PSI - Issue 73

Marie Horňáková et al. / Procedia Structural Integrity 73 (2025) 33 – 37 Marie Horňáková, David Juračka, Pavel Dobeš, Petr Lehner / Structural Integrity Procedia 00 (2025) 000–000

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3. Test setup and materials The electromechanical testing machine Labtest 6.1200 was used for the experiments. It was a classical compressive load test scheme (see Figure 1) in which displacement and force in the machine head were recorded. As noted above, five different samples were tested, all of which maintained the same test scheme, namely a gradual increment of displacement at a rate of 0.8 mm/second. The force-displacement curve recordings could then be compared for all tested samples. PC blend filament (polycarbonate) was selected to produce 3D printed samples. For each sample, a full straight filler with uniform filament direction was chosen according to the set with filament sizes of 0.4 mm to 0.2 mm. According to the printer manufacturer, the properties of the printed material are as follo ws: density = 1220 kg /m 3 , modulus of elasticity = 1.90 GPa, Poisson ratio = 0.35. The basic material used was wood in the form of prisms with a cross section of 50 x 50 mm, wood class C24 according to ČSN EN 338. Material properties: density = 380 kg/m 3 , modulus of elasticity in the X direction = 9.20 GPa, in the Y direction = 0.74 GPa, in the Z direction = 0.40 GPa, Poisson's ratio in the X direction = 0.47, in the Y direction = 0.25, in the Z direction = 0.37. In addition, shear pins were used, which were considered in steel grade S235. This material has the following properties: density = 7850 kg/m 3 , modulus of elasticity = 210 GPa, Poisson's ratio = 0.30. 4. Results The force-displacement diagram of all five tests was the basic source of results for the subsequent evaluation and comparison of the behaviour of the different joint geometries (see Fig.4). Since all samples were printed using the same technology with the same setup, and the only difference was the location of the pin holes, it was possible to compare the diagrams with each other and evaluate the effect of the hole locations.

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Fig. 4. Compression test results - force-displacement diagram.

The worst performance was shown by variant V02, which has three holes on the same side in one line parallel to the loading. This geometry design created high stress at the level of the same row of wood fibers of the wooden prism, which caused the wood to crack. The very similar geometry of variant V05 had the pins outside the same level, which