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14 pages, 1854 KiB  
Article
Design and Optimization of a Piezoelectric Stick-Slip Actuator with Distributed Compliance
by Tingting Ye, Zhao Feng and Yangmin Li
Machines 2025, 13(6), 460; https://doi.org/10.3390/machines13060460 - 27 May 2025
Viewed by 186
Abstract
With increasing demand for high-precision motion control systems, high operational speed and load capacity are imposed with piezoelectric stick-slip actuators based on compliant mechanisms, yet their performances are often constrained by the step size and move speed. In this paper, a novel piezoelectric [...] Read more.
With increasing demand for high-precision motion control systems, high operational speed and load capacity are imposed with piezoelectric stick-slip actuators based on compliant mechanisms, yet their performances are often constrained by the step size and move speed. In this paper, a novel piezoelectric stick-slip actuator featuring flexure beams and a trapezoidal driving foot is proposed for high dynamic performance and load requirements. The trapezoidal structure consists of a trapezoidal driving foot to differentiate the friction in the stick and slip phases, four flexure beams for the high resonant frequency due to distributed compliance and the high load capacity due to structural geometry, and a rigid rod for motion transmission. At first, the mechanism design and the working principle are described in detail. Then, its dominant performances are predicted through finite element analysis, including the step size and the first natural frequency. On this basis, the structural parameters are optimized through the genetic algorithm. As a result, the forward displacement in the stick phase can be obtained as 4.8 μm through FEA simulations, where the first natural frequency can be observed as 627 Hz. Full article
(This article belongs to the Special Issue Optimization and Design of Compliant Mechanisms)
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34 pages, 16960 KiB  
Article
Hollow-Type Integrated Assembly Design and Performance Validation of Conductive Slip Rings via Simulation-Driven Optimization
by Zhiyuan Qian, Chao Han, Nianhuan Li, Gongqiang Tian, Junye Li and Haihong Wu
Machines 2025, 13(5), 415; https://doi.org/10.3390/machines13050415 - 15 May 2025
Viewed by 200
Abstract
Conductive slip rings (CSRs) are precision components critical to industrial equipment, yet they face challenges such as unstable signal transmission, limited functionality, and difficulties in operational monitoring due to assembly-induced inaccuracies. This study proposes a hollow-type integrated assembly solution, incorporating optimized transmission, clamping, [...] Read more.
Conductive slip rings (CSRs) are precision components critical to industrial equipment, yet they face challenges such as unstable signal transmission, limited functionality, and difficulties in operational monitoring due to assembly-induced inaccuracies. This study proposes a hollow-type integrated assembly solution, incorporating optimized transmission, clamping, and protection modules through structural design and modular analysis. Static and dynamic simulations identify the optimal assembly angle and connector configuration (hollow-type outperforming flange-type), ensuring reliability and stability. A high-precision universal assembly platform is designed, and an R-axis rotary table-based testing method is developed to evaluate transmission and fixation modes. Results demonstrate the superiority of sleeve couplings and hollow connectors, with the assembled system achieving contact resistance fluctuations below 10 mΩ, angular repeatability under 500″, and accuracy within 720″, meeting all design specifications. The proposed framework combines simulation-driven design with experimental validation, offering a robust approach to enhance the performance of CSRs in industrial applications. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
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18 pages, 5103 KiB  
Article
Elastic Wave Propagation Through Cylinders with Fluid-Filled Fractures Using the Discontinuous Galerkin Method
by Ana L. Ramos-Barreto, Jonas D. De Basabe and Raul U. Silva-Avalos
Mathematics 2025, 13(10), 1572; https://doi.org/10.3390/math13101572 - 10 May 2025
Viewed by 259
Abstract
Accurately modeling fractures in wave-propagation simulations is challenging due to their small scale relative to other features. While equivalent-media models can approximate fracture-induced anisotropy, they fail to capture their discrete influence on wave propagation. To address this limitation, the Interior-Penalty Discontinuous Galerkin Method [...] Read more.
Accurately modeling fractures in wave-propagation simulations is challenging due to their small scale relative to other features. While equivalent-media models can approximate fracture-induced anisotropy, they fail to capture their discrete influence on wave propagation. To address this limitation, the Interior-Penalty Discontinuous Galerkin Method (IP-DGM) can be adapted to incorporate the Linear-Slip Model (LSM) to represent fractures explicitly. In this study, we apply IP-DGM to elastic wave propagation in fractured cylindrical domains using realistic fracture compliances obtained from laboratory experiments (using ultrasonic-pulse transmission) to simulate the effects of fluid-filled fractures. We analyze how fracture spacing and fluid type influence P- and S-wave behavior, focusing on amplitude attenuation and wave-front delays. Our numerical results align with experimental and theoretical predictions, demonstrating that higher-density fluids enhance wave transmission, reducing the impedance contrast and improving coupling across fracture surfaces. These findings highlight the capability of IP-DGM to accurately model wave propagation in realistic fractured and saturated media, providing a valuable tool for seismic monitoring in fractured reservoirs and other applications where fluid-filled fractures are prevalent. Full article
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18 pages, 8811 KiB  
Article
Lightweight Ti3VNbAl0.5Zrx (x = 0, 0.1, 0.5, and 1) Refractory High-Entropy Alloys with an Optimized Balance of Strength and Ductility
by Haoyu Fang, Xuejiao Wang, Aidong Lan, Xi Jin and Junwei Qiao
Metals 2025, 15(5), 503; https://doi.org/10.3390/met15050503 - 30 Apr 2025
Viewed by 210
Abstract
Achieving a balance between strength and room-temperature ductility remains an urgent need and a significant challenge for body-centered cubic (BCC) structure materials. In this paper, a good combination of strength and ductility in single-phase BCC-structured Ti3VNbAl0.5Zrx (x = [...] Read more.
