Next Issue
Volume 13, February
Previous Issue
Volume 12, December
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
3.0
2.1
Journals
Machines
Volume 13
Issue 1
share announcement

Machines, Volume 13, Issue 1 (January 2025) – 72 articles

Cover Story (view full-size image): The HJ-Haptic, a wearable haptic device, utilizes a honeycomb jamming mechanism to provide real-time kinesthetic feedback for bilateral teleoperation. Weighing only 20 g, the device dynamically adjusts stiffness (1.15–2.64 N/mm) using a vacuum pressure of 30 kPa. Its implementation in a stiffness-rendering teleoperation framework possibly enables operators to adjust grip force based on reliable feedback of remote object stiffness. Experiments, including three-point flexural tests and teleoperated object-grasping tasks, have demonstrated the device’s functionality and its potential to mimic the sensation of direct object manipulation with the hands. The results of this study highlight the possibility of using the honeycomb jamming mechanism to enhance haptic feedback in teleoperation and extended-reality applications. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
17 pages, 8531 KiB  
Article
Milling-Force Prediction Model for 304 Stainless Steel Considering Tool Wear
by Changxu Wang, Yan Li, Feng Gao, Kejun Wu, Kan Yin, Peng He and Yunjiao Xu
Machines 2025, 13(1), 72; https://doi.org/10.3390/machines13010072 - 20 Jan 2025
Viewed by 441
Abstract
The high-performance alloy, 304 stainless steel, is widely used in various industries. However, its material properties lead to severe tool wear during milling processes, significantly increasing milling force and adversely impacting machining quality and efficiency. Consequently, an accurate milling-force model is crucial for [...] Read more.
The high-performance alloy, 304 stainless steel, is widely used in various industries. However, its material properties lead to severe tool wear during milling processes, significantly increasing milling force and adversely impacting machining quality and efficiency. Consequently, an accurate milling-force model is crucial for guiding the formulation and optimization of machining parameters. This paper presents a milling-force prediction model for 304 stainless steel that incorporates the effect of tool wear, based on the mechanistic modeling approach. Side-milling experiments on 304 stainless steel were conducted to analyze the relationship between milling force and tool wear, identify the model coefficients, and validate the prediction accuracy of the milling-force model. The results demonstrate that the model accurately predicts the milling forces of worn tools while side milling 304 stainless steel under various machining parameters and tool wear conditions. Full article
(This article belongs to the Special Issue Advanced Manufacturing and Assembly Technologies for Aerospace Production Systems)
►▼ Show Figures

Figure 1

25 pages, 24599 KiB  
Article
MCBA-MVACGAN: A Novel Fault Diagnosis Method for Rotating Machinery Under Small Sample Conditions
by Wenhan Huang, Xiangfeng Zhang, Hong Jiang, Zhenfa Shao and Yu Bai
Machines 2025, 13(1), 71; https://doi.org/10.3390/machines13010071 - 20 Jan 2025
Viewed by 426
Abstract
In complex industrial scenarios, high-quality fault data of rotating machinery are scarce and costly to collect. Therefore, small sample fault diagnosis needs further research. To solve this problem, in this work is proposed a minimum variance auxiliary classifier generation adversarial network based on [...] Read more.
In complex industrial scenarios, high-quality fault data of rotating machinery are scarce and costly to collect. Therefore, small sample fault diagnosis needs further research. To solve this problem, in this work is proposed a minimum variance auxiliary classifier generation adversarial network based on a multi-scale convolutional block attention mechanism. Firstly, the multi-scale convolutional block attention mechanism is designed to extract multi-scale information and perform weighted fusion to enhance the ability of the model to capture effective features. Secondly, the minimum variance term is designed to minimize the variance of sample distribution, so that the generated samples are distributed more evenly in the feature space, avoiding the problem of pattern collapse. Finally, the objective function is reconstructed by independent classification loss to improve the ability of model data generation. Experimental results on CWRU and gearbox datasets validate the effectiveness and reliability of the proposed method. Full article
(This article belongs to the Section Machines Testing and Maintenance)
►▼ Show Figures

Figure 1

20 pages, 9366 KiB  
Article
Design and Experimental Characterization of Developed Human Knee Joint Exoskeleton Prototypes
by Michał Olinski
Machines 2025, 13(1), 70; https://doi.org/10.3390/machines13010070 - 18 Jan 2025
Viewed by 383
Abstract
This paper focuses on the experimental testing and characterisation of two designed and constructed prototypes of a human knee joint mechanism. The aim of the mechanical systems, presented as kinematic diagrams and 3D CAD drawings, is to reproduce the knee joint’s complex movement, [...] Read more.
This paper focuses on the experimental testing and characterisation of two designed and constructed prototypes of a human knee joint mechanism. The aim of the mechanical systems, presented as kinematic diagrams and 3D CAD drawings, is to reproduce the knee joint’s complex movement, in particular the flexion/extension in the sagittal plane, within a given range and constraints, while taking into account the trajectory of the joint’s instantaneous centre of rotation. The first prototype can simulate different movements by modifying its dimensions in real time using a linearly adjustable crossed four-bar mechanism. The second prototype has interchangeable cooperating components, with cam profiles that can be adapted to specific requirements. Both devices are built from 3D-printed parts and their characteristics are determined experimentally. Although many types of tests have been carried out, this research mainly aims to conduct experiments with volunteers. To this end, the IMU sensors measure the mechanisms’ movements, but the main source of the data is video analysis of the colour markers. For the purposes of postprocessing, the results in the form of numerical values and figures were computed by Matlab 2019b. To illustrate the prototypes’ capabilities, the results are shown as motion trajectories of selected tibia/femur points and the calculated knee joint’s flexion/extension angle. Full article
(This article belongs to the Special Issue Selected Papers from MEDER 2024: Advances of Mechanism Design for Robotic Machines)
►▼ Show Figures

Figure 1

21 pages, 7738 KiB  
Article
High-Accuracy and Efficient Simulation of Numerical Control Machining Using Tri-Level Grid and Envelope Theory
by Zhengwen Nie and Yanzheng Zhao
Machines 2025, 13(1), 69; https://doi.org/10.3390/machines13010069 - 18 Jan 2025
Viewed by 348
Abstract
Virtual simulation of high-resolution multi-axis machining processes nowadays plays an important role in the production of complex parts in various industries. In order to improve the surface quality and productivity, process parameters, such as spindle speed, feedrate, and depth of cut, need to [...] Read more.
Virtual simulation of high-resolution multi-axis machining processes nowadays plays an important role in the production of complex parts in various industries. In order to improve the surface quality and productivity, process parameters, such as spindle speed, feedrate, and depth of cut, need to be optimized by using an accurate process model of milling, which requires both the fast virtual prototyping of machined part geometry for tool path verification and accurate determination of cutter–workpiece engagement for cutting force predictions. Under these circumstances, this paper presents an effective volumetric method that can accurately provide the required geometric information with high and stable computational efficiency under the condition of high grid resolution. The proposed method is built on a tri-level grid, which applies two levels of adaptive refinement in space decomposition to abolish the adverse effect of a large fine-level branching factor on its efficiency. Since hierarchical space decomposition is used, this multi-level representation enables the batch processing of affected voxels and minimal intersection calculations, achieving fast and accurate modeling results. To calculate the instantaneous engagement region, the immersion angles are obtained by fusing the intersection points between the bottom-level voxel edges and the cutter surface, which are then trimmed by feasible contact arcs determined using envelope theory. In a series of test cases, the proposed method shows higher efficiency than the tri-dexel model and stronger applicability in high-precision machining than the two-level grid. Full article
(This article belongs to the Section Advanced Manufacturing)
►▼ Show Figures

