Advances in Science and Technology Vol. 181

Abstract: Many components in the automotive industry have rubber material in their composition, which makes the role of rubber critical in many systems of vehicles, particularly suspension systems, where it works as vibration isolators and energy absorbers to protect the system against impact loads. In the medium and heavy-duty vehicles, rubber bumpers are in the air spring assemblies, working as a secondary load-bearing element, ensuring the safe operation when the air spring reaches its maximum compression. Despite that, rubber’s complex, nonlinear, and hyperelastic behavior impacts the prediction of the bumper’s mechanical response, consequently being a big design challenge . The experimental test to understand rubber’s characteristics is often expensive and time-consuming, making Finite Element Analysis a good alternative for studying deformation and stress distribution under realistic constraints. This study investigates the finite element behavior of an axisymmetric rubber bumper exposed to compressive loads. The bumper assembly model was designed in CATIA V5 and simplified into a two-dimensional model to enhance computational effectiveness. The model establishment was done in ANSYS, where all the details necessary to replicate the exact operating environment of the bumper were taken into consideration. The post-processing focused mainly on the force-displacement response, with additional simulations that reviewed how some parameters affect the results. The investigation provides valuable information about the structural response of rubber bumpers and establishes an effective approach for future design and optimization of this suspension component.

Abstract: The article introduces the possibility and process of the development of a tool changer mechanism. The component in this article is the most important one of the automated tool supply system of modern machine tools. The development direction of newly designed machine tools is mainly determined by the increase in operating speed and efficiency, which is required by industrial expectations. In the complex kinematics of the tool supply system, mass reduction can result in a large decrease in case of energy requirements. In addition to economical operation, harmful dynamic effects can also be diminished. During technical design and development, the choice of design approach and design tool system is important, as the optimal solution can only be considered successful if its technical and economic implications meet the expectations. Thanks to modern computer technology tools, various design-aiding procedures have been created that complement classical design methodologies and help the work of design engineers. Optimization methods (CAE) common in computer-aided design systems (iCAD), such as topology optimization (TO) and the new generative design process (GD), provide effective solutions for design engineers in an increasing number of industrial application areas. Based on the experience gained in product development, it can be observed that simulation-driven design methods can be applied in various areas of industry. The case study of the article presents the computer-aided design process and its characteristics and details the tasks to be performed in each step and also summarizes its effectiveness.

Abstract: The article introduces the design of a frame element of a Giant AC bicycle manufactured in 2003. The development work focuses on the component connecting the spring and the rear swingarms. The process is assisted by the tools of the discursive design approach and the simulation-driven design method. The component in the case study was designed by the usage of the tools of the given time, when diverse design software and affordable high-capacity computers were not yet available. Nowadays, iCAD design systems support engineering work with appropriate CAE target software, which allows the examination of virtual prototypes with adequate accuracy. The concept-forming properties of topological optimization (TO) and generative design (GD) fit into the discursive design approach and provide effective solutions in an increasing number of fields of application. The simulation-driven design process in this article is executed in Siemens NX 2506 software. The case study details the steps of the development process. It presents a kinematic description of the investigated component for several purposes. In the generation phase, the creation of solutions was influenced by various aspects, such as the starting geometries, the raw materials that can be used, and the manufacturing technologies that can be matched with them. A technical value analysis is executed for the different solutions, which aims to help the selection of the best design. The scope of use of the bicycle is close to competitive sports, therefore, the weight of the component is an important aspect in case of value analysis. The article introduces a comparison of the original component and the one produced by using modern methods and summarizes the achieved results.

Abstract: Reversible ploughs are modern agricultural implements that allow ploughing operations to be carried out with increased efficiency by turning the furrows in the same direction, regardless of the movement direction of the tractor–plough unit. Their functionality is ensured by a reversing mechanism, typically actuated by a hydraulic cylinder, which rotates the movable frame by 180° around the tractor's longitudinal axis at the end of each pass. This paper presents a static analysis of such a mechanism, with the objective of determining the distribution of mechanical stresses, displacements and equivalent deformations, as well as the safety factor of the main structural components. The applied methodology included defining the three-dimensional geometric model of the reversing assembly and performing numerical simulation using the Finite Element Method (FEM), with the SolidWorks Simulation software. The calculation assumptions considered the maximum load generated by the hydraulic cylinder during the rotation phase, with proper application of contact conditions and mechanical constraints. The results highlighted equivalent stresses, calculated according to the Von Mises criterion, below the allowable limits for the materials used, displacements and deformations within functional limits, and safety factors ranging from 2.1 to 3.5 for critical components (rotation shaft, support frame, and cylinder attachment points). The conclusions of the analysis confirm that the mechanism’s design is appropriate for the static loading conditions encountered during regular agricultural operation.

