Engineering Transactions (formerly Rozprawy Inżynierskie) is a refereed international journal founded in 1952. The journal promotes research and practice in engineering science and provides a forum for interdisciplinary publications combining mechanics with: Material science, Mechatronics, Biomechanics and Biotechnologies, Environmental science, Photonics, Information technologies, Other engineering applications. The journal publishes original papers covering a broad area of research activities including: Experimental and hybrid techniques, Analytical and numerical approaches. Review articles and special issues are also welcome. Following long tradition, all articles are peer reviewed and our expert referees ensure that the papers accepted for publication comply with high scientific standards. Engineering Transactions is a quarterly journal intended to be interesting and useful for the researchers and practitioners in academic and industrial communities. Occasionally, special issues of the journal may be devoted to publication of all or selected papers presented at international conferences or other scientific meetings. However, all papers intended for such an issue are subjected to the usual reviewing and acceptance procedure.
Institute of Fundamental Technological Research Polish Academy of Sciences
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Investigation of the Effect of Fin Geometry on the Thermal Performance of Microelectronics Devices
This study systematically evaluates optimal heat sink geometry for enhanced thermal performance in electronic cooling applications. ANSYS-Icepak and COMSOL Multiphysics software assessed four distinct fin geometries (square, rectangular, circular, and conical), all uniformly sized for accurate comparison. Vital performance parameters were analyzed, including maximum temperature reduction, pressure drop, and airflow velocity. These indicators provide a holistic assessment of cooling efficacy and aerodynamic characteristics. Findings highlight the effectiveness of rectangular fins, which significantly reduce maximum temperatures due to their efficient balance of conductive and convective heat transfer. While conical fins display lower pressure drops and circular fins achieve higher airflow velocities, these attributes do not consistently enhance cooling capabilities. The importance of this study resides in its provision of definitive guidance for selecting fin geometry in designing efficient heat sinks, crucial for electronic devices. This knowledge is particularly vital for developing advanced cooling systems in compact, high-power electronics, underscoring the significant impact of fin geometry on overall thermal management efficiency. Quantitative data supporting these findings is available in the full study.
Copyright (c) 2026 Sana J. Yaseen, Ali K. Hadi, Ali A. Abed, Abdel-Nasser Sharkawy https://creativecommons.org/licenses/by/4.0
Exploring the Synergistic Influences of Clay Nanoplatelets and Waste Eggshell Particles on PMMA-Based Hybrid Nanocomposites
This study investigates the impact of incorporating clay nanoplatelets and waste eggshell particles into polymethyl methacrylate (PMMA) to develop hybrid nanocomposites with improved mechanical and structural properties. Waste eggshells, rich in biogenic calcium carbonate, were utilized as a sustainable, low-cost filler, while clay nanoplatelets provided nanoscale reinforcement and improved interfacial bonding. Hybrid nanocomposites were prepared with 5 wt. % of filler contents using the solution casting method. Scanning electron microscopy (SEM) was employed to examine the dispersion and morphology of the fillers within the structure of the PMMA matrix. At the same time, Fourier-transform infrared spectroscopy (FTIR) was utilized to assess the powder chemical interactions and potential bonding between the fillers (clay nanoplatelets and eggshell particles). Mechanical behavior was also evaluated through tensile testing of PMMA and its produced hybrid nanocomposites. The results indicate a synergistic enhancement due to the combination of organic biowaste and inorganic nanoclay, offering a promising route for the development of sustainable, high-performance polymer nanocomposites.
Copyright (c) 2026 Sameer F. Hamad, Aya Waleed Abd, Anwer J. Al-Obaidi, Nazar J. Abdulridha https://creativecommons.org/licenses/by/4.0
Challenges of Corrosion, Wear, Erosion, and Abrasion in Hydropower Plants: Materials, Modeling, and Mitigation Strategies
The chemical, food processing, hydropower, thermal power, and oil industries are among the sectors that frequently face the problems of erosion, abrasion, and corrosion. Pipelines, elbows, reducers, separators, tees, and seals are among the hydraulic devices and pipeline components that are impacted by these difficulties. Silt erosion in turbines and related parts is a major issue in hydropower plants, particularly in Indian hydropower plants where rivers contain hard elements like feldspar, quartz, and other minerals. Remarkably, more than half of the quartz in the silt causes problems in turbines, including sediment erosion, leaks, and secondary flow disturbances. Hydropower plants' total efficiency is ultimately jeopardized by these issues. This paper aims to support scholars and researchers by highlighting the following topics: (i) component failures in impulse and response turbines used in hydropower projects; (ii) different turbine materials and their properties; and (iii) a comparison of several thermal spraying techniques for turbine materials along with numerous numerical models of erosion and abrasion informed by silt characteristics, material properties, and flow phenomena in different hydro-turbines. The study also discusses modeling, pilot plant loops, wear mechanisms, and protective techniques aimed at mitigating wear and safeguarding hydro turbines.
