PSI - Issue 56

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Author name / Structural Integrity Procedia 00 (2019) 000–000

Laszlo Racz et al. / Procedia Structural Integrity 56 (2024) 3–10

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Fig. 1. Investigated infill patterns.

Test specimens made of acrylonitrile butadiene styrene ABS (Plasty Mladeč, Czech Republic) were manufactured horizontally on the build-plate of the 3D printer (Wanhao Duplicator I3) controlled by Simplify 3D software. Directions 0° and 90° are considered along and perpendicular to the longitudinal symmetry axis of the specimen, all layers of a specimen were built in the x-y plane (x, y and z axes defined according to ISO/ASTM 52900:2015). The specimens were manufactured by first building a parametric wall, called shell, that is created by the printer to reach the required dimensional precision and to create the inner pattern. The meso-structure of the printed specimen’s cross section was analyzed under a microscope to establish the real shape and structural interaction of the fibers. The structure of the fibers in the cross-section from the numerical model was compared to the detailed pictures of the printed specimens. It can be noticed that the extruded filament is in a semi-molten state, and it would flatten slightly when deposited onto the previous layer as indicated in Fig. 2.a.

Fig.2. Determination of the contact area between the filaments a) inter layer and intra layer necking, b) optical measurement.

This flattening effect leads to the formation of a larger contact area between the filaments, known as intra and inter layer necking as presented in Fig. 2a. To determine the real size of the contact area between the layers, marked with lighter lines (Fig. 2b), microscopic pictures were analyzed with Digimizer software (MedCalc Software Ltd,