Volume 5 (2022): Issue 2 (October 2022)

There is a continuous development in automotive body production to expand the use of metal foams. The use of aluminium foams in vehicles is made possible by the high strength/mass ratio, which means that mass reduction is not accompanied by a reduction in safety. Reducing mass (self-weight), on the other hand, is essential due to increasingly stringent environmental regulations. The present composition draws attention to the structural properties of metal-based foams and its testability.

The work focuses on the development of an artificial neural network (ANN) based model that can describe the adsorption of benzalkonium chloride from aqueous solutions onto commercially available kitchen paper. Various ANN architectures were tested in order to find the most suitable one in terms of overlapping between calculated and measured output data (coefficient of determination and mean absolute percentage error), as well as correctly interpolating outputs when using inputs form inside the experimental training range. The networks all had 4 inputs and 1 output, as well as a single hidden layer. Optimal ANN design was sought by varying both the number of neurons in the hidden layer and the type of transfer function towards it. The best find was employed in assessing the relative importance of input parameter values in the output, as well as the model’s suitability for predictions outside the training range.

Extreme Pressure (EP) additives are commonly used in lubricants to reduce wear and prevent seizures at high temperature and pressure. In terms of their mechanism, these build up a film on the surface with chemisorption. This film efficiently prevents metal-metal adhesion. Industrial statistics show that extreme pressure additives are mostly used in metalworking fluids, lubricating greases and engine oils.

Sulfurized vegetable oils can be used as EP additives of lubricants. This type of EP additive is ashless, derived from renewable sources and have a lesser negative effect on the environment compared to those that are not derived from vegetable sources. To determine the appropriate vegetable oils to be used as the raw material of EP additives, the structure of triglycerides, cost-effectiveness and availability aspects must be considered. Results of experiments show that rapeseed oil and soybean oil best meet this criteria system.

One of the most important components of a tube end flaring machine is the flanging tool, which is subjected to mechanical stresses such as compression, bending and abrasion. It is therefore very important to choose the optimal material and manufacturing technology for the flanging tool. Böhler tool steel grades K110 and K340 were chosen as the subject of our research. Both materials were used to produce tube flanging tools, which were subjected to hardness testing, microscopic examination and surface wear testing after simple cooling or deep cooling and triple high temperature tempering after austenitisation in a vacuum at elevated temperature. Based on the measurements, the deep cooled and triple tempered K340 steel was found to be the most favourable tool steel for the production of the tube flanging tool.

Dental fillings are one of the most widespread minimal invasive procedures in modern restorative dentistry. Thanks to the advantages of recently developed filling materials, adhesive systems, and filling techniques, it is possible to create high strength, long-lasting dental fillings. Qualifying these structures is a complicated procedure; the most common method is the use of a microtensile bond strength test, for which specimens need to be formed and stabilised with adhesives in special jigs. During our research, three different cyanoacrylates were examined to find the ideal adhesive for bonding the metal and dentin and the metal and EverX short fibre composite, respectively.

The aim of this work is to design a high-productivity, continuously operating fiber producing device utilizing the centrifugal force to yield polymeric nanofibers. The requirements for the design were 1) to provide a capillary-to-collector distance of 50–200 mm that could be adjusted automatically, 2) allow the rotational speed of the spinneret to be changed in the range of 0–25000 1/min and have continuous feeding. The equipment will form the basis of several research topics, such as the creation and study of solid dispersions of drugs, the development of pressure sensors, and the creation of porous filter membranes.

Beside prosthesis loosening, wear is the mechanical factor that most significantly influences the lifetime of total knee replacements (TKRs), which can only be described by a number of interrelated parameters. The examination of the wear occurring in TKRs is mostly carried out as a combination of experiments and mathematical modeling. The experiment can provide the real magnitude of wear, while the model is intended to mathematically describe the relationship between wear and the wear-inducing parameters. On the one hand, this study focuses on the mathematical description of wear as a natural-technical phenomenon, presenting the most important analytical and numerical models, while also providing an open view on exciting questions that still await answers.

In material-processing fiber lasers, the resonator in the closed box produces the laser radiation. Even with the same resonator, the diameter of the laser beam transporting fiber optics and the properties of the optical elements in the laser focusing head decide the cross-section of the focused laser beam used for machining. If we summarize the formulas in different sources in the literature, we can predict the effect of each optical element: what will happen if we choose another focusing lens, put a beam expander in the system, set on the beam expander how many times the laser beam expands. The other important point is that if we want to repeat an experiment or start a production process based on a scientific publication, then in addition to the resonator, it would be good to know the data of the optical elements in the focusing head, which is usually incomplete in the presented articles, but we can determine them approximately using the four formulas listed in the article.

Arc welding produces several harmful health effects on the welder. The authors aimed to determine the intensity of ultraviolet (UV) radiation as a function of distance from the welding. The research focused on the UV radiation generated during the arc welding process as it is a widely used process in industrial practice today. During the experiment, several tests were performed on the gas metal arc welding process (GMAW). This procedure is also used automated in the industry, so research can help to designate a specific safety zone in an industrial area so that there is no need to separate the welder robot with a curtain, but at the same time be able to move around them. Where the production is not fully automated yet, it highlights the problems which cause possible damage to health and helps create safer working conditions.

This paper investigates the phenomenon of Laser-induced Periodic Surface Structures (LIPSS) on Si single crystals. As usual, by variation of parameters, the morphological and physical properties of the resulting surfaces can be tailored, with respect to their use in many applications. One application-oriented use of LIPSS is the preparation of SERS (Surface Enhanced Raman Spectroscopy) substrates, which can be used to detect extremely low concentrations of molecules. In this experimental work, a possible way of manufacturing of SERS substrates, followed by SERS enhancement testing has been shown.