Copyright (c) 2025 Harvinder Singh https://creativecommons.org/licenses/by/4.0
Modeling Defect Detection in 3D-Printed Structures Using Ultrasonic Guided Waves
Carbon fiber-reinforced thermoplastic composites are widely utilized in 3D printing via the fused filament fabrication (FFF) process. However, defects within printed components can compromise their performance. This study investigates the application of ultrasonic non-destructive testing (NDT) techniques for structures manufactured through FFF. Common printing defects, such as weak interlayer bonding, surface imperfections, and internal cracks, are simulated using a finite element (FE) model. The model analyzes how guided ultrasonic waves interact with these defects. The proposed methodology incorporates digital transducer control and evaluates the energy distribution across incident, reflected, and transmitted wave modes. Three representative defect types are modeled, and the approach is applied to two structural geometries: plates and pipes. The study investigates the correlation between defect size and the behavior of energy reflection and transmission. A signal processing approach is applied, using transducers positioned symmetrically along the wave propagation axis to detect mode conversion and analyze wave reflections and transmissions. The phenomenon of mode conversion is analyzed in detail, and the results are validated by ensuring energy balance consistency.
Copyright (c) 2025 Ismaine Zitouni, Hassan Rhimini, Abdelkerim Chouaf https://creativecommons.org/licenses/by/4.0
Collision Integral for Non-Equilibrium Distributions of 1D Bosons with Non-Linear Dispersions
In order to understand transport phenomena in a quasi-classical regime the Boltzmann transport equation (BTE) is one of the most frequently used tools. Therein, the key quantity is a collision integral – the quantity that encapsulates the properties of the medium under consideration. Usually the result of this integral is approximated by one single parameter, the relaxation time. However it leaves one wondering if such situation is sufficient: for instance, if the dispersion of bosons is non-linear then what will be the influence of this non-linearity on the BTE. Here we give a fully analytic solution of the collisions’ integral for 1D bosonic gases with non-linear dispersion and far out of equilibrium. Our analytic result is given in terms of the Lerch transcendent function and it has been obtained for the case of two sub-systems (one dragging another), by taking a maximum-entropy displaced Bose–Einstein ansatz for their distributions. Currently, there are numerous experiments performed far away from equilibrium, where distributions are massively shifted and our result will serve as a main building block to derive distributions of bosons, and later linear and nonlinear transport coefficients, in such regimes.
Copyright (c) 2025 Piotr Chudzinski, Wieslaw Larecki https://creativecommons.org/licenses/by/4.0
Global buckling of a thin-walled T-frame with consideration of the shear effect
The work concerns the global elastic buckling problem of a thin-walled T-frame with consideration of the shear effect. A novel approach was used to account for this effect namely the non-linear shear deformation theory which gives as a result the shear deformation function describing the behaviour of the beam cross-section. This thin-walled T-frame consists of horizontal beam and vertical column made of the same standard H-beams. The shape of this standard H-beam and the dimensionless deformation function of the plane cross-section, being the result of the shear effect, are analytical described. The buckling problem of the frame is analytically formulated and solved. The critical loads of exemplary beams are analytically determined. Moreover, a numerical FEM model of the frame is elaborated and the critical loads of exemplary frames are determined. Consequently, the research results obtained by both methods are compared and the advantages of the proposed approach is discussed.
Copyright (c) 2025 Krzysztof Magnucki, Paweł Jasion https://creativecommons.org/licenses/by/4.0
Analytical Approach and Shooting Method Solution of Nonlocal Eringen Elasticity Problem of Nanorods
The aim of this paper is to study the postbuckling behaviors of the nanorods combined with the small scale effects. In this paper, buckling of a nanorod column subjected to tip load is investigated. The nanorod is on a clamped support at one end, while the other end is simply-supported subjected to axial compression. At this end, the nanorod is movable only in a horizontal direction. The governing differential equation describing the behavior of the nanorod is developed by the moment–curvature relationship in analogy with the classical Euler–Bernoulli beam theory together with the equilibrium equations, including the effects of nonlocal elasticity as well as corresponding boundary conditions. The numerical shooting methods are derived and employed to solve the differential equations in this problem. The results, including nonlocal elasticity, reveal that nanorods have decreased structural stiffness and show the significant effect of geometrical parameters on the stability of buckled nanorods, emphasizing the importance of accounting for their interaction in the design of nanostructural systems.
