Biomimetics, biomimicry and bionics are synonyms for the scientific discipline of creating new structures inspired by nature. Biomimetics systematically analyses the evolutionary processes of living organisms, their structural relationships, the characteristics of natural materials and it studies how this knowledge can be used to create the optimal products and new sustainable materials. In the past decade, the biomimetics has received an incentive for the development by the technology modernization, and above all, by making it possible to study the microand nanolevels of biological structures. On the other hand, the miniaturization of technological devices has increased the need to understand the tribological phenomena on micro-and nanolevel, where is a huge potential for technological innovation. The integration of advanced research methods made it possible to discover new aspects in the structure and properties of biological materials and transfer that knowledge into new concepts or products. State-of-the-art of biomimetics progress is discussed, as well as, its goals and the potential to simultaneously achieve the financial and ecological contribution by realization of bio-inspired concepts. An overview of biomimetic researches is also provided, with special emphasis on the possibility of their tribological applications. The characteristic examples have been presented and those examples show how the structural and mechanical properties of the material were used as the basis for developing new creative solutions to solve the problem of friction in engineering applications.

This paper presents research of the impact toughness and hardness distribution in specific zones of a ‘single V’butt multiple-pass welded joints of the high-strength low-alloyed steels. Obtained values of the impact toughness are analyzed in correlation with a microstructure in specific zones of the welded joint, together with the micro hardness distribution found in the related zones. Based on the carried out analysis and results obtained in experiments, the applied technology of welding was evaluated. The original conclusions on influence of the selected welding procedure manual metal arc (MMA) for the root passes and metal active gas (MAG) for the filling and covering passes) on impact toughness of the high-strength low-alloyed steels are drawn. The paper also presents discussion on the valid standards and recommendations related to welding of those steels, from the aspect of applications in design of steel welded constructions.

This paper explains development of the general mathematical model of trochoidal gearing that can be applied for gerotor pumps and cyclo reducers. The model analyzes geometry and physics of the gearing pair in trochoidal pump where the outer gear has one tooth more than the inner gear. The inner gear profile is described by peritrochoid equidistance and the outer gear profile by circular arc. Mathematical model of gearing with clearances is based on the principle of an ideal profile development. Minimum clearance height between teeth profiles in relation to instantaneous gear ratio is determined. The influence of gear profile geometrical parameters on gearing process, clearance height change, and pulsation of drive moment is analyzed and presented in numerical examples. Obtained results can be used for the design of the trochoidal gearing where accurate and silent operation is required.

Surface texturing is one of the surface modification techniques which deliberately change the texture of the surface, in order to improve, among other things, its tribological performance. This is obtained through different patterns, which can be on micro or nano scale, created on the contact surfaces. The performance of a textured surface depends on the shape, geometry and pattern of the surface texture and the operating condition of the components in contact. There is a number of various techniques for surface texturing, among which laser surface texturing is most often used. The different surface texture shapes, different textured area ratios and patterns, different lubrication regimes with different contact geometries and materials have been subject of theoretical and experimental research for many years. This paper reviews the state-of-the-art of researches that consider various surface texturing for tribological application, as well as its effect on performance enhancement. Conclusions of this paper may provide guidance for optimal design of surface textures in practical engineering applications.

This article presents the analyses of the forces and moments between gears in contact with a gerotor pump. The objective was to reach a more accurate solution for the problems related to load distribution in trochoidal pumps with fixed shaft axes. Calculation of contact forces is complex due to the simultaneous contact of several trochoidal teeth during the load transfer and additional compressive fluid forces that act on the teeth flanks. A simple physical model and a suitable analytical model are used for this analysis. Compressive fluid forces are simulated with single force applied in the middle of the line that separates the suction and upward pressure zone. During the teeth engagement there is also a change in fluid volumes between teeth. This creates pressure change that needs to be considered and calculated at an arbitrary moment of the engagement process. Finite element analysis (FEA) was used to determine the reaction forces that depend on instantaneous moments as well. Analysis shows that if a chamber pressure variation is taken into account, higher values of driving moment and support reaction forces will be generated. Designers can use the obtained results to develop a higher efficiency gerotor pumps.