Additive manufacturing (AM), especially vat photopolymerization processes such as digital light processing (DLP), enables the production of highly detailed and complex geometries with precise material structure control. In this study, the influence of internal structure on the mechanical properties of PLA resin specimens produced using a DLP 3D printer is investigated. Two designs were analyzed: a fully solid structure and a shell with a Voronoi pattern. Tensile and bending tests revealed that solid specimens exhibited higher strength, while Voronoi structures performed better under bending loading despite lower load-bearing capacity due to their porosity ratio. The developed numerical model, analyzed through different numerical simulations using the Ansys 2025R01 Software package and validated by experimental results, showed a strong correlation between experimental and numerical results that confirmed the reliability of the developed models for preliminary design verification. These models hold significant potential for the design of mechanical and biomedical components, including orthopedic immobilization devices. Microscopic analysis revealed brittle fracture in solid specimens with striations and bubble-shaped irregularities, while Voronoi specimens exhibited fragmented surfaces with clean, brittle failure along structural voids. Based on the results obtained, this research demonstrates how additive manufacturing enables the optimization of mechanical properties and material efficiency through precise control of internal structures. In the future, validated numerical models can be used to check the preliminary designs of different components, which will significantly reduce development costs.

The aim of this research work is investigations of absorption characteristics of a circular seamless tube collision absorber filled by rigid polyurethane (PU) foam under axial load. Shrinking of circular tube passing through cone bushing starts after absorber is activated at the moment of collision. The energy absorption realises in three ways: elastic-plastic deformation of the tube wall, friction between absorption elements and compression the rigid PU foam inside the tube. Using rigid PU foam, as the seamless tube filler, in the process of collision energy absorption increases absorption power in comparing to with only empty tube, as well as gives gradual increases of deformation resistance during deformation process. Experimental research was prepared and realized in the laboratory using the scaled samples. The effect of rigid PU foam, configuration of absorber filled by PU foam on the absorption power and manufacturing technology of the samples, are considered and discussed in this paper. The results indicate that the shrinking foam filled tube absorber has for about 18% bigger absorption power than the empty one. Formation of numerical model and numerical analyses of shrinking foam filled tube absorber were realized using ANSYS software package. Force vs. stroke (F(s)) diagrams obtained by tests and numerical analyses are in a good correlation which confirms formed numerical model as a suitable for further quasi-static analyses and for dimensioning the similar types of absorber.