Copyright (c) 2025 Aleksandra Manecka-Padaż, Ewa Eliza Rożko, Zdzisław Nowak , Piotr Chudzinski https://creativecommons.org/licenses/by/4.0
Non-linear analysis of wrinkling phenomena in sandwich beams with soft core
The work is devoted to the local stability analysis of sandwich beams with light core. A linear as well as non-linear numerical analysis is carried out with the use of the finite element method (FEM). Both material and geometrical nonlinearities are taken into account. The goal of the investigation is to examine the influence of the material model on the post-buckling behaviour of a sandwich beam especially on the formation and developing of wrinkles on the compressed face. A pure bending condition is considered for the beam simply supported at both ends. The results for materials of theoretical properties are presented as well as for data from experiments on aluminium sandwich beams. From the results it is seen that the linear analysis of wrinkling phenomenon for non-linear materials gives overestimated results and does not predict correctly the buckling shape.
Copyright (c) 2025 Paweł Jasion, Iwona Małgorzata Wstawska, Kamil Kołodziński https://creativecommons.org/licenses/by/4.0
Sustainable Natural and Synthetic fibers with Epoxy Composites of Mechanical Characterization and One-Way ANOVA Statistical Analysis
It is now well recognized that the combination of natural and synthetic fibers in synergistic fiber composite materials can greatly broaden their applications in engineering and technology. Natural-fibers are gaining more consciousness because of their biodegradability, easy availability, durability, and resistance to corrosion, positioning them as an eco-friendly substitute for conventional materials. At the same time, fiber-reinforced composites are increasingly replacing metals in multiple sectors owing to their cost-effectiveness and energy efficiency. Epoxy resin-based hybrid composites were prepared by incorporating glass, hemp and ramie fibers through the hand layup approch. Laminates were characterized for tensile, flexural, impact, and hardness performance using ASTM standard methods. The greatest tensile strength, 73.10 MPa, was achieved in the glass/ramie fiber composite. The hybrid composites comprising glass, ramie, and hemp fibers exhibited enhanced flexural behavior of 18.22 MPa, impact resistance of 142.45 kJ/m². Among the tested configurations, the glass–ramie fiber composite recorded the highest hardness value of 27.73 HV. Overall, the determination highlight that glass-ramie-hemp fiber-mixed epoxy composite materials can serve as prospective eco-friendly substitute to conventional synthetic composites in non-structural applications, such as automotive interiors, by offering a balance of good mechanical performance and sustainability.
Copyright (c) 2025 Sadashiva Kemparaju, Bhanu Prathap Rangaswamy, Balaji Javaraiah, Shwetha Mahadev, Rathika Murugan, Tarakeshwar Jane https://creativecommons.org/licenses/by/4.0
Preface to a selection of papers presented at the SiMRTRANS Scientific and Technical Conference: “Innovative Solutions in Transport”, which took place at the Warsaw University of Technology, Faculty of Automotive and Construction Machinery Engineering, on September 19, 2024.
SIMRTRANS: Innovative solutions in means of transport
Copyright (c) 2025 Dariusz WIĘCKOWSKI https://creativecommons.org/licenses/by/4.0
Simulation Study of Direct-Shear Test on FRP-to-Concrete Bonded Joints by Means of XFEM
A proper numerical modelling of FRP-to-concrete bonded joints is crucial for determining their strength. In this paper, the results of numerical analyses performed using XFEM on such joints in direct-shear test are presented. The study uses a fracture mechanics approach based on the traction-separation law to define the FRP-concrete interface. It includes the definition of damage initiation as well as damage evolution, taking advantage of the fracture energy of plain concrete as well as the interfacial fracture energy of the analysed joint. The interfacial fracture energy of the bonded joint is essential for accurately describing the local bond–slip behaviour. The numerical study aims to investigate the sensitivity of direct-shear test models to the magnitude of fracture energies, material strengths, the type of adhesive, and the length of FRP-to-concrete joint. Some general results and conclusions of the performed analyses are presented.