Figure 1

32 pages, 11857 KiB  
Article
A Hybrid Dynamic Principal Component Analysis Feature Extraction Method to Identify Piston Pin Wear for Binary Classifier Modeling
by Hao Yang, Yubin Zhai, Mengkun Zheng, Tan Wang, Dongliang Guo, Jianhui Liang, Xincheng Li, Xianliang Liu, Mingtao Jia and Rui Zhang
Machines 2025, 13(1), 68; https://doi.org/10.3390/machines13010068 - 18 Jan 2025
Viewed by 320
Abstract
The wear condition of a piston pin is a main factor in determining the operational continuity and life cycle of a diesel engine; identifying its vibration feature is of paramount importance in carrying out necessary maintenance in the early wear stage. As the [...] Read more.
The wear condition of a piston pin is a main factor in determining the operational continuity and life cycle of a diesel engine; identifying its vibration feature is of paramount importance in carrying out necessary maintenance in the early wear stage. As the dynamic vibration features are susceptible to environmental disturbance during operation, an effective signal processing method is necessary to improve the accuracy and fineness of the extracted features, which is essential to build a reliable and precise binary classifier model to identify piston pin wear based on the features. Aiming at the feature extraction requirements of anti-noise, accuracy and effectiveness, this paper proposes a piston pin wear feature extraction algorithm based on dynamic principal component analysis (DPCA) combined with variational mode decomposition (VMD) and singular value decomposition (SVD). An orthogonal sensor layout is applied to collect the vibration signal under normal and worn piston pin conditions, which proved effective in reducing environmental vibration disturbance. DPCA is utilized to extract dynamical vibration features by introducing time lag. Then, the dynamic principal component matrix is further decomposed by VMD to obtain intrinsic mode functions (IMFs) as finer features and is finally decomposed by SVD to compress the features, thus improving the classification efficiency based on the features. To validate the significance of the features extracted by the proposed method, a support vector machine (SVM) is employed to model binary classifiers to evaluate the classification performance trained by different features. A modeling dataset containing 80 samples (40 normal samples and 40 worn samples) is employed, and five-round cross-validation is adopted. For each round, two binary classifier models are trained by features extracted by the proposed method and the empirical mode decomposition (EMD)–auto regressive (AR) spectrum method, fast Fourier transform (FFT) and continuous wavelet transform (CWT), respectively; the classification precision, recall ratio, accuracy and F1 ratio are obtained on the testing set by contrasting the overall performances of the five-round cross-validation, and the proposed method is proved to be more effective in noise reduction and significant feature extraction, which is able to improve the accuracy and efficiency of binary classification for piston pin wear identification. Full article
(This article belongs to the Section Machines Testing and Maintenance)
►▼ Show Figures

Figure 1

17 pages, 5107 KiB  
Article
Design Techniques for the Optimal Creation of a Robot for Interaction with Children with Autism Spectrum Disorder
by Cristofer Tamaral, Lidia Hernandez, Clara Baltasar and Jose San Martin
Machines 2025, 13(1), 67; https://doi.org/10.3390/machines13010067 - 17 Jan 2025
Viewed by 413
Abstract
Educational robotics is a sector that is being integrated into classrooms to achieve innovative and effective learning in the early stages of children’s education. However, it is not only applied in education but has great importance in its use with children with special [...] Read more.
Educational robotics is a sector that is being integrated into classrooms to achieve innovative and effective learning in the early stages of children’s education. However, it is not only applied in education but has great importance in its use with children with special needs to improve their quality of life. The convenience of robots applied to interaction with children with autism spectrum disorder (ASD) has been widely demonstrated. In this work, a study is carried out on what design patterns a robot focused on children with autism should have. It is necessary to make known the characteristics of this and, from there, how to apply these concepts to the effective design of a device. A robot, TEA-2, is proposed that encompasses all these guidelines in a single robot. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
►▼ Show Figures

Figure 1

23 pages, 6485 KiB  
Review
Power Transmission Mechanism and Tribological Performance of Modern Bicycle Drivetrains—A Review
by Yook Wah Liew, Owen Matthews, Dzung Viet Dao and Huaizhong Li
Machines 2025, 13(1), 66; https://doi.org/10.3390/machines13010066 - 17 Jan 2025
Viewed by 435
Abstract
Bicycles are one of the most sustainable forms of transportation and sports available today, known for their environmental friendliness, cost-effectiveness, lightweight design, compactness, and health benefits. The efficiency and power transmission of bicycle drivetrains have emerged as crucial concerns for engineers, bicycle manufacturers, [...] Read more.
Bicycles are one of the most sustainable forms of transportation and sports available today, known for their environmental friendliness, cost-effectiveness, lightweight design, compactness, and health benefits. The efficiency and power transmission of bicycle drivetrains have emerged as crucial concerns for engineers, bicycle manufacturers, and both professional and amateur cyclists. However, research and publications related to bicycle drivetrain systems and their tribological performance are notably limited. There is a lack of systematic reviews on technological progress and recent research works in this field. This paper aims to redress this imbalance by presenting a comprehensive literature review of power transmission and tribology in bicycle drivetrains through assessing an extensive body of theoretical and practical work encompassing bicycle drivetrains and roller chain drive mechanisms and performance. This review comprises an exploration of bicycle drivetrain mechanisms and components, an examination of subjects related to power transmission mechanics and efficiency, and a thorough analysis of tribological factors in bicycle drivetrains, including friction, wear, and lubrication. A particular focus has been put on the performance of roller chain drives. This review consolidates research findings related to power transmission within the bicycle drivetrain systems and outlines some future perspectives in relevant research. Through this review, we aim to shed light on the existing knowledge gaps within bicycle drivetrain research and offer constructive recommendations for advancements in this field. Full article
(This article belongs to the Special Issue Advancements in Mechanical Power Transmission and Its Elements)
►▼ Show Figures

