Lucjan Śnieżek

Additive manufacturing technologies rely on extensive digital data processing, beginning with 3D-CAD model development and continuing through data preparation, process planning, manufacturing execution, and post-processing operations. As additive manufacturing systems become increasingly adopted...

The modeling of lightweight unmanned ground vehicles (UGVs) with elastomeric tracks presents a challenge due to nonlinear contact mechanics and compliance characteristics that differ significantly from heavy steel-tracked platforms. This study validates a high-fidelity multibody dynamics model of a lightweight tracked UGV, developed in MSC Adams/View, against experimental. For this purpose, the necessary identification tests were also prepared and carried out. The multi-stage validation process utilized the ARAMIS optical measurement system to capture kinematic responses during track belt deflection, motion-resistance tests, and dynamic maneuvers, including acceleration, braking, and obstacle negotiation. The simulations incorporated a segmented track belt model with compliant force elements, calibrated contact parameters, and the full UGV model. The results demonstrated the strong accuracy between numerical models and real objects (track belt and UGV), with a mean relative error (MRE) of 4.16% for track belt deflection and an overall mean MRE of approximately 2.17% for the UGV suspension spring displacements. Following calibration, the simulated motion-resistance force differed by 0.03% from the reference value of 353.4 N. The developed UGV model accurately represents general dynamic behavior. The maximum relative error for the pitch-related angle α1 reached 11.99% during transient motion. This could be caused by geometric simplifications and longitudinal track belt stiffness estimation. The study demonstrates that the model provides a credible representation of the global undercarriage dynamics within the investigated operating conditions and may serve as a basis for subsequent analyses of undercarriage and drivetrain loads, while short-duration peak loads should be interpreted with caution.

The paper presents the model, methodology and results of experimental research focused on identification of the wave form generated during the crossing of 30-ton and 60-ton vehicles on a ribbon-type pontoon bridge and the analysis of its influence on the characteristics of the maximum draught. A review of the literature revealed that ribbon-type pontoon bridges are subject to significant vertical deflection. This results from the need to generate sufficient buoyant force to balance the weight of crossing vehicles. The area of maximum draught occurs directly beneath the vehicle and moves along with it, generating a front wave—referred to as a bow wave—which propagates along the crossing and alters the local draught of individual pontoons. Due to the fact that pontoon bridges transfer loads through buoyancy force, a key issue in the process of their design is the precise knowledge of the formation of the volume of the droughted part. No information was found in any publication about the influence of the front wave on the draught form of a ribbon-type pontoon bridge. Their authors do not indicate that the analytical or simulation models they use reflect this phenomenon. Equally, the analysis of the methodologies and results of experimental studies in this area did not show that any attempts were made to identify the form of the front wave. The paper presents the results of measurements of vertical displacements of individual pontoon blocks of the crossing and the characteristics of the front wave occurring during the passing of 30- and 60-ton vehicles with speeds ranging from 7.4 to 30 km/h. Based on the obtained data, an attempt was made to identify the phenomenon of undulation of the surface of the water obstacle and its impact on the loads on the bridge structure. The results allow for identifying a significant front wave with a wavelength of 30–50 m, appearing clearly at speeds above 21 km/h. This wave substantially affects the draught measurement—at a speed of 25 km/h, the maximum draught increased by approximately 30%. Statistical analysis confirmed the significance of this effect (p < 0.05), indicating that wave formation must be considered for accurate determination of pontoon block draught. Furthermore, the mass of the vehicle had a strong influence on the wave and draught parameters—the 60-ton vehicle produced wave troughs and draught depths 55–65% greater than those of the 30-ton vehicle.

Compared to traditional manufacturing methods, additive manufacturing (AM) enables the production of parts with arbitrary structures, effectively addressing the challenges faced when fabricating complex geometries using conventional techniques. The dynamic development of this technology has led to the emergence of increasingly advanced materials. One of the best examples is metal–polymer composites, which allow the manufacturing of fully dense components consisting of stainless steel and titanium alloys, employing the widely available AM technology based on material extrusion (MEX). Metallic materials intended for this type of 3D printing may serve as an alternative to currently prevalent techniques including techniques like selective laser melting (SLM), owing to significantly lower equipment and material costs. Particularly applicable in low-volume production, where total costs and manufacturing time are critical factors, MEX technology of polymer–metallic composites offer relatively fast and economical AM of metal components, proving beneficial during the design of geometrically complex, and low-cost equipment. Due to the significant advancements in AM technology, this review focuses on the latest developments in the additive manufacturing of metallic components using the MEX approach. The discussion encompasses the printing process characteristics, materials tailored to this technology, and post-processing steps (debinding and sintering) necessary for obtaining fully metallic MEX components. Additionally, the article characterizes the printing process parameters and their influence on the functional characteristics of the resulting components. Finally, it presents the drawbacks of the process, identifies gaps in existing research, and outlines challenges in refining the technology.