Copyright (c) 2025 Iwona Jankowiak https://creativecommons.org/licenses/by/4.0
Machine Learning-Based Welding Defect Recognition Using GLCM Features and k-fold Cross-Validation: KNN and SVM Techniques
Although radiographic inspection is one of the oldest techniques for non-destructive testing, it is still considered vital in many industrial fields to ensure the quality of welds and meet the demands of work conditions and design, as well as safety and reliability requirements. This paper presents an algorithm that identifies and categorizes welding defects in radiographic images using machine learning techniques. For this aim, two supervised classifiers are proposed and performed, which are 1) K-nearest Neighbour (KNN), which is a nonparametric classifier, and 2) a multiclass classifier based on Support Vector Machine (SVM) as an intensive learning-based classifier (enthusiastically learns). SVM is commonly used in binary classification, but it can be adapted for multi-classification using various common methods, such as one-versus-one and one-versus-all. The texture features are adopted in this paper as inputs to the classifiers, where two groups of them are used: the feature of the Local Binary Pattern (LBP) and the grey-level co-occurrence extraction matrix (GLCM), to obtain the feature vector. To avoid the risk of overfitting, four k-fold cross-validations are applied. The experimental results are reported for two different classifiers, achieving an accuracy of 91.66% when combining GLCM and SVM.
Copyright (c) 2026 Sattar J. Kadhim, AbdulBaqi AlSalait, Raheem Al-Sabur, Abdel-Nasser Sharkawy https://creativecommons.org/licenses/by/4.0
A Small-Sample Fault Diagnosis Method for Rolling Bearings Based on Balanced Distribution Adaptation and Support Vector Machine
To address the issue of low diagnostic accuracy caused by distribution differences between source and target domains in rolling bearing fault diagnosis, this study proposes a method combining Balanced Distribution Adaptation (BDA) and Support Vector Machines (SVM). The approach utilizes BDA to simultaneously minimize discrepancies in both edge and conditional distributions between domains, enabling effective feature alignment and enhancing the model's cross-domain generalization in small-sample scenarios. After extracting time and frequency-domain features, BDA adaptively adjusts feature distributions, and SVM is employed for fault classification. Experimental results demonstrate that the BDA-SVM method achieves over 94% diagnostic accuracy, showcasing strong performance and robustness for bearing fault diagnosis. Compared with traditional SVM and other methods without transfer learning, the proposed approach shows significant improvement in diagnostic accuracy under cross-domain conditions.
Copyright (c) 2026 Dong Chen, Mingshan Zhang, Yaguang Gao https://creativecommons.org/licenses/by/4.0
Optimization of Dual-Constrained Grasping Operation of Robotic Arm Based on Optimized Contact Grasping Network
With the continuous improvement of intelligent manufacturing and robot perception capabilities, traditional robotic arm grasping methods still face problems such as inaccurate posture prediction and poor task adaptability in dealing with dynamic scenes, complex objects, and functional action execution. Therefore, the research develops an optimized contact grasping network model that integrates scene constraints and task constraints. It combines UR5 six degree of freedom robotic arm, visual input, and Contact-GraspNet architecture based on point cloud, and introduces PointNet++ local feature enhancement mechanism and lightweight encoder design to effectively improve the spatial perception and action planning capabilities of grasping points. Experimental results show that on the GraspNet and YCB Dataset, the model achieves F1 scores of 92.54% and 91.82% respectively, with average execution time reduced to 0.61 seconds. In functional operation scenarios involving door handles, kettle handles, and drawer pulls, grasping accuracy remained above 0.89, with task completion rates significantly outperforming mainstream baseline models. Under visual interference conditions with up to 75% occlusion rate, the average inference latency was controlled within 0.82 seconds. Under varying light intensities, the pose angle error remained within the range of 1.21° to 1.87°. Therefore, this model exhibits comprehensive advantages in grasping precision, latency control, and deployment efficiency, and has the potential to be largely applied in industrial, service, and special task environments.
Copyright (c) 2026 Feifei Zhao https://creativecommons.org/licenses/by/4.0
Caustics Formation by a Spherical Reflector – Geometric and Wave Field Analysis with Applications in Room Acoustics and Radio Astronomy
Based on the principles of geometrical optics, an analytical description of caustics generated in a spherical mirror is presented. The formation of caustics in a wave field is studied using acoustic and electromagnetic waves as an example. Symmetry of equations describing energy relations in acoustics and electromagnetism is shown. The presence of caustics in natural phenomena is demonstrated, as well as their manifestation in architectural acoustics and astronomy. It is explained why in the sound field in existing halls, rather than the entire caustics, only their cusp is observed, which is perceived as a blurred area with an increased sound level accompanied by unusual values of acoustic room parameters. The influence of caustics on the efficiency of spherical and parabolic antennas used in radio astronomy is discussed.