Figure 1

20 pages, 8714 KiB  
Article
Optimization of Toolpath Planning and CNC Machine Performance in Time-Efficient Machining
by Arbnor Pajaziti, Orlat Tafilaj, Afrim Gjelaj and Besart Berisha
Machines 2025, 13(1), 65; https://doi.org/10.3390/machines13010065 - 17 Jan 2025
Viewed by 666
Abstract
This study explores the optimization of the machining time in CNC milling machines by varying the machine parameters and toolpath strategies. Using the ICAM3D simulation software version 3.1.0, this approach focuses on minimizing the machining time while adhering to operational constraints. In addition, [...] Read more.
This study explores the optimization of the machining time in CNC milling machines by varying the machine parameters and toolpath strategies. Using the ICAM3D simulation software version 3.1.0, this approach focuses on minimizing the machining time while adhering to operational constraints. In addition, a novel approach to the optimization of the G-code in time machining, focusing on reducing the machining time while maintaining the required precision and quality of the finished product, is presented. We propose a method that integrates advanced algorithms to identify and eliminate redundant movements, optimize the toolpaths, and improve the machining strategies. The experimental results demonstrate a significant reduction in the machining time without compromising the machining accuracy, offering substantial cost savings and efficiency improvements for industrial applications. The importance of this work lies in the correct choice of the toolpath strategy. In the P3 project, the optimization process reduced the machining time from 15 min and 23 s to 13 min and 33 s by utilizing the optimized G-code. The initial machining time of 20 min and 2 s corresponds to the completion of the P3 project when the CNC machine was operated at 75% speed. To further enhance efficiency, additional software tools such as ARTCAM and ASPIRE have been utilized to implement a new toolpath strategy. Full article
(This article belongs to the Special Issue Innovative Manufacturing Engineering 2024—Processes, Machines, Tooling and Systems Integration)
►▼ Show Figures

Figure 1

17 pages, 37474 KiB  
Article
The Deformation Mechanism of the Rings of Angular-Contact Ball Bearings During the Quenching and Tempering Process
by Ruijie Gu, Yi Tong, Qiang Wang, Liaoyuan Chen and Ziyang Shang
Machines 2025, 13(1), 64; https://doi.org/10.3390/machines13010064 - 17 Jan 2025
Viewed by 361
Abstract
During the heat treatment process, bearing rings are subjected to drastic temperature variability and complex microstructural evolution, which result in deformation, high residual stresses, operational instability and a limited operating life. However, the underlying relationship between temperature, phase transformation, and deformation has not [...] Read more.
During the heat treatment process, bearing rings are subjected to drastic temperature variability and complex microstructural evolution, which result in deformation, high residual stresses, operational instability and a limited operating life. However, the underlying relationship between temperature, phase transformation, and deformation has not been fully revealed in previous research. As a result, it is difficult to accurately control the roundness of bearing rings during the heat treatment process. Therefore, a combination of numerical simulations and experimental methods was employed to analyze the heat treatment process of the rings of angular-contact ball bearings (ACBB) (7008C). Firstly, according to the multiple coupling theory of thermal, phase-transition, and stress–strain fields, a model for the numerical simulation of the quenching and tempering process was established. Secondly, the thermal–physical properties of the material were calculated using the Jmatpro 7.0 software, and the quenching and tempering processes were numerically simulated using the Deform software. Subsequently, the evolution of the stress, phase-transformation, and deformation behaviors of bearing rings during the quenching and tempering were studied in detail. Finally, the roundness errors of the bearing rings were obtained by a coordinate-measuring machine (CMM). The results showed that the axial and radial stress distributions at the surface and center of the bearing rings were significantly different. The bearing rings experienced uneven expansion and deformation. The roundness errors of the inner diameter and outer diameter of the inner ring were 0.0386 mm and 0.0423 mm, respectively. The roundness errors of the inner diameter and outer diameter of the outer ring were 0.0202 mm and 0.0180 mm, respectively. In this study, the mechanism of the effect of the temperature variation and phase transformation on deformation during the quenching and tempering process was revealed in detail. This provides a reference for controlling the roundness of bearing rings in actual production processes. Full article
(This article belongs to the Section Material Processing Technology)
►▼ Show Figures

Figure 1

24 pages, 1574 KiB  
Article
Optimizing Lightweight Material Selection in Automotive Engineering: A Hybrid Methodology Incorporating Ashby’s Method and VIKOR Analysis
by Edoardo Risaliti, Francesco Del Pero, Gabriele Arcidiacono and Paolo Citti
Machines 2025, 13(1), 63; https://doi.org/10.3390/machines13010063 - 16 Jan 2025
Viewed by 411
Abstract
The automotive industry is responsible for about 20% of greenhouse gas emissions in Europe, and it is under notable pressure to meet the reduction targets set by the European Union for the next decades. In this context, lightweighting is a very effective design [...] Read more.
The automotive industry is responsible for about 20% of greenhouse gas emissions in Europe, and it is under notable pressure to meet the reduction targets set by the European Union for the next decades. In this context, lightweighting is a very effective design strategy for which materials selection plays a key role. One of the main challenges of lightweighting is selecting materials with enhanced structural properties but a reduced weight in comparison with traditional solutions. The spectrum of available materials is very large, and the choice needs to be carefully evaluated based on multiple factors, such as mechanical behavior, raw materials cost, the availability of manufacturing processes, and environmental impact. This article presents an innovative methodology for materials selection in the lightweight automotive field based on the Ashby approach for mechanical performance coefficients as an initial filtering criterion. Following this preliminary screening, this study adopts the VIKOR (Vise Kriterijumska Optimizacija I Kompromisno Resenje) MCDA (Multi-Criteria Decision Analysis) technique to rank feasible design solutions based on case study boundary conditions. The evaluation criterion of different design options encompasses crucial factors, such as mechanical properties, cost considerations, and environmental impact measures. The method is finally validated by the application of a redesign case study, a motor bracket of an electric commercial car. Full article
(This article belongs to the Special Issue Design Methods for Mechanical and Industrial Innovation)
►▼ Show Figures

Figure 1

37 pages, 7617 KiB  
Review
The Integration of Additive Manufacturing into Industry 4.0 and Industry 5.0: A Bibliometric Analysis (Trends, Opportunities, and Challenges)
by Shayan Dehghan, Sasan Sattarpanah Karganroudi, Saïd Echchakoui and Noureddine Barka
Machines 2025, 13(1), 62; https://doi.org/10.3390/machines13010062 - 16 Jan 2025
Viewed by 678
Abstract
This bibliographic analysis explores the evolving landscape of additive manufacturing (AM) in the context of Industry 4.0 and the emerging paradigms of Industry 5.0. This research critically examines the key literature and scholarly works to clarify the evolution, challenges, and opportunities presented by [...] Read more.
This bibliographic analysis explores the evolving landscape of additive manufacturing (AM) in the context of Industry 4.0 and the emerging paradigms of Industry 5.0. This research critically examines the key literature and scholarly works to clarify the evolution, challenges, and opportunities presented by integrating AM technologies with digital transformation and advanced industrial practices. The exploration begins by tracing the foundational concepts of Industry 4.0, emphasizing the role of cyber–physical systems, data analytics, and automation in reshaping manufacturing ecosystems. It then moves to the developments of Industry 5.0, focusing on human-centric approaches, collaborative robotics, and sustainable manufacturing strategies that extend beyond automation. The impact of AM technologies across various sectors, from aerospace and automotive industries to healthcare and consumer goods, is central to this analysis. This article synthesizes empirical studies, case analyses, and theoretical frameworks to discern the synergies, challenges, and prospects of integrating AM into Industry 4.0 and the evolving Industry 5.0. Through this bibliographic journey, readers gain insights into the transformative potential of AM as a catalyst for innovation, agility, and sustainability in the digital age. The findings underscore the need for interdisciplinary collaborations, policy frameworks, and technological advancements to harness AM’s full potential within Industry 4.0 and 5.0. Full article
(This article belongs to the Section Industrial Systems)
►▼ Show Figures

