Investigations of defects and their spatial distribution in iron and silver irradiated with swift Xe 26+ ions of different energies: 18.5, 45.5, 122.5 and 167 MeV have been performed using conventional positron lifetime spectroscopy. In the implanted layer, in which the ions are stopped, dislocations and clusters of vacancies were found in iron and only dislocations in sliver. In both metals, an extended layer of damage with defects was detected beyond the implanted layer. The origin of this extended layer can be explained by the depth distribution of the stress caused by swift ions in the implanted layer. The calculations using a finite element method indicates that the stress value in the implanted layer, i.e., about 1 GPa for iron and 0.5 GPa for silver exceeds several times the yield strength.

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We present an adaptation of the multiscale finite element method to the analysis of sandwich beams and plates with complex lattice layers. The proposed modification significantly reduces the number of degrees of freedom (even by four orders) due to the anisotropic higher-order coarse-scale approximation and the novel shape functions that take into account the microscale boundary conditions. Moreover, the local iterative corrector scheme Nguyen and Schillinger (2019) adapted for the bending-dominated responses of sandwich structures provides converges of the coarse mesh approximation to the best possible fine-mesh solution. Several numerical examples are presented to demonstrate the capabilities of the method. We found that the proposed modifications of the shape functions and the higher-order coarse mesh approximation increase the convergence rate. Finally, we validated the proposed model by comparison of the numerical results with experimental ones for a sandwich panel with a dual corrugated high-density fiberboard core. Very good consistency of both results was observed.

Positron annihilation lifetime spectroscopy was used to study acrylonitrile butadiene styrene (ABS) specimens manufactured using fused deposition modelling to explore possibilities of identifying differences in molecular structure. The set of specimens was prepared including square tiles and long rectangular tiles (100 mm and 200 mm long) with all filament roads parallel to the longer edge. All types of tiles were produced with various infill line distance parameter resulting in different overlapping of the roads in horizontal and vertical directions. The slight increase of the ortho-positronium lifetime indicating increase of the mean free volume radius was observed for the longest tiles for which influence of weld interface is expected to be most pronounced. No differences were observed for different infill line distance parameters.

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