s dynamic testing machine in environmental conditions of 23 ± 2 °C temperature and 50 ± 5 % relative humidity. Load data has been measured with the 100 N capacity load cell, the motor encoder (used to derive relative motion of the loading nose), and the digital microscope (used for horizontal displacement measurement). The testing

set up is shown in Fig. 2c. 3. Results and discussion 3.1. Flexural tests

Three-point flexural tests have been performed on the rectangular beam samples printed in vertical and horizontal orientation, in three repetitions each, and the most representative samples are shown in Fig. 3 forming the stress-strain curves. Note that the toe compensation has been performed in accordance to ASTM D 790 standard’s Annex A1. Significantly different material properties for the two orientations have been obtained; horizontally printed samples exhibited brittle behavior, as shown in Fig. 3b, while the vertically printed samples yielded and consequently have a higher deformation, as shown in Fig. 3a. The flexural moduli have been calculated using a linear regression: 1570 MPa and 950 MPa for vertically and horizontally printed samples, respectively.

Fig. 3. Flexural tests result for (a) vertically printed sample; (b) horizontally printed sample.

3.2. Corner-filleted flexure hinges experiments The material properties obtained from flexural tests on vertically printed beams have been used as an input data for the numerical analysis performed using ANSYS Workbench’s Static Structural analysis system. Material behavior has been simulated using multilinear isotropic hardening plasticity material model. Load has been introduced as a