Figure 1

28 pages, 11467 KiB  
Article
Design Guidelines for Fractional Order Cascade Control in DC Motors: A Computational Analysis on Pairing Speed and Current Loop Orders Using Oustaloup’s Recursive Method
by Marta Haro-Larrode and Alvaro Gomez-Jarreta
Machines 2025, 13(1), 61; https://doi.org/10.3390/machines13010061 - 16 Jan 2025
Viewed by 389
Abstract
Nested, or cascade speed and torque control has been widely used for DC motors over recent decades. Simultaneously, fractional-order control schemes have emerged, offering additional degrees of control. However, adopting fractional-order controllers, particularly in cascade schemes, does not inherently guarantee better performance. Poorly [...] Read more.
Nested, or cascade speed and torque control has been widely used for DC motors over recent decades. Simultaneously, fractional-order control schemes have emerged, offering additional degrees of control. However, adopting fractional-order controllers, particularly in cascade schemes, does not inherently guarantee better performance. Poorly paired fractional exponents for inner and outer PI controllers can worsen the DC motor’s behavior and controllability. Finding appropriate combinations of fractional exponents is therefore crucial to minimize experimental costs and achieve better dynamic response compared to integer-order cascade control. Additionally, mitigating adverse couplings between speed and current loops remains an underexplored area in fractional-order control design. This paper develops a computational model for fractional-order cascade control of DC motor speed (external) and current (internal) loops to derive appropriate combinations of internal and external fractional orders. Key metrics such as overshoot, rise time, and peak current values during speed and torque changes are analyzed, along with coupled variables like speed drop during torque steps and peak torque during speed steps. The proposed maps guide the selection of effective combinations, enabling readers to deduce robust or adaptive designs depending on specific performance needs. The methodology employs Oustaloup’s recursive approximation to model fractional-order elements, with MATLAB–SIMULINK simulations validating the proposed criteria. Full article
(This article belongs to the Section Electrical Machines and Drives)
►▼ Show Figures

Figure 1

25 pages, 4614 KiB  
Article
Transfer Learning-Based Health Monitoring of Robotic Rotate Vector Reducer Under Variable Working Conditions
by Muhammad Umar Elahi, Izaz Raouf, Salman Khalid, Faraz Ahmad and Heung Soo Kim
Machines 2025, 13(1), 60; https://doi.org/10.3390/machines13010060 - 16 Jan 2025
Viewed by 524
Abstract
Due to their precision, compact size, and high torque transfer, Rotate vector (RV) reducers are becoming more popular in industrial robots. However, repetitive operations and varying speed conditions mean that these components are prone to mechanical failure. Therefore, it is important to develop [...] Read more.
Due to their precision, compact size, and high torque transfer, Rotate vector (RV) reducers are becoming more popular in industrial robots. However, repetitive operations and varying speed conditions mean that these components are prone to mechanical failure. Therefore, it is important to develop effective health monitoring (HM) strategies. Traditional approaches for HM, including those using vibration and acoustic emission sensors, encounter such challenges as noise interference, data inconsistency, and high computational costs. Deep learning-based techniques, which use current electrical data embedded within industrial robots, address these issues, offering a more efficient solution. This research provides transfer learning (TL) models for the HM of RV reducers, which eliminate the need to train models from scratch. Fine-tuning pre-trained architectures on operational data for the three different reducers of health conditions, which are healthy, faulty, and faulty aged, improves fault classification across different motion profiles and variable speed conditions. Four TL models, EfficientNet, MobileNet, GoogleNet, and ResNET50v2, are considered. The classification accuracy and generalization capabilities of the suggested models were assessed across diverse circumstances, including low speed, high speed, and speed fluctuations. Compared to the other models, the proposed EfficientNet model showed the most promising results, achieving a testing accuracy and an F1-score of 98.33% each, which makes it best suited for the HM of robotic reducers. Full article
(This article belongs to the Section Industrial Systems)
►▼ Show Figures

Figure 1

16 pages, 3706 KiB  
Article
Development of a Web-Based e-Portal for Freeform Surfaced Lens Design and Manufacturing and Its Implementation Perspectives
by Shangkuan Liu, Kai Cheng and Negin Dianat
Machines 2025, 13(1), 59; https://doi.org/10.3390/machines13010059 - 16 Jan 2025
Viewed by 340
Abstract
In modern freeform surfaced optics manufacturing, ultraprecision machining through single-point diamond turning (SPDT) plays a crucial role due to its ability to meet the high accuracy demands of optical design and stringent surface quality requirements of the final optic. The process involves meticulous [...] Read more.
In modern freeform surfaced optics manufacturing, ultraprecision machining through single-point diamond turning (SPDT) plays a crucial role due to its ability to meet the high accuracy demands of optical design and stringent surface quality requirements of the final optic. The process involves meticulous steps, including optic surface modeling and analysis, optic design, machining toolpath generation, and manufacturing. This paper presents an integrated approach to customized precision design and the manufacturing of freeform surfaced varifocal lenses through a web-based e-portal. The approach implements an e-portal-driven manufacturing system that seamlessly integrates lens design, modeling and analysis, toolpath generation for ultraprecision machining, mass personalized customization, and service delivery. The e-portal is specifically designed to meet the stringent demands of personalized mass customization, and to offer a highly interactive and transparent experience for the lens users. By using Shiny and R-script programming for platform development and combining COMSOL Multiphysics for the ray tracing simulation, the e-portal leverages open-source technologies to provide manufacturing service agility, responsiveness, and accessibility. Furthermore, the integration of R-script and Shiny programming allows for advanced interactive information processing, which also enables the e-portal-driven manufacturing system to be well suited for personalized complex products such as freeform surfaced lenses. Full article
(This article belongs to the Special Issue Innovative Manufacturing Engineering 2024—Processes, Machines, Tooling and Systems Integration)
►▼ Show Figures

