Selective laser melting (SLM) is an additive technology that allows for the production of precisely designed complex structures for energy absorbing applications from a wide range of metallic materials. Geometrical imperfections of the SLM fabricated lattice structures, which form one of the many thin struts, can lead to a great difference in prediction of their behavior. This article deals with the prediction of lattice structure mechanical properties under dynamic loading using finite element method (FEA) with inclusion of geometrical imperfections of the SLM process. Such properties are necessary to know especially for the application of SLM fabricated lattice structures in automotive or aerospace industries. Four types of specimens from AlSi10Mg alloy powder material were manufactured using SLM for quasi-static mechanical testing and determination of lattice structure mechanical properties for the FEA material model, for optical measurement of geometrical accuracy, and for low-velocity impact testing using the impact tester with a flat indenter. Geometries of struts with elliptical and circular cross-sections were identified and tested using FEA. The results showed that, in the case of elliptical cross-section, a significantly better match was found (2% error in the F_max) with the low-velocity impact experiments during the whole deformation process compared to the circular cross-section. The FEA numerical model will be used for future testing of geometry changes and its effect on mechanical properties.

The reliability of numerical simulations of the structural response of nonhomogeneous materials to high velocity loadings is highly dependent on the used material model and parameters. For nonhomogeneous materials, such as fibres, reinforced concrete is widely used for the Winfrith model, but the question of appropriate material parameters for Ultra-High Performance Fibre Reinforcement Concrete (UHPFRC) under high velocity loadings is still open. The article deals with possible method of inverse identification of material parameters of a UHPFRC slab under blast loading for a Winfrith material model. Possible application is in the field of numerical simulation of protective or critical infrastructure response to blast loading. Experimental measurement of the time–deflection curve through laser scanning using the triangulation method gave us input data for an inverse identification phase conducted in Optislang software. Obtained material parameters from a given range are optimized for blast loading and their Pearson’s correlation coefficient provides us information about their significance for simulation.

The purpose of the paper is to investigate the influence of geometry of charges on the propagation of blast waves. Various shape charges (cylinder,...

Modeling the nonlinear behavior of concrete within the problems of continuum mechanics for designing protective and military structures is now undoubtedly the subject of effort of staff of many scientific institutes. Striving for modeling real nonlinear behavior of concrete through sophisticated material models implemented in an even more sophisticated computing systems based mainly on the finite element method, however, brings with it certain problems. The main problem is especially a lack of knowledge of material constants (parameters) that must be defined to ensure proper function of a particular model. One possibility, which today enables the mentioned problem successfully solved, is the use of optimization procedures in order to find the correct values of the material parameters. Parameter optimization goes hand in hand with experimental investigation of concrete structures, while it trying to find parameter values of used material model of concrete so that the resulting data obtained from the numerical simulation will best approximate the experimental data. This paper deals with parameter optimization of nonlinear material model of concrete, which is implemented in a computing system LS-Dyna, with the use of optimization procedures and experimental data obtained from the direct tensile tests performed on specific concrete test specimens.