Copyright (c) 2025 Andrzej Kulowski https://creativecommons.org/licenses/by/4.0
Numerical Modeling of the Aluminum Alloy AW5083 Using Large-Strain Thermo-Elasto-Plasticity
This paper deals with the constitutive modeling and finite element (FE) simulations of advanced models related to large-strain thermo-elasto-plastic behavior of aluminum alloy AW5083, which can reproduce the material response at different temperatures from room temperature up to 500 °C. Significant focus is placed on internal sources of cooling and heating resulting from thermo-elastic and thermo-plastic couplings, respectively, and on the influence of elevated temperature on these couplings. The formulation of the constitutive description is based on a thermodynamic approach. Two models are presented and tested, including temperature-dependent and temperature-independent plastic free energy function. Numerical tests of the developed models are carried out for a uniaxial tensile test. For the sake of comparison with experimental results, a dogbone specimen examined in a tensile machine is analyzed.
Copyright (c) 2025 Agnieszka Sobierańska, Balbina Wcisło https://creativecommons.org/licenses/by/4.0
On the Out-of-Plane Deviation of Bending Deformation States in Moderately Thick Bars with Asymmetric Cross-Sections
A characteristic feature of the six-parameter theories of bars is the coupled form of the constitutive equations; in particular the equations linking transverse forces with transverse shear deformations cannot be, in general, decoupled while keeping a separate form of the remaining constitutive equations. The mentioned feature of the constitutive equations implies that, within the six-parameter theories of straight elastic prismatic bars, there do not exist, in general, plane states of bending/shearing deformations. Thus, any vertical load causes lateral deflections, the only exception being the pure bending problem. The present paper delivers analytical solutions: closed-form formulae for shape functions, i.e., deformation states associated with kinematic loads at the ends, and solutions to selected static problems corresponding to transverse span load. Although elementary, the presented solutions seem to be derived for the first time. In particular, the hitherto published shape functions concerned the theories of moderately thick bars in which all the constitutive equations are decoupled.
Copyright (c) 2026 Radosław Czubacki, Zofia Kozyra, Tomasz Lewiński https://creativecommons.org/licenses/by/4.0
Development of Online Monitoring Device for Ash Accumulation Status of Alkali Recovery Boiler
The alkali recovery boiler is an important piece of equipment in chemical pulp production. It uses papermaking black liquor as fuel. Due to the large number of impurities, the heating surface is prone to severe ash deposition. To improve the heat transfer coefficient, the traditional method is to carry out timed soot blowing, which has problems such as untimely ash cleaning or excessive steam consumption caused by overly frequent soot blowing. In this paper, an experimental device for the relationship between the heat transfer coefficient and the weight of ash deposition was developed. The functional relationship between the two was obtained. There is an inflection point when the amount of ash deposition reaches 294.77 g. A control strategy of soot blowing at the inflection point was further proposed. A load-strain experimental testing device was developed. Experiments show that when the weight of ash deposition reaches 3503 N, the deformation of the suspender is 9 με, and starting the soot blowing device is the most efficient when the heat transfer coefficient is 725.15 W/(m²·K). Therefore, the degree of decline of the heat transfer coefficient can be indirectly reflected by measuring the strain. A method of soot blowing by detecting the degree of suspender strain was further proposed. This method is more scientific than the original timed soot blowing method and provides a technical reference for the energy-saving and consumption-reduction theories and engineering applications of alkali recovery boilers.
Copyright (c) 2026 Bo Wang, Caiming Zhang, Yuanli Wang https://creativecommons.org/licenses/by/4.0
Analysis of a Variable Geometry Radial Inflow Turbine Using 1D Mean-line Model
Despite great progress in 3D computational fluid dynamics (CFD), mathematical modeling used for turbomachinery analysis, the prediction of flow parameters in the rotor (impeller) of radial inflow turbines using existing turbulence models often yields unsatisfactory results. This is because real physical processes related to turbulence are very complex. Other limitations of CFD tools include numerical errors due to finite difference approximations. Thus, for the analysis and optimization of radial inflow turbines, empirical loss correlations applied to a mean-line 1D mathematical model can provide faster and more accurate results compared to CFD simulations. In this study, a 1D approach was used for the mathematical modeling of gas flow in a variable geometry radial inflow turbine with a vaneless volute distributor (VVD). The variable geometry turbine (VGT) was part of a turbocharging system. Combustion engine operation mode with high-power and low-crankshaft rotational speed was chosen, as engine performance under this condition is sensitive to turbocharger adjustment in terms of break specific fuel consumption (BSFC) and other critical parameters. An experimentally-based approach was used where gas flow characteristics in the VGT were calculated under real engine-turbocharger operating conditions. Accordingly, exhaust gas parameters were first measured on an experimental setup. Mathematical modeling then allowed to assess how adjustment in VGT influenced turbine indices, including loss distribution across the stage. It was also validated in this study that during high-load and low-crankshaft operating conditions of the compression ignition (CI) engine, it is recommended to minimize the cross-sectional area at the outlet of the volute acceleration section in the VGT. This adjustment results in better fuel efficiency and lower thermal loads on turbine components, despite a slight reduction in the turbine’s overall efficiency.