Figure 1

19 pages, 2858 KiB  
Article
RDF Knowledge Graphs Designed with Axiomatic Methodology to Enhance Industry 4.0
by Fernando Rolli, Chiara Parretti, Riccardo Barbieri, Alessandro Polidoro and Bianca Bindi
Machines 2025, 13(1), 58; https://doi.org/10.3390/machines13010058 - 16 Jan 2025
Viewed by 440
Abstract
Industry 4.0 has introduced a data-driven model of production and management of goods and services. This manufacturing paradigm leverages the potential of the Internet of Things (IoT), but finding the information necessary to drive manufacturing processes can be challenging. In this context, the [...] Read more.
Industry 4.0 has introduced a data-driven model of production and management of goods and services. This manufacturing paradigm leverages the potential of the Internet of Things (IoT), but finding the information necessary to drive manufacturing processes can be challenging. In this context, the authors propose an innovative approach based on axiomatic design to design RDF knowledge graphs from which to extract the information needed by decision makers. This approach derives from the possibility of providing RDF knowledge graphs with an equivalent matrix representation based on axiomatic design. It allows the selection of the most reliable data sources, thereby optimizing the knowledge graph construction process using matrix algebra, minimizing redundancy and improving the efficiency of query response. The goal of the presented methodology is to address the five critical aspects of Big Data (volume, velocity, variety, value, and veracity) by preordering the knowledge graph according to the information needs of business decision makers, thereby optimizing the use of the immense wealth of information made available by the Web in design. Full article
(This article belongs to the Special Issue Design Methods for Mechanical and Industrial Innovation)
►▼ Show Figures

Figure 1

17 pages, 926 KiB  
Article
State of Change-Related Hybrid Energy Storage System Integration in Fuzzy Sliding Mode Load Frequency Control Power System with Electric Vehicles
by Yuzhe Xie, Peng Liao, Zhihao Liang and Dan Zhou
Machines 2025, 13(1), 57; https://doi.org/10.3390/machines13010057 - 16 Jan 2025
Viewed by 370
Abstract
In the context of the integration of hybrid energy storage systems (HESSs) and electric vehicles (EVs), this paper investigates the load frequency control (LFC) issue of the power system. Weighting coefficients are set for the generators, HESSs and EVs, respectively, to show their [...] Read more.
In the context of the integration of hybrid energy storage systems (HESSs) and electric vehicles (EVs), this paper investigates the load frequency control (LFC) issue of the power system. Weighting coefficients are set for the generators, HESSs and EVs, respectively, to show their different abilities to regulate the power system. A fuzzy logic-based sliding mode control approach is designed to ensure the stable performance of the LFC power system integrated with HESSs and EVs. The improvement of the proposed method is the application of the linear matrix inequality (LMI) toolbox in fuzzy controller design, which solves the limitations and uncertainties caused by trial-error or experience in common fuzzy controllers. There is no general form for the membership function of the fuzzy control. This paper presents a design approach for the membership function based on the calculation results of LMI. Simulations are tested on an IEEE 39-bus system integrated with HESSs and EVs. The simulation results prove that the proposed method reduces the time required for the power system frequency to reach stability by approximately 8.8%, demonstrating the superiority and usability of the proposed approach. Full article
(This article belongs to the Special Issue Advanced Battery Management Technology in Electric Vehicles: Present Status and Future Trends)
►▼ Show Figures

Figure 1

19 pages, 6972 KiB  
Article
Development of an Innovative Magnetorheological Gearbox for Positioning Control and Anti-Disturbance of a Robotic Arm
by Yuyang Zhang, Shuaishuai Sun, Lei Deng, Guorui Wang, Rui Yu, Weihua Li, Xinglong Gong, Shiwu Zhang, Haiping Du and Jian Yang
Machines 2025, 13(1), 56; https://doi.org/10.3390/machines13010056 - 15 Jan 2025
Viewed by 424
Abstract
The robotic arm is a critical component of modern industrial manufacturing. However, its positioning performance can be hindered by overshooting and oscillation. External disturbances, including collisions or impacts with other objects, can also affect its accuracy and precision. To resolve this problem, this [...] Read more.
The robotic arm is a critical component of modern industrial manufacturing. However, its positioning performance can be hindered by overshooting and oscillation. External disturbances, including collisions or impacts with other objects, can also affect its accuracy and precision. To resolve this problem, this work integrates a compact magnetorheological (MR) bearing, which is capable of switching between locking and unlocking states utilizing the MR effect, into the gearbox of the actuation system of the robotic arm. This integration enables the gearbox (referred to as the MR gearbox) to exhibit variable damping characteristics. This controllable damping property will play an important role in improving the positioning accuracy by offering additional damping. In this study, the MR gearbox was first designed and prototyped. A characterization test was then conducted to verify its variable damping property. The classic Bouc–Wen model was used to describe the MR gearbox and then a mathematical model was established for the whole robotic arm. Additionally, a new variable damping control method was proposed for further improving the positioning precision and reducing energy consumption. As follows, the positioning and the anti-disturbance performances of the robotic arm system installed with the MR gearbox were assessed through numerical simulations and experimental tests. The result shows that the robotic arm under the new control method achieves reductions of 11.76% in overshoot, 14.73% in settling time, and 26.1% in energy consumption compared to the uncontrolled case under the step trajectory, indicating improved positioning performance. Full article
(This article belongs to the Special Issue Adaptive Control Using Magnetorheological Technology)
►▼ Show Figures

Figure 1

22 pages, 6604 KiB  
Review
Application of Soft Grippers in the Field of Agricultural Harvesting: A Review
by Daode Zhang, Wei Zhang, Hualin Yang and Haibing Yang
Machines 2025, 13(1), 55; https://doi.org/10.3390/machines13010055 - 14 Jan 2025
Viewed by 494
Abstract
This review summarizes the important properties required for applying soft grippers to agricultural harvesting, focusing on their actuation methods and structural types. The purpose of the review is to address the challenges of limited load capacity and stiffness, which significantly hinder the broader [...] Read more.
This review summarizes the important properties required for applying soft grippers to agricultural harvesting, focusing on their actuation methods and structural types. The purpose of the review is to address the challenges of limited load capacity and stiffness, which significantly hinder the broader application of soft grippers in agriculture. This paper examines the research progress on variable stiffness methods for soft grippers over the past five years. We categorize various variable stiffness techniques and analyze their advantages and disadvantages in enhancing load capacity, stiffness, dexterity, degree of integration, responsiveness, and energy consumption of soft grippers. The applicability and limitations of these techniques in the context of agricultural harvesting are also discussed. This paper concludes that combined material variable stiffness technology with a motor actuation claw structure in soft grippers is better suited for agricultural harvesting operations of woody crops (e.g., apples, citrus) and herbaceous crops (e.g., tomatoes, cucumbers) in unstructured environments. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
►▼ Show Figures