The article presents test results concerning the mechanical properties of friction stir welded joints (FSW) and underwater friction stir welded joints (UWFSW) made of aluminium alloy AA7075-T651. The analysis of microhardness distribution revealed two positive effects of water cooling, i.e. the reduction of the heat affected zone (HAZ) and an increase in the microhardness of the low hardness zone by approximately 15 HV0.1. Static tensile test results revealed that water cooling led to an increase in the yield point of the FSW joint by approximately 18 % (58 MPa) and tensile strength by approximately 9 % (43 MPa). Under low-cycle fatigue conditions, the UWFSW joints were characterised by higher stress amplitude, lower plastic strain amplitude and a lower number of cycles preceding the failure (of the UWFSW joints) than that preceding the failure of the “classical” FSW joints.

This study examines the application of additional water cooling on the mechanical properties of AA7075-T651 alloy friction stir welded butt joints. Underwater joints were produced in a wide range of welding parameters and compared to conventional FSW joints in terms of microhardness and basic...

This study aims to analyze the ceramic-metal composite Al2O3/TiO2/TiAl2O5 obtained using the slip-casting method. Samples containing 50% of the solid phase and 2% and 4% fractions of the metallic phase were examined. Rheological investigations were performed. Measurements of shrinkage and density of the composites produced were determined. The phase composition of the obtained composite was investigated using SEM/EDS and XRD techniques. Stereological analysis was performed as well. The slip-casting method enables the production of the proposed composite, reinforced by the presence of TiO2 and TiAl2O5. With the increase in the content of the metallic phase in the composite, the thialite phase content increases, but relative density and volumetric shrinkage of the obtained composites both decrease. Thialite grains are characterized by a size in the range of 4 µm to 15 µm, which leads to a low density of the samples. The results revealed that no significant effect of changing the metal phase content of the slurries used for the composites being fabricated was observed on the limiting grain growth of alumina during the sintering process of slip-casting composites. This finding is important as it suggests that the increase in metallic phase content does not lead to undesirable grain coarsening, which could degrade mechanical properties.

This study investigates the influence of a magnetic field on the microstructure and properties of Al₂O₃–Ni composites fabricated via centrifugal slip casting at 1500 rpm. Al₂O₃ and Ni powders were combined with water and deflocculants, homogenized, and then cast into a porous plaster mold surrounded by Nd-Fe-B magnets. The resulting composites, sintered in a reducing atmosphere, exhibited a three-zone structure with varying Ni content due to the combined effects of the magnetic field and centrifugal force. SEM, EDX, and XRD analyses confirmed the distribution and composition of the phases. Hardness tests revealed the highest values at the outermost zone, with a gradual decrease toward the inner zones. Compression tests employing digital image correlation revealed high internal stresses and a significant improvement in compressive strength compared to non-magnetic field methods. This study confirms that magnetic field-assisted centrifugal slip casting significantly enhances the structural, hardness, and compressive strength properties of Al₂O₃–Ni composites, indicating promising potential for advanced applications.

The material extrusion (MEX) method utilizing highly filled metal filament presents an alternative to advanced additive metal manufacturing technologies. This process enables the production of metal objects through deposition and sintering, which is particularly attractive compared to powder bed fusion (PBF) technologies employing lasers or high-power electron beams. PBF requires costly maintenance, skilled operators, and controlled process conditions, whereas MEX does not impose such requirements. This study compares research on 17-4 PH steel manufactured using two different commercially available techniques: MEX and powder bed fusion with laser beam melting (PBF-LB/M). This research included assessing the density of printed samples, analyzing surface roughness in two printing planes, examining microstructure including porosity and density determination, and measuring hardness. The conducted research aimed to determine the durability and quality of the obtained samples and to evaluate their strength. The research results indicated that samples produced using the PBF-LB/M technology exhibited better density and a more homogeneous structure. However, MEX samples exhibited better strength properties (hardness).

The manuscript presents the results of butt joining of 3-millimeter-thick AlCu4Mg1 alloy sheets using the FSW (friction stir welding) and UWFSW (underwater friction stir welding) methods. The aim of the research is to verify the influence of the water environment on the FSW friction welding process. The article checked three sets of joint parameters. The parameters differed in tool rotation speed and feed rate. The same sets of parameters were used for the FSW and UWFSW fusion techniques. With the supplied devices, metallographic sections are cross-sectioned, and the power supplies are subjected to a light microscope. Microhardness tests and the influence of the heat-affected zone were carried out. A monotonic test was performed. A monotonic test is available, extended with a visual correlation test. The obtained cracked fracture surfaces were examined using a scanning microscope. An analysis of the microfractographic cracking process was carried out. The obtained results did not show any improvement in the strength properties of the obtained joints made using the UWFSW technique when using a scanning microscope.