Copyright (c) 2025 Dmytro SAMOILENKO https://creativecommons.org/licenses/by/4.0
A Prime-Number/Uniform Angular Distribution Criterion for Blade Vibration Reduction
Currently, the vibration noise of casting cleaning equipment exceeds 95 dB, which not only shortens the equipment’s service life but also jeopardizes workers’ health. The primary cause lies in the resonance tendency resulting from an uneven distribution of blades in the shotblasting device. In this paper, a prime-number/uniform angular distribution criterion and a dynamic balance elimination relationship are established to minimize resonance coupling while accounting for the internal characteristics of the shot-blasting device and blade assembly. Subsequently, a shot-blasting device with seven prime-number angular front-curved blades was designed and fabricated, and the dynamic imbalance caused by uneven blade distribution was compensated for by drilling. We employed the discrete element method to evaluate projectile velocity and stability. The results indicate that the shot velocity reaches a maximum of 75 m/s, with fluctuations within 4 m/s. After reaching 0.24 s, particles accelerated by the shot-blasting device achieve relative stability. Finally, vibration data acquired at a sampling frequency of 10 Ksps demonstrates that noise levels are reduced from 97 dB (traditional structure) to 93.3 dB (new model). This new criterion for shot-blasting machine models mitigates operational vibration while enhancing working conditions and improving overall stability and system reliability.
prime-number/uniform angular distribution criterion
shot-blasting device with seven prime-number angular front-curved blades
Copyright (c) 2025 Yong Li, Yaao Di, Wenzheng Dong, Fangxiang Yin, Yihao Yin, Shanling Han https://creativecommons.org/licenses/by/4.0
Graphical Method for Synthesizing a Four-Bar Linkage with Specified Coupler Angular Reversal Positions
Graphical methods remain an important tool in the theory of mechanisms due to their ability to visually convey fundamental kinematic principles. They are particularly useful in the early design stages and in educational contexts, where intuitive understanding is essential. Among the applications of graphical synthesis methods, mechanisms that require a link to momentarily stop at specific angular positions – commonly referred to as angular reversal positions – are of particular interest. While various analytical and numerical methods exist for designing such mechanisms, they typically focus on dwell positions of rotational or translational links and rely on optimization techniques, often at the cost of geometric transparency. This paper presents a graphical synthesis method for a four-bar linkage designed to achieve two prescribed positions at which the coupler reverses its direction of rotation. This specific problem has not been previously addressed in the literature. It arises in mechanisms used for emptying containers, where the coupler carries the container and must instantaneously pause at two distinct angular positions to ensure stable discharge. Unlike many graphical methods, which may involve ambiguity due to trial-and-error selection of geometric parameters, the proposed technique ensures a unique and geometrically consistent solution while also allowing the Grashof conditions to be satisfied. This contrasts with many numerical methods, where constraint verification is often deferred until the final stages. The construction proposed here is both practically relevant and introduces a novel graphical approach, broadening the scope of synthesis methods to encompass mechanisms exhibiting link dwells in planar motion and reaffirming the relevance of graphical approaches.
Copyright (c) 2026 Jacek Buśkiewicz https://creativecommons.org/licenses/by/4.0
Performance of a Hybrid Ichthyoid-Waterjet Articulated Propulsor
The concept of a bioinspired ichthyoid-waterjet propulsor for autonomous underwater vehicles (AUVs) is investigated. The propulsor consists of an articulated fluid-conveying pipe with a propulsive fin at the end. Water drawn into the hull is accelerated to a supercritical velocity, which yields flutter vibrations of the propulsor resembling the motion of a swimming fish. The fin acts on the surrounding water and generates thrust. At the same time, the ejected water produces recoil. Using the proposed dynamical model, three types of propulsors for different swimming speeds are investigated. At low swimming speeds, the propulsive force generated by the propulsors can be up to 30% higher than the thrust of a conventional waterjet propulsor with the same physical parameters. However, this advantage in the generated thrust decreases with the swimming speed increase. The results are obtained by analyzing the approximation of the bifurcating solution and numerical simulations of the differential equation governing the dynamics.
