The sixth group of experiments was carried out from the 6th to the 8th of February 2023. Again, aluminium specimens with artificially created microstructure subjected to pure bending were examined. In this series of experiments, three specimens of the largest size (530×50,8×12,7 mm) with LMD microstructure were subjected to four-point bending.

Each of the specimens was loaded with three different support placements, differing in span, but always symmetrical. The experiments were performed on the ZwickRoell Z600 universal testing machine with a 50 kN load cell. As before, our area of interest was in the strains on the top and bottom of the specimens, the values of which were obtained via strain gauges. Additionally, LVDTs measuring vertical displacement were set up symmetrically to the vertical axis. The same values were also measured by means of DIC via the GOM Aramis software.

Analysis of a 3D printed samples (PLA) was performed in order to determine the modulus of elasticity and Poisson’s ratio. Dimensions of the samples are according to the norm ISO 3167 and they were printed with a 3D printer Prusa I3 MK3 owned by the Faculty. The first group of experiments consists of two types of samples, which differ in structure, i.e. in the direction of printing (0° and 45° in respect to the samples’ axis). The specimens were subjected to a tensile test in a Zwick 600 testing machine. Surface deformations were recorded with the GOM Aramis optical measurement system.

After determining the modulus of elasticity and Poisson’s ratio, prisms of identical material (microstructure corresponds to the previous samples) were 3D printed with dimensions 24x12x5 cm. A four-point bending test was performed on the Controls testing machine and the deformations and fractures occurring on the prisms were analysed in detail with the optical measurement system software.

This experiment is the part of the undergraduate thesis project of our student Antonio Milevoj under the supervision of Assistant Professor Edita Papa Dukić.

We want to capture a size effect phenomenon that manifests itself in increased stiffness of smaller specimens made of the same material (which is not recognized in the classical theory). For this reason we have a different size of aluminium specimens with artificially created micro-structure and in today’s experiment we have a smallest one. The dimensions of specimens are 150×12,7×12,7 mm and unfortunately this is too small for our Controls hydraulic testing machine. That is why this time we had an experiment in the Center for Micro- and Nanosciences and Technologies, Laboratory for Precision Engineering and Micro- and Nanosystems Technologies with the valuable help of doc. dr. sc. Ervin Kamenar.

Our 4^th group of experiments took place on 13^th and 14^thof July 2020. The aluminium specimens were subjected to a three-point bending on Shimadzu Autograph AGS-X testing machine (5 kN) using dedicated data processing software (TRAPEZIUM LITE X).

We monitored deformations at the specific points of the specimens via strain gauges and also, the experiments have been video recorded using specialised GOM Aramis software for strain measurement.

Our second group of experiments took place on 28^th of May 2020. Aluminium specimens were subjected to a four-point bending on Controls hydraulic testing machine. We had identical aluminium specimens as in the first group of experiments, but this time without artificially created micro-structure to obtain their Young’s modulus. This experiment is the part of the undergraduate thesis project of our student Damjan Jurković.

Our first group of experiments took place on 19^th and 20^th of December 2019. Aluminium specimens with artificially created micro-structure were exposed to four-point bending on the Controls hydraulic testing machine.

We monitored deformations at the specific points of the specimens via strain gauges and with the appropriate software programs.

At the same time, the experiments have been video recorded using specialised GOM Aramis software for strain measurement.