The article presents a concept of a lunar base that would take advantage of the natural shape of an egg. Several versions of egg-shaped habitat structures characterized by different sizes are presented. Possible locations of habitats both on lunar surface and in craters were discussed. Advantages and disadvantages of particular locations were also pointed out. The proposed in the paper concept of an egg-shaped structure is characterised by a spatial character based on Voronoi diagram and would be implemented using a 3D-printed method. The presented 3D-printed structure was designed to be light and suitable to be covered by lunar soil. As a necessity in the developed concept, in situ resources utilization was addressed in order to generate products using local sources to reduce the number of materials that would be required to be transported from Earth. At the end of the paper, future areas of research and tests are highlighted.

Tensile membrane structures combine a prestressed roofing envelope material and supporting elements. To design these structures, there is a set of recommendations in the European Design Guide for Tensile Surface Structures and some other national standards. However, currently, there is no official standard related to the design process of tensile structures in the European Union. The structure studied in this project is considered as permanent roofing of an external testing device in the shape of a simple hyperbolic paraboloid without enclosing walls. Snow and wind loads were analyzed as the most critical types of loading in the location. Determining the value of the snow load is relatively simple according to the European standard. However, in the case of the wind load, this shape is not considered in the European standard and needs to be solved experimentally or by numerical simulation in a wind tunnel. The present contribution focuses on numerical analysis of the wind flow in RFEM software and simulation of the wind tunnel in RWIND software.

The principle of FFF/FDM (Fused Filament Fabrication/Fused Deposition Modeling) 3D printing technology is the melting and application of a continuous fiber made of thermoplastic material, according to predefined routes on the substrate. A layer is created on which other layers are placed until the object is finished. It is the orientation of these fibers that greatly affects the resulting mechanical properties. Therefore, the printed object behaves orthotropic. The material does not blend perfectly or evenly between the individual fibers, which is why the resulting strength is limited by adhesion. Within the fibers themselves, it is also its dimension that affects the size of the contact surface and therefore the effect of adhesion. This contribution aims to compare the effect of fiber size in a given direction and its rotation in 3-point bending according to the standard ČSN EN ISO 178. The maximum bending load force was obtained and the bending stress and modulus of elasticity were determined. The influence of layer cohesion on the failure of the specimens is compared. One of the other important studied aspects for the effective production is the printing time of each specimen.

The research presented in this article aimed to investigate the differences in mechanical properties between solid structural timber and the same reinforced element in three different ways. A three-point bending test was performed on wood elements reinforced with carbon-fiber-reinforced polymer (CFRP), 3D printed polycarbonate (3DPC) lamellas, and 3D printed polycarbonate with carbon fiber (3DPCCF) lamellas. In this comparison, the bending strength was large for CFRP samples, which have 8% higher performance than samples with 3DPCCF and 19% higher performance than samples with 3DPC. Conversely, when factoring in theoretical manufacturing costs, the performance of 3DPCCF is almost three times that of CFRP and 3DPC. In addition, 3D materials can be used for more complicated reinforcement shapes than those discussed in the paper.

This paper presents numerical models of a 3D printed plastic joint applicable to the connection of wooden structures. The research presented provides a comparison of two alternative solutions for the geometry of the joint and results from several loading schemes and boundary conditions. Included are analyses evaluating the mechanical behaviour in a simple axial tensile test, a three-point bending test and, finally, a sensitivity analysis of the location susceptible to fatigue damage. The models include a 3D printed polycarbonate joint, wooden elements and steel shear pins. The combined model allows a deeper understanding of the interactions. Finite element method (FEM) software was used to develop the numerical models and suitably defined boundary conditions, and material properties of all parts were adopted. The simulation results show that the 3D joint exhibits a high resistance to tensile loading, while in the case of three-point bending, a higher susceptibility to fracture of the printed joint is observed. The sensitivity fatigue analysis identified critical areas on the 3D printed component that need to be improved before further development. These analyses provide important information for optimizing the design of 3D printed plastic joints intended for wooden structures.

In the last decades, 3D printing technology has evolved at a revolutionary pace, as well as its use. By creating a precise virtual model, it is possible to prin