Figure 1

20 pages, 7847 KiB  
Article
Performance Analysis of a Waste-Gated Turbine for Automotive Engines: An Experimental and Numerical Study
by Carla Cordalonga, Silvia Marelli and Vittorio Usai
Machines 2025, 13(1), 54; https://doi.org/10.3390/machines13010054 - 13 Jan 2025
Viewed by 454
Abstract
In this article, the results of an experimental investigation and a 1D modeling activity on the steady-state performance of a wastegated turbocharger turbine for spark ignition engines are presented. An experimental campaign to analyze the turbine performance for different waste-gate valve openings was [...] Read more.
In this article, the results of an experimental investigation and a 1D modeling activity on the steady-state performance of a wastegated turbocharger turbine for spark ignition engines are presented. An experimental campaign to analyze the turbine performance for different waste-gate valve openings was conducted at the test bench for components of propulsion systems of the University of Genoa. Thanks to the experimental activity, a 1D model is developed to assess the interaction between the flow through the impeller and the by-pass port. Advanced modeling techniques are crucial for improving the assessment of turbocharger turbines performance and, consequently, enhancing the engine–turbocharger matching calculation. The initial tuning of the model is based on turbine characteristic maps obtained with the by-pass port kept closed. The study then highlights the waste-gate valve behavior considering its different openings. It was found that a more refined model is necessary to accurately define the mass flow rate through the waste-gate valve. After independently tuning the 1D models of the turbine and the waste-gate valve, their behavior is analyzed in parallel-flow conditions. The results highlight significant interactions between the two components that must be taken into account to reduce inaccuracies in the engine-turbocharger matching calculation. These interactions lead to a reduced swallowing capacity of the turbine impeller. This reduction has an impact on the power delivered to the compressor, the boost pressure, and, consequently, the engine backpressure. The results suggest that methods generally adopted that consider the by-pass valve and the turbine as two nozzles working in parallel under the same thermodynamic condition could be insufficient to accurately assess the turbocharger behavior. Full article
(This article belongs to the Special Issue Cutting-Edge Mobility Solutions for High Efficiency Propulsion Systems)
►▼ Show Figures

Figure 1

24 pages, 9386 KiB  
Article
Finite Element Research of Cup Wheel Grinding Heat Based on Trochoid Scratch Model
by Pengcheng Zhao, Bin Lin, Jingguo Zhou, Bingrui Lv and Tianyi Sui
Machines 2025, 13(1), 53; https://doi.org/10.3390/machines13010053 - 13 Jan 2025
Viewed by 418
Abstract
Grinding is a highly precise machining process. However, excessive temperatures during grinding can result in adverse thermal effects on the machined material. In this study, cup wheel grinding was analyzed using a model that represents heat generation as a trochoid discrete heat source [...] Read more.
Grinding is a highly precise machining process. However, excessive temperatures during grinding can result in adverse thermal effects on the machined material. In this study, cup wheel grinding was analyzed using a model that represents heat generation as a trochoid discrete heat source formed by the interactions between abrasive particles and the workpiece surface. With this approach, certain assumptions were made to facilitate analysis, including the modeling of abrasive grains as rigid point heat sources. Finite element simulations and experimental validations based on the trochoid model were conducted using COMSOL 6.2 software. These analyses evaluated the thermal behavior of cup wheel grinding under varying wheel speeds and feed rate ratios. The results revealed an asymmetrical distribution of the temperature field in cup wheel grinding. By examining both surface and subsurface temperature fields, this study provided a more comprehensive understanding of grinding heat. Furthermore, this investigation explored the influence of trochoid trajectories and process parameters on the temperature field, highlighting intersection and curvature thermal effects. These findings contribute valuable analytical methods and theoretical insights for controlling grinding heat in precision machining processes. Full article
(This article belongs to the Section Machine Design and Theory)
►▼ Show Figures

Figure 1

19 pages, 6477 KiB  
Article
Numerical Investigation and Experimental Verification of Vibration Behavior for a Beam with Cantilever-Hertzian Contact Boundary Conditions
by Yinnan Zhang, Chao Zhang, Yuan Meng and Wanbin Ren
Machines 2025, 13(1), 52; https://doi.org/10.3390/machines13010052 - 13 Jan 2025
Viewed by 360
Abstract
The simple spring structure, with detachable electrical contacts, is a very suitable solution for many applications, such as electromechanical relays and connectors. However, they are prone to exhibit instantaneous interruption faults under mechanical vibration environments. In this paper, the governing equations of the [...] Read more.
The simple spring structure, with detachable electrical contacts, is a very suitable solution for many applications, such as electromechanical relays and connectors. However, they are prone to exhibit instantaneous interruption faults under mechanical vibration environments. In this paper, the governing equations of the modal analysis of a beam with cantilever-Hertzian contact boundary conditions are presented. Then, the time domain analysis method and frequency domain analysis method for solving the forced vibration response are described explicitly. Next, the effect of the axial force on the modal frequency of a detailed model sourced from the practical relay is investigated by using commercial ANSYS Workbench 2021R1 software. Afterward, the harmonic response of the beam is numerically solved individually by using the transient analysis model and the harmonic analysis model in ANSYS Workbench 2021R1 software. Then, the influences of the damping coefficient and excited frequency on the contact force response are investigated. The experimental results of transient displacement and contact resistance of the beam structure agree well with the simulation outcomes. It is proven that there is a linear relationship between the stiffness coefficient and the mass coefficient, which are used for characterizing the damping of the structures in the time domain method and frequency domain methods. Full article
(This article belongs to the Section Machine Design and Theory)
►▼ Show Figures

Figure 1

19 pages, 9423 KiB  
Article
A Common DC Bus Circulating Current Suppression Method for Motor Emulators of New Energy Vehicles
by Haonan Sun, Dafang Wang, Qi Li and Yingkang Qin
Machines 2025, 13(1), 51; https://doi.org/10.3390/machines13010051 - 13 Jan 2025
Viewed by 401
Abstract
In contrast to the conventional topology, wherein the Device Under Test (DUT) controller and the electric motor emulator (EME) are powered by the DC (Direct Current) voltage source independently, the common DC bus topology necessitates a single power supply. This reduces the cost [...] Read more.
In contrast to the conventional topology, wherein the Device Under Test (DUT) controller and the electric motor emulator (EME) are powered by the DC (Direct Current) voltage source independently, the common DC bus topology necessitates a single power supply. This reduces the cost and complexity of the motor emulator system, making it more favorable for large-scale industrial applications. However, this topology introduces significant circulating current issues in the system. A common DC bus circulating current suppression method is proposed in this paper for the motor emulator. First, the mechanism of zero-sequence circulating current generation in the common DC bus topology is analyzed and the expression for the system’s zero-sequence voltage difference is derived. Then, a control method based on a Hybrid PWM (Pulse Width Modulation) strategy that unifies SPWM (SIN Pulse Width Modulation) and SVPWM (Space Vector Pulse Width Modulation) is proposed, which has been shown to be effective in suppressing the zero-sequence circulating current in a motor emulator system with a common DC bus topology. The proposed control method has been experimentally validated using a motor emulator system. Full article
(This article belongs to the Special Issue New Trends in Reliability and Lifetime Improvement in Power-Electronic-Controlled Machines and Devices)
►▼ Show Figures