Abstract: This study investigates the influence of fiber and CO₂ laser cutting parameters on the material properties of wear-resistant Hardox 450 steel. The research focuses on the: effect of laser power, assist gas pressure, and cutting speed on the microhardness and surface integrity of the cut material. A full factorial experimental design was employed, consisting of 162 specimens cut under different process conditions. Hardness was evaluated using the Rockwell method, while surface roughness was measured with a Mitutoyo SJ-210 profilometr. The results revealed that gas pressure and laser power have a dominant effect on hardness variation in the heat-affected zone (HAZ), whereas cutting speed significantly affects the surface roughness.A comparative analysis between fiber and CO₂ laser technologies showed that fiber laser cutting produces a narrower HAZ and better preserves the base-material hardness, minimizing microstructural degradation. In contrast, CO₂ laser cutting results in a wider HAZ with slightly reduced hardness but improved smoothness due to longer thermal exposure. Statistical analysis (ANOVA) and regression modelling enabled the identification of key interactions between process parameters and material response. The study contributes to a deeper understanding of the laser–material interaction mechanisms in high-strength steels and provides recommendations for optimizing cutting conditions to maintain the mechanical integrity of wear-resistant materials.

Abstract: The use of geometric tolerances is becoming increasingly common in the field of mechanical engineering, especially for parts with complex shapes and tight tolerances. The tolerancing process, which determines the type and size of tolerances to be applied, requires a multi-purpose analysis. Tolerancing considers the analysis of functional requirements, manufacturability considerations, the proper application of drawing specifications, and the measurement process. In our research, the cylindricity and circularity errors of machined holes are examined as a function of machining parameters and circumstances in different steel materials. The holes investigated in this article were made using three different machining processes - turning, boring and milling - from C45 steel. The aim of the article is to present the least square (LS) and minimum zone (MZ) methods for evaluating the cylindricity error, and to compare the results of the two analyses by statistical methods. In addition to the evaluation based on 264 points recorded on a coordinate measuring machine, the article also presents the deviation of the point cloud created using the Halton-Zeremba point sampling method, demonstrating the effect of the number of measurement points on the value of the cylindricity error and the diameter.

Abstract: This research presents a model for calculating the productivity of metal removal during external cylindrical grinding, taking into account the instability of the technological process during the workpiece operating cycle and during the processing of a set of products. The relationship between the productivity of the grinding process using CNC digital control systems and the cutting forces, the physical and mechanical properties of the machined material, the properties of the grinding stone, the rigidity of the technological system, cutting systems, the characteristics of layer removal in areas opposite the wheel rotation, the achieved machining accuracy, and other technological factors affecting the process.

Abstract: One of the primary drawbacks of the micromilling process is the limited lifespan of micro end mills, which significantly increases the cost of production. In addition to its brevity, the tool life is also stochastic in nature, making it challenging to predict and avoid untimely tool changes during the micromilling process. Despite the numerous attempts to estimate tool life, minimal attention has been paid to the feasibility of the ensemble machine learning models. Yet, they carry great potential for online tool status monitoring frameworks, which is the future of smart machining, a pillar of the Industry 4.0 industrial revolution. The aim of this work, therefore, was to develop an ensemble model for accurate tool life prediction and optimization. Data collected from a tool life experiment series involving the machining of a polymer-graphite composite were used to train and test a stacking regressor. The resultant model had an MAPE of 1.87%, an R² of 0.92 on both the training and testing data, as well as a R_adj² of 0.91, which are statistically significant. The model outperforms an empirical multilinear model, previously modelled using the same data, whose MAPE is 5.08 %, R² is 0.89 and R_adj² is 0.84. The stacking regressor is later used successfully in the whale optimization algorithm (WOA) to optimize tool life, and optimal cutting velocity (65.72 m/min), axial depth of cut (0.96 mm), and feed (26.16 µm) are proposed for the efficient micromilling of the polymer graphite composites, which are used for the fabrication of bipolar plates needed for hydrogen fuel cells.

Abstract: The paper presents an experimental study focused on the wear of cutting inserts during the processing of waste construction glass, which is often laminated with a plastic film. Due to the continuously increasing amount of glass waste generated from construction, demolition, and the dismantling of photovoltaic panels, efficient glass processing and recycling have become significant environmental and technological challenges. Glass represents a material with high recycling potential; however, its composition, the presence of laminated layers, and its abrasive properties make mechanical processing difficult. The main objective of the research was to quantify the wear rate of the cutting inserts based on their mass loss during the mechanical crushing and layer separation process. The study was carried out using a novel mechanical scraping principle that enables efficient separation of glass from the polymer film while maintaining the integrity of the interlayer, making it suitable for further use. The cutting inserts were made of wear-resistant Hardox 500 material and were tested with various types of surface treatments. The aim was to evaluate the influence of these treatments on the wear rate and to assess their technical and economic effectiveness. The obtained results provide new insights into the influence of the abrasive properties of construction glass on the service life of cutting tools, as well as into the suitability of different surface treatments in glass recycling processes from photovoltaic and construction applications.

Abstract: This study presents a numerical investigation of failure initiation and evolution in thin-walled extruded aluminum tubes subjected to three-point bending and dynamic axial compression. An explicit finite element framework is employed, combining the Müschenborn--Sonne forming limit diagram (MSFLD) with stress-state-dependent ductile and shear fracture criteria to capture multiple competing failure mechanisms. The approach accounts for instability-driven necking as well as fracture governed by evolving stress triaxiality and Lode parameter. Numerical predictions are validated against experimental results through both quantitative comparison of load-displacement responses and qualitative assessment of deformation patterns and fracture locations. The results demonstrate that incorporating stress-state-dependent fracture criteria significantly improves the predictive accuracy of crash simulations involving thin-walled aluminum structures.