Copyright (c) 2025 Tomasz SZMIDT https://creativecommons.org/licenses/by/4.0
Analysis of the Braking Process for Curvilinear Motion of Vehicle
Road incident reconstruction frequently includes the possibility of avoiding a collision. To perform such analysis, it is necessary to compare the available distance with the minimum braking distance. Therefore, to avoid a collision, the braking distance must be shorter than the available distance. The braking distance depends on parameters such as tyre-to-road adhesion coefficient, the initial velocity of a vehicle, the driver’s reaction time and the time needed to reach full braking force. However, the problem is that, in practice, none of these values are known during traffic incident reconstruction. As a result, the estimated vehicle velocity is uncertain. This is due to the method used to reconstruct a road incident (and the errors in the evidence data). The tyre-to-road adhesion coefficient depends on many factors and can be estimated with limited accuracy, usually ±0.1. The uncertainty of the estimate is approximately ±15%. The reaction time of a specific driver under the conditions present during a road incident is not precisely known. Therefore, an average value for most drivers is taken into account. It is assumed that a healthy driver’s reaction time should not exceed this value, and a longer reaction time is associated with incorrect driving behavior. The time taken to reach full braking force in a real situation is also unknown. Usually, average values are taken from the literature, without the analysis of a technical condition of a vehicle. This article considers the mechanics of vehicle braking, taking into account the action of lateral forces on this vehicle while considering a curved track. The maximum deceleration during braking is determined analytically, and a condition is formulated to indicate whether it is justified to use an advanced computational model instead of the basic one described in the literature. The analysis includes some dimensionless parameters describing the position of the center of gravity, tangential forces between the tyre and the road, the intensity of turning and braking, suspension characteristics, and asymmetrical mass distribution. This dimensionless approach may be useful for applying the presented analysis of braking on the road arc in accident reconstruction, especially when comparative analysis is recommended.
Copyright (c) 2025 Piotr FUNDOWICZ, Hubert SAR, Mateusz BRUKALSKI, Michał ABRAMOWSKI https://creativecommons.org/licenses/by/4.0
Energy Efficiency of an LPG-Powered Extended-Range Electric Vehicle
This paper deals with energy efficiency evaluation of an extended range electric vehicle (EREV) equipped with a range extender (REX) powered by liquefied petroleum gas (LPG). The investigation is based on simulation, with key input data derived from empirical studies carried out by the authors. It includes four target driving ranges (200, 300, 400, 500 km), six driving cycles (WLTC 3b, FTP-75, CLTC-P, Artemis 130, NYCC, HWFET) and three battery size variants for the WLTC 3b cycle. The influence of the these factors on the overall efficiency and specific energy consumption of the EREV is assessed. The results are analyzed in terms of the number of REX activations per 100 km and the total REX operating time.
Copyright (c) 2025 Paweł KRAWCZYK, Artur KOPCZYŃSKI, Jakub LASOCKI https://creativecommons.org/licenses/by/4.0
On Frequency Dependence of Stability in Materials with Fractional Viscosity
Material instability refers to the tendency of materials to undergo alterations in their properties in loading. The concept of instability is governed by the constitutive equation of solids. Our analysis uses the entire set of equations describing the motion of solids, including the kinematical equation and Cauchy’s equations of motion. Damping, or rate-dependence, plays a crucial role in stability. A potential generalization involves the utilization of fractional-order derivatives of the strain or stress tensors. The stability analysis primarily focuses on periodic perturbations. The mechanism of loss of stability on various parts of the stability boundary is under consideration.
Copyright (c) 2025 Peter B. Béda https://creativecommons.org/licenses/by/4.0
Changes in the Damping Ratio and Energy Transfer Ratio Due to Damage in a Composite Beam
This paper investigates changes in the modal parameters of a composite beam resulting from damage introduced to the bottom flange of a steel I-beam. Variations in the modal damping ratio and energy transfer ratio (ETR) are analysed. The results of experimental tests and numerical analyses are presented. The beam was modelled using the rigid finite elements (RFEs) method. The introduced damage caused small changes in the damping ratio. In contrast, the ETR was found to be more sensitive to damage than the damping ratio in the experimental results, exhibiting variations on the order of several tens of percent. In the numerical simulation results, changes in the ETR were smaller, reaching a few percent.