Figure 1

31 pages, 21587 KiB  
Article
Bearing Fault Feature Extraction Method Based on Adaptive Time-Varying Filtering Empirical Mode Decomposition and Singular Value Decomposition Denoising
by Xuezhuang E, Wenbo Wang and Hao Yuan
Machines 2025, 13(1), 50; https://doi.org/10.3390/machines13010050 - 13 Jan 2025
Viewed by 400
Abstract
Aiming to address the difficulty in extracting the early weak fault features of bearings under complex operating conditions, a fault diagnosis method is proposed based on the adaptive fusion of time-varying filtering empirical mode decomposition (TVF-EMD) modal components and singular value decomposition (SVD) [...] Read more.
Aiming to address the difficulty in extracting the early weak fault features of bearings under complex operating conditions, a fault diagnosis method is proposed based on the adaptive fusion of time-varying filtering empirical mode decomposition (TVF-EMD) modal components and singular value decomposition (SVD) noise reduction. First, the snake optimization (SO) technique is used to optimize the TVF-EMD algorithm in order to determine the optimal parameters that match the input signal. Then, the bearing signal is divided into a number of intrinsic mode functions (IMFs) using TVF-EMD in order to reduce the nonlinearity and non-stationary characteristics of the fault signal. An index for the envelope fault information energy ratio (EFIER) is created to overcome the drawback of there being too many IMF components after TVF-EMD decomposition. The IMF components are ranked in descending order according to the EFIER, and they are fused according to the maximum principle of the energy ratio of envelope fault information until the optimal fusion component is determined. Finally, the fault feature is extracted when the optimal fusion component is denoised using SVD. Two measured bearing fault signals and simulation signals are used to validate the performance of the proposed method. The experimental findings demonstrate that the approach has good sensitive feature screening, fusion, and noise reduction capabilities. The proposed method can more precisely extract the early fault features of bearings and accurately identify fault types. Full article
(This article belongs to the Section Machines Testing and Maintenance)
►▼ Show Figures

Figure 1

21 pages, 2363 KiB  
Article
Smart Defect Detection in Aero-Engines: Evaluating Transfer Learning with VGG19 and Data-Efficient Image Transformer Models
by Samira Mohammadi, Vahid Rahmanian, Sasan Sattarpanah Karganroudi and Mehdi Adda
Machines 2025, 13(1), 49; https://doi.org/10.3390/machines13010049 - 13 Jan 2025
Viewed by 516
Abstract
This study explores the impact of transfer learning on enhancing deep learning models for detecting defects in aero-engine components. We focused on metrics such as accuracy, precision, recall, and loss to compare the performance of models VGG19 and DeiT (data-efficient image transformer). RandomSearchCV [...] Read more.
This study explores the impact of transfer learning on enhancing deep learning models for detecting defects in aero-engine components. We focused on metrics such as accuracy, precision, recall, and loss to compare the performance of models VGG19 and DeiT (data-efficient image transformer). RandomSearchCV was used for hyperparameter optimization, and we selectively froze some layers during training to help better tailor the models to our dataset. We conclude that the difference in performance across all metrics can be attributed to the adoption of the transformer-based architecture by the DeiT model as it does this well in capturing complex patterns in data. This research demonstrates that transformer models hold promise for improving the accuracy and efficiency of defect detection within the aerospace industry, which will, in turn, contribute to cleaner and more sustainable aviation activities. Full article
(This article belongs to the Section Machines Testing and Maintenance)
►▼ Show Figures

Figure 1

18 pages, 3398 KiB  
Article
Investigation of Factors Influencing Solenoid Valve Speed Response Characteristics of the Common Rail Injector
by Yun Bai, Chengda Du, Qiang Sun, Shi Bu and Ao Wang
Machines 2025, 13(1), 48; https://doi.org/10.3390/machines13010048 - 13 Jan 2025
Viewed by 394
Abstract
The dynamic injection characteristics of high-pressure common rail fuel injection systems are determined by the speed response performance of the solenoid valve. A simulation model has been established for investigating the influence mechanism and change law of characteristic parameters on speed response characteristics [...] Read more.
The dynamic injection characteristics of high-pressure common rail fuel injection systems are determined by the speed response performance of the solenoid valve. A simulation model has been established for investigating the influence mechanism and change law of characteristic parameters on speed response characteristics of the solenoid valve. The speed response characteristics of the solenoid valve, including the average opening speed, the average closing speed, the maximum opening speed, and the maximum closing speed, caused by the changes of characteristic parameters such as pre-tightening force of the solenoid valve spring, mass of the solenoid valve moving parts, diameter of the outflow orifice, diameter of the inflow orifice, diameter of the control piston, and pressure in the common rail, have been studied. The correlation analysis of the influence factors is carried out by using the experimental design method based on the response surface model, and the correlation coefficients between each factor and the speed response characteristics of the solenoid valve are obtained. The results show that both single factors and interaction factors of the parameters are correlated with the speed response characteristics of the solenoid valve. The results of this paper can provide a theoretical reference for the design and optimization of the high-pressure common rail injector. Full article
(This article belongs to the Section Vehicle Engineering)
►▼ Show Figures

Figure 1

27 pages, 9517 KiB  
Article
Semi-Active Suspension Design for an In-Wheel-Motor-Driven Electric Vehicle Using a Dynamic Vibration-Absorbing Structure and PID-Controlled Magnetorheological Damper
by Kyle Samaroo, Abdul Waheed Awan and Sheikh Islam
Machines 2025, 13(1), 47; https://doi.org/10.3390/machines13010047 - 11 Jan 2025
Viewed by 482
Abstract
The in-wheel motor (IWM) powertrain layout offers greater design flexibility and higher efficiency of an electric vehicle but has limited commercial success mainly due to the concerns of increased unsprung mass. This paper proposes a semi-active suspension system for in-wheel motors that combines [...] Read more.
The in-wheel motor (IWM) powertrain layout offers greater design flexibility and higher efficiency of an electric vehicle but has limited commercial success mainly due to the concerns of increased unsprung mass. This paper proposes a semi-active suspension system for in-wheel motors that combines both a dynamic vibration-absorbing structure (DVAS) and a PID-controlled MR damper, in order to achieve optimised comfort, handling and IWM vibration for a small car application. Whilst PID control and DVAS are not entirely new concepts, the usage of both optimisation techniques in a semi-active in-wheel motor suspension has seen limited implementation, which makes the current work novel and significant. The semi-active suspension operating both in passive fail-safe mode and full feedback control was compared to a conventional in-wheel motor passive suspension in terms of sprung mass acceleration, displacement, stator acceleration, tyre deflection and suspension travel for three different road profile inputs using MATLAB/Simulink. The implementation of a PID-controlled MR damper improved road comfort and road holding performance and decreased in-wheel motor vibration over the DVAS passive suspension mainly in terms of a maximum peak amplitude decrease of 40%, 35% and 32% for the sprung mass acceleration, tyre deflection and stator acceleration, respectively. The results are significant since they show that the use of a simple, easily implemented control scheme like PID control was able to significantly improve IWM suspension performance when paired with a DVAS. This study provides further confidence to manufacturers to commercially develop and implement the IWM layout as its major disadvantage can be reasonably addressed using a simple readily available control approach. Full article
(This article belongs to the Special Issue Semi-Active Vibration Control: Strategies and Applications)
►▼ Show Figures

