FSW is a solid-state joining process. It is widely used for joining hard alloys like steel, titanium, and aluminium which are very difficult to join by fusion welding. FSW joint quality is mainly influenced by shoulder and pin geometry, its diameter, tool material, tool rotation speed, and linear traveling speed. The paper presents a brief overview of the tools used during the FSW procedure. The influence of the tool pin on the material flow and mixture was analysed in detail. In addition, the primary and secondary material flow and how it is affected by the shape and dimensions of the tool pin are also discussed.

This paper presents the results of an experimental investigation into the mechanical properties and quality assessment of welded joints and their corresponding base materials. The study focuses on high-strength armour steels, a class of steel that due to their high hardness and toughness under dynamic impact loads, are utilized in specialized protective structures. The primary objective was to evaluate the performance of the welded joints produced by a specific welding technology and MAG welding process and to compare their characteristics with those of the unaffected base metal. Tensile testing was conducted on a universal testing machine equipped with appropriate instrumentation for precise measurement of force and elongation. A total of 27 specimens were tested, including both transverse welded samples and base metal reference samples, ensuring a comprehensive dataset. The tests allowed to determine key mechanical parameters, including yield strength, ultimate tensile strength, percentage elongation after fracture, and reduction of area. Beyond the numerical results, a fractographic analysis was performed, with particular attention given to the location and morphology of the fracture. The fracture surfaces were examined to determine whether failure occurred in the weld metal, the heat-affected zone (HAZ), or the base material, providing critical insights into the weakest link of the joint. The obtained results were analysed to assess the efficiency of the welding MAG procedure.

Above-ground cylindrical steel tanks are indispensable assets in water and wastewater infrastructure. In equalization services, they buffer diurnal and industrial inflow variability, dampen “shock” pollutant loads, and stabilize downstream treatment functions, consistently shown to improve effluent quality and operational resilience. Even when tanks are designed and operated within code provisions, long-term performance depends on how structural demand interacts with the service environment and maintenance practices. The technical literature documents characteristic failure modes – loss of containment by corrosioninduced wall thinning, local joint distress, and roof/shell instabilities – through forensic case studies that combine inspection, measurement, and finite-element analysis to reconstruct the damage sequence and define preventive measures. Wastewater headspaces and wetted zones present particularly aggressive conditions for carbon and stainless steels due to variable pH, dissolved sulfides, chlorides, and microbiologically influenced corrosion. Recent reviews emphasize corrosion monitoring and mitigation as central to lifecycle reliability of storage and process tanks in treatment facilities. Within this broader context, this study focuses on durability-oriented design, inspection, and riskinformed maintenance programs for tanks operating in wastewater service, drawing on established roles of equalization, observed failure mechanisms, and evidence from prior research and case histories.

Introduction/purpose: The paper presents a numerical simulation of an impact of a 12.7 mm projectile on an armored metal plate with a velocity of 500 m/s at a distance of 900 m. Numerical simulations offer the possibility of drastically reducing the time required to obtain results in comparison to the time required for planning, organization and execution of experiments. The numerical simulation is done by variations in the thickness of the armor metal plate, specifically an armor metal plate of a thickness of 10 mm, 17 mm, 18 mm, and 23 mm. The mentioned armored plate thicknesses were chosen based on the results in order to determine the limit thickness of the armored plate for the projectile perforation limit, as well as for complete ballistic protection. Methods: Finite element modeling is used for analyzing stresses and deformations of the armored plates. The mentioned method calculates the impact of the projectile on the obstacle, precisely the collision of the projectile and the armor plate. Results: For the comparative analysis, the parameters used are the values of the stress and the displacement. For each of the above-mentioned thicknesses of the armored metal plate, the values of stress and displacement during projectile impact were determined. The results of this study show how the thickness of the armor plate affects the interaction of the projectile and the armor plate. Conclusion: If the physical and chemical characteristics of the armored plate remain unchanged, as the thickness of the armored plate increases, the possibility of projectile penetration decreases, and vice versa. This research is of essential importance because it analyzes the stresses and deformation of armor plates whose basic role is the protection of personnel and equipment from the projectile impact. In this regard, the thickness of the armored plate for semi-penetration of the projectile is determined.

This paper presents an analytical and numerical benchmark verification framework for explicit time integration procedures applied to the one-dimensional wave equation. The study combines an exact analytical solution, a closed-form discrete central-difference solution, and explicit finite element models implemented in LS-DYNA and in the in-house academic FEM code PAK-Multiphysics. Two benchmark problems with the same first sinusoidal spatial mode and homogeneous Dirichlet boundary conditions are considered. The first problem, defined by sinusoidal initial displacement and zero initial velocity, is used to analyse the central-difference discretization and its convergence behaviour. The closed-form discrete response enables direct comparison with the analytical solution and confirms the expected second-order accuracy under coupled mesh and time-step refinement at a fixed Courant number. The second problem, defined by zero initial displacement and sinusoidal initial velocity, introduces a phase-shifted temporal response suitable for explicit finite element verification. Four meshes are analysed over five periods of the first longitudinal mode. The numerical responses are assessed using displacement histories, maximum absolute errors, RMS errors, relative RMS errors, amplitude errors, and an energy check. The PAK-Multiphysics results show very close agreement with the analytical solution and a systematic reduction of the error measures, consistent with the lumped-mass central-difference formulation. The LS-DYNA results provide an independent commercial-code comparison, showing decreasing displacement errors under refinement and bounded total-energy variation. The proposed framework provides a transparent and reproducible benchmark for verifying one-dimensional explicit wave propagation models.