Copyright (c) 2026 Małgorzata Jarosińska https://creativecommons.org/licenses/by/4.0
Determination of Operating Conditions of a Probe Block Designed for Fault Diagnostics in Rail Heads
In this paper, the key parameters influencing the proper operation of ultrasonic probes for railway rails diagnostics are determined. The goal is to test a set of ultrasonic probes under conditions occurring at high diagnostic speeds. Four issues are studied in more detail. The probe block-rail contact force required to obtain maximum echo level is determined. In the authors’ opinion, the key aspect is the design of the water irrigation nozzle shape in order to produce a laminar couplant flow under the probes. The dependence of the amplitude of the recorded echo on the coupling layer thickness is experimentally investigated. The population of registered signal samples is processed to determine the testing speed limit, which resulted from the loss of data validation ability. The speed limit is calculated based on the average value of the amplitude of the measured signal and the standard deviation of the registered population of amplitudes. The conducted research allows the authors to conclude that the instrumentation they developed enables the recording of an ultrasonic signal propagating through the tested rail at scanning speed of up to 100 km/h.
Copyright (c) 2025 Zbigniew RANACHOWSKI, Sławomir MACKIEWICZ, Tomasz KATZ, Tomasz DĘBOWSKI, Grzegorz STARZYŃSKI, Marcin LEWANDOWSKI, Łukasz ANTOLIK https://creativecommons.org/licenses/by/4.0
The Development Features and Design of a Vibratory Gyroscope with a Metallic Cylindrical Resonator
This paper presents the results of developing a vibratory gyroscope with a cylindrical resonator made of Elinvar alloy. The vibratory gyroscope operates in three modes. These modes include rate mode, rate-integrating mode, and a new, third, differential mode. The differential mode can simultaneously measure two opposite angular rates, Ω and −Ω. A block diagram of the standing wave control system for each mode is presented. The advantages and disadvantages of each of the modes are analyzed. A triple-mode gyro is proposed. The results of experimental studies and simulation data are also presented.
Copyright (c) 2025 Valerii CHIKOVANI, Serhii HOLOVACH, Hryhorii STROKACH, Vadym AVRUTOV https://creativecommons.org/licenses/by/4.0
Multi-Objective Optimization of Hobbing Process Parameters Based on Response Surface Method
In hobbing machining, gear geometric accuracy is an important factor affecting gear working performance, which is determined by the interaction of different process parameters. To improve the geometric accuracy of hobbing surface and obtain the minimum geometric error, this paper adopts the response surface method (RSM) to study the effects of various technological parameters on the geometric accuracy, and explores the influence law of various factors on the geometric accuracy through the response surface diagram. The mathematical models of total profile deviation, total helix deviation, cumulative total deviation of tooth spacing and radial runout were established based on response surface method, and the reliability of the models was tested by variance analysis. Non-dominated sorting whale optimization algorithm (NSWOA) was used to solve the mathematical model, and Pareto solution set was obtained. Entropy weight-TOPSIS method was used to determine the optimal scheme after NSWOA algorithm optimization. After optimization, the total deviation of tooth profile is reduced by 8.04 %, the total deviation of helix is reduced by 9.17 %, the cumulative total deviation of tooth spacing is reduced by 3.88 %, and the radial runout is reduced by 7.45 %, which proves that the optimized scheme can improve the gear accuracy after hobbing machining, and provides a reference for the reasonable selection of gear hobbing process parameters.
Copyright (c) 2025 Yazhou Wang, Xiaohui Yin https://creativecommons.org/licenses/by/4.0
Dynamic Eccentricity Modeling of a Switched Reluctance Motor
The switched reluctance motor (SRM), known for its robust and simple construction, is widely utilized in critical applications. This study investigates the impact of rotor dynamic eccentricity on the motor's current signal. Our research introduces a straightforward diagnostic method to detect and quantify dynamic eccentricity by analyzing the current signal spectrum. This approach specifically focuses on identifying amplitude increases in characteristic additional harmonics, leveraging fundamental electromagnetic transformations to eliminate the need for complex algorithms. Through coupled computer simulations, combining a finite element analysis model (FEMM) with dynamic equation solutions in Simulink, this study identifies specific eccentricity ranges and their corresponding characteristic current values, offering a reliable tool for SRM condition monitoring.
Copyright (c) 2025 Jakub LORENCKI, Adrian CHMIELEWSKI https://creativecommons.org/licenses/by/4.0