Figure 1

17 pages, 337 KiB  
Article
Linear Matrix Inequalities in Fault Detection Filter Design for Linear Ostensible Metzler Systems
by Dušan Krokavec and Anna Filasová
Machines 2025, 13(1), 46; https://doi.org/10.3390/machines13010046 - 10 Jan 2025
Viewed by 365
Abstract
The article deals with the properties of fault detection filters when applying their structure to a class of linear, continuous-time systems, with dynamics being specified by the system matrix of the ostensible Metzler structure. The proposed solution is reduced to the use of [...] Read more.
The article deals with the properties of fault detection filters when applying their structure to a class of linear, continuous-time systems, with dynamics being specified by the system matrix of the ostensible Metzler structure. The proposed solution is reduced to the use of diagonal stabilization in the synthesis of the state observer and uses the decomposition of the ostensible Metzler matrix. The approach creates a unified framework that covers the compactness of parametric constraints on Metzler matrices and their quadratic stability. Due to the complexity of such constraints, the design conditions are formulated using sharp linear matrix inequalities. For potential application in network control structures, the problem is formulated and solved for linear discrete-time ostensible positive systems. Finally, a linearized model of the B747-100/200 aircraft is used to validate the proposed method. The numerical solution and simulation results show that the proposed approach provides superior sensitivity of the fault detection filter in detecting faults, compared to synthesis methods that do not guarantee the positivity of the filter gain. Full article
(This article belongs to the Special Issue Selected Papers from the 8th International Conference on Control, Automation and Diagnosis (ICCAD 2024))
►▼ Show Figures

Figure 1

16 pages, 3625 KiB  
Article
Influence of Plastic Deformation on the Precipitation Evolution in the Aluminum Alloys in Friction Stir Welding
by Iuliia Morozova, Anton Naumov, Nikolay Doynov and Vesselin Michailov
Machines 2025, 13(1), 45; https://doi.org/10.3390/machines13010045 - 10 Jan 2025
Viewed by 310
Abstract
The influence of temperature on the precipitation evolution in different zones of friction stir welded (FSW) heat-treatable aluminum alloys has been well investigated. However, the role of plastic deformation in affecting precipitation transformations remains less explored. To isolate the contribution of these factors [...] Read more.
The influence of temperature on the precipitation evolution in different zones of friction stir welded (FSW) heat-treatable aluminum alloys has been well investigated. However, the role of plastic deformation in affecting precipitation transformations remains less explored. To isolate the contribution of these factors and specifically assess the role of plastic deformation, an approach combining numerical and physical modeling techniques was used. Welding temperature cycles in the FSW weld zones calculated by means of a 3D finite element model were accurately reproduced using a Gleeble instrument. This approach was implemented under two scenarios such as the reproduction of the influence of temperature alone, and the combined effects of temperature and thermally induced plastic strain. The precipitation states and hardness obtained from these controlled experiments were compared to those observed in actual friction stir welds, providing a deeper understanding of the influence mechanisms at play. The results revealed that deformation significantly influences precipitation formation in the stir zone of both 2024 and 6082 alloys, with this effect extending to the heat-affected zone in the case of the 2024 alloy. Full article
(This article belongs to the Special Issue Novel Manufacturing Processes and Their Innovation for Industries)
►▼ Show Figures

Figure 1

21 pages, 11416 KiB  
Article
Research into the Possibilities of Improving the Adhesion Properties of a Locomotive
by Vadym Ishchuk, Kateryna Kravchenko, Miroslav Blatnický, Alyona Lovska and Ján Dižo
Machines 2025, 13(1), 44; https://doi.org/10.3390/machines13010044 - 10 Jan 2025
Viewed by 349
Abstract
Locomotives are important vehicles, which serve for towing wagons, i.e., trains. Many factors influence the safe and cost-effective operation of locomotives and trains in general. One of these factors is adhesion at the wheel/rail contact. The adhesion determines how much power the locomotive [...] Read more.
Locomotives are important vehicles, which serve for towing wagons, i.e., trains. Many factors influence the safe and cost-effective operation of locomotives and trains in general. One of these factors is adhesion at the wheel/rail contact. The adhesion determines how much power the locomotive can deliver and how the braking system will ensure that the train stops. The main way to improve adhesion is to use sand at the wheel/rail contact point. The aim of this study is to improve the efficiency of the sand system of the locomotive. For this purpose, a new sand system nozzle mounting design was proposed. The newly proposed sanding system is equipped with a nozzle mounted to the axlebox unlike the original one, which uses the nozzle attached to the bogie frame. To compare the proposed and existing design, simulation calculations were performed in Simpack software 2024.3. For the simulation computation of the locomotive bogie, two types of railway tracks were chosen. A straight track section with two angular frequencies and three amplitudes of track irregularities was created, and a real track section corresponding to several kilometers of track was modeled in the Simpack software. During the simulations, it was determined that the proposed nozzle mounting design has a smaller amplitude of motion, compared to the existing one; therefore, there is a more accurate and efficient operation of the sand system. This in turn has a favorable effect on the adhesion of the wheel with the rail. It was found out that the newly designed sanding system has a significant positive economic effect regarding saving sand. There is no sand loss during sandblasting compared with the original sanding system. This directly relates to saving costs during locomotive operation. Full article
(This article belongs to the Special Issue Research and Application of Rail Vehicle Technology)
►▼ Show Figures

Figure 1

29 pages, 11146 KiB  
Article
Stage-Based Remaining Useful Life Prediction for Bearings Using GNN and Correlation-Driven Feature Extraction
by Guangzhong Huang, Wenping Lei, Xinmin Dong, Dongliang Zou, Shijin Chen and Xing Dong
Machines 2025, 13(1), 43; https://doi.org/10.3390/machines13010043 - 10 Jan 2025
Viewed by 379
Abstract
Bearings are critical components in mechanical systems, and their degradation process typically exhibits distinct stages, making stage-based remaining useful life (RUL) prediction highly valuable. This paper presents a model that combines correlation analysis feature extraction with a Graph Neural Network (GNN)-based approach for [...] Read more.
Bearings are critical components in mechanical systems, and their degradation process typically exhibits distinct stages, making stage-based remaining useful life (RUL) prediction highly valuable. This paper presents a model that combines correlation analysis feature extraction with a Graph Neural Network (GNN)-based approach for bearing degradation stage classification and RUL prediction, aiming to achieve accurate bearing life prediction. First, the proposed Pearson–Spearman correlation metric, along with Kernel Principal Component Analysis (KPCA) and autoencoders, is used to group and fuse health indicators (HIs), thereby obtaining a health indicator (HI) that effectively reflects the bearing degradation process. Then, a model combining Graph Convolutional Network (GCN) and Long Short-Term Memory (LSTM) networks is proposed for bearing degradation stage classification. Based on the classification results, the Adaptive Attention GraphSAGE–LSTM (AAGL) model, also introduced in this study, is employed to precisely predict the bearing’s remaining useful life. Full article
(This article belongs to the Section Machines Testing and Maintenance)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-72
Previous Issue
Next Issue
Back to TopTop