Analysis of the Mechanical Properties of 3D-Printed Plastic Samples Subjected to Selected Degradation Effects.

The Fused Filament Fabrication (FFF) method is an additive technology that is used for the creation of prototypes within Rapid Prototyping (RP) as well as for the creation of final components in piece or small-series production. The possibility of using FFF technology in the creation of final products requires knowledge of the properties of the material and, at the same time, how these properties change due to degradation effects. In this study, the mechanical properties of the selected materials (PLA, PETG, ABS, and ASA) were tested in their non-degenerate state and after exposure of the samples to the selected degradation factors. For the analysis, which was carried out by the tensile test and the Shore D hardness test, samples of normalized shape were prepared. The effects of UV radiation, high temperature environments, high humidity environments, temperature cycles, and exposure to weather conditions were monitored. The parameters obtained from the tests (tensile strength and Shore D hardness) were statistically evaluated, and the influence of degradation factors on the properties of individual materials was assessed. The results showed that even between individual manufacturers of the same filament there are differences, both in the mechanical properties and in the behavior of the material after exposure to degradation effects.

Assessment of military preparedness for naturogenic threat: the COVID-19 pandemic in the Czech Republic.

This article deals with the provision of cooperation of the Army of the Czech Republic with other units of rescue teams in the implementation of rescue and liquidation work in the regions of the Czech Republic in non-military crisis situations. At the present time of the global pandemic of covid-19 and the associated mass deployment of forces and resources of the primary and secondary units of the rescue system, the required effective cooperation in practice has proved necessary. The paper deals with the analysis of emergency management in a state of emergency in order to contribute to the improvement of civil-military cooperation. Based on the results of the research survey, the authors proposed evaluation criteria for determining the level of emergency preparedness of the forces and resources of the Army of the Czech Republic.