The present study provides a thorough analysis of the influence of filament orientation on the tensile stiffness of 3D-printed structures. This exploration employs a combination of numerical simulations and experimental trials, providing an extensive understanding of additive manufacturing, particularly 3D printing. This process involves layer-by-layer material deposition to produce three-dimensional objects. The examination specifically targets PLA-based 3D printed structures created using Fused Filament Fabrication (FFF) technology and subjects them to rigorous evaluations using a universal tensile testing machine. Additionally, this approach combines Representative Volume Element (RVE) and Classical Lamination Theory (CLT) techniques to extrapolate the mechanical properties of the test material. Although the initial methodology faces challenges in determining the shear modulus with precision, an in-depth investigation results in enhanced accuracy. Furthermore, this study introduces a parametric RVE numerical method, demonstrating its resilience in handling sensitivity to shear modulus. A comparative study of results derived from both the analytical methods and experimental trials involving five series of samples with varied layups reveals that the newly proposed numerical method shows a stronger correlation with the experimental outcomes, delivering a relative error margin of up to 8%.

The paper deals with the design of the stacking sequence of layers in the laminate beams with open-cross sections in order to create the desired behavior in the post-buckling range. Laminate beams with channel and lipped channel cross-sections made of glass fiber reinforced polymer (GFRP) laminate with different layer arrangements (symmetrical and nonsymmetrical) have been considered. In case of the nonsymmetrical stacking sequences, hygro-thermally curvature stable (HTCS) laminates have been taken into account. Pure bending was assumed as the type of load. In the case of beams with open cross-sections, this load type can cause the lateral-distortional buckling mode. A parametric study was performed to analyze the influence of layer arrangement on post-buckling behavior. The finite element method was used to developed numerical models and conduct simulations. Additionally, the experimental tests of the channel section beams were performed in order to validate the developed numerical models.

The interactive buckling phenomenon in thin-walled channel section beams is investigated in this paper. This study deals with medium length beams made of the step-variable functionally graded materials (FGM) which consists of aluminum and titanium layers. The interaction of local, primary and secondary global buckling mode and their effect on the load-carrying capacity is discussed. The parametric studies are performed to assess the effect of the thickness of the beam’s component, its length and position of the individual layer on the equilibrium paths. Additionally, the influence of the adhesive layer between materials was analyzed. The problem was solved using the Finite Element Method.

The presented study is focused on the modification of commercially available epoxy resin with flame retardants by means of using natural substances, including quercetin hydrate and potato starch. The main aim was to obtain environmentally friendly material dedicated to rail transport that is resistant to the aging process during exploitation but also more prone to biodegradation in environmental conditions after usage. Starch is a natural biopolymer that can be applied as a pro-ecological filler, which may contribute to degradation in environmental conditions, while quercetin hydrate is able to prevent a composite from premature degradation during exploitation. To determine the aging resistance of the prepared materials, the measurements of hardness, color, mechanical properties and surface free energy were performed before and after solar aging. To assess the mechanical properties of the composite material, one-directional tensile tests were performed for three directions (0, 90, 45 degrees referred to the plate edges). Moreover, the FT-IR spectra of pristine and aged materials were obtained to observe the changes in chemical structure. Furthermore, thermogravimetric analysis was conducted to achieve information about the impact of natural substances on the thermal resistance of the achieved composites.

The aim of this research was to explore the innovative use of natural additives, containing phytochemicals with proven antimicrobial effects, in the production of epoxy–glass composites. This study was based on information regarding the antimicrobial effects of phytochemicals present in Cistus incanus, Zingiber officinale, and Armoracia rusticana. The additives were subjected to a gas chromatography (GC) analysis to determine their composition, and, subsequently, they were used to prepare resin mixtures and to produce epoxy–glass composites. Samples of the modified materials were tested against E. coli, S. aureus, and C. albicans. In addition, flammability and durability tests were also performed. It was found that the strongest biocidal properties were demonstrated by the material with the addition of cistus, which caused a reduction of microorganisms by 2.13 log units (S. aureus), 1.51 log units (E. coli), and 0.81 log units (C. albicans). The same material also achieved the most favorable results of strength tests, with the values of flexural strength and tensile strength reaching 390 MPa and 280 MPa, respectively. Public transport is a place particularly exposed to various types of pathogens. Currently, there are no solutions on the railway market that involve the use of composites modified in this respect.