Achieving a balance between strength and room-temperature ductility remains an urgent need and a significant challenge for body-centered cubic (BCC) structure materials. In this paper, a good combination of strength and ductility in single-phase BCC-structured Ti3VNbAl0.5Zrx (x = 0, 0.1, 0.5, and 1) lightweight high-entropy alloys (LHEAs) was designed by reducing the valence-electron concentration in combination with the d-electron theory. The influences of Zr on the microstructures and mechanical properties of the alloys were systematically studied. The yield strengths of Zr0, Zr0.1, Zr0.5, and Zr1 alloys were 644 MPa, 703 MPa, 827 MPa, and 904 Mpa, respectively. The tensile strains of Zr0, Zr0.1, Zr0.5, and Zr1 alloys were 29%, 30%, 20%, and 16%, respectively. The deformation mechanism was studied using transmission electron microscopy (TEM). The results demonstrate that the alloys could still maintain single-phase BCC structure after deformation, and neither phase transformation nor twinning was detected during the deformation process. The main deformation mechanism of the Zr1 alloy is dislocation slip. The current work has great significance for developing high-strength, ductile, and low-density structural materials. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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14 pages, 10839 KiB  
Article
Microstructural Stability and Creep Behavior of a Re/Ru Single-Crystal Nickel-Based Alloy
by Ning Tian
Crystals 2025, 15(4), 370; https://doi.org/10.3390/cryst15040370 - 17 Apr 2025
Viewed by 208
Abstract
By testing the creep properties of a Re/Ru-containing single-crystal alloy specimen and examining the microstructural evolution of the allow at different stages of creep using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the deformation and damage mechanisms of the alloy under [...] Read more.
By testing the creep properties of a Re/Ru-containing single-crystal alloy specimen and examining the microstructural evolution of the allow at different stages of creep using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the deformation and damage mechanisms of the alloy under ultra-high temperature conditions were investigated. It was observed that a dislocation network forms before the rafting of the γ′ phase. As creep progresses, this network becomes increasingly dense and complete. Moreover, the dislocation network undergoes a transformation from the <110>-type to the <100>-type configuration, with a hybrid <110>-<100>-type network representing an intermediate state during the transition. Stacking faults were also identified within the γ′ phase, suggesting that the stacking fault energy of this alloy is lower compared to that of other alloys. During creep, dislocations that penetrate the γ′ phase can undergo cross slip from the {111} plane to the {100} plane under applied stress, resulting in the formation of Kear–Wilsdorf (K–W) immobile dislocation locks. These locks hinder further dislocation movement within the γ′ phase. It is concluded that the damage mechanism of the alloy at the later stage of creep under 120 MPa/1160 °C involves initial crack formation at the interface of the twisted raft-like γ/γ′ two-phase structure. As creep continues, the crack propagates in a direction perpendicular to the applied stress axis. Full article
(This article belongs to the Special Issue Microstructure and Mechanical Properties of Alloys and Composites)
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14 pages, 17104 KiB  
Article
Rope on Rope: Reducing Residual Vibrations in Rope-Based Anchoring System and Rope-Driven Façade Operation Robot
by Kangyub Lee, Sahoon Ahn, Jeongmo Yang, Hwasoo Kim and Taewon Seo
Sensors 2025, 25(8), 2463; https://doi.org/10.3390/s25082463 - 14 Apr 2025
Viewed by 321
Abstract
Maintenance of the exteriors of buildings with convex façades, such as skyscrapers, is in high demand in urban centers. However, manual maintenance is inherently dangerous due to the possibility of accidental falls. Therefore, research has been conducted on cleaning robots as a replacement [...] Read more.
Maintenance of the exteriors of buildings with convex façades, such as skyscrapers, is in high demand in urban centers. However, manual maintenance is inherently dangerous due to the possibility of accidental falls. Therefore, research has been conducted on cleaning robots as a replacement for human workers, e.g., the dual ascension robot (DAR), which is an underactuated rope-driven robot, and the rope-riding mobile anchor (RMA), which is a rope-riding robot. These robots are equipped with a convex-façade-cleaning system. The DAR and RMA are connected to each other by a rope that enables vibration transmission between them. It also increases the instability of the residual vibration that occurs during the operation of the DAR. This study focused on reducing the residual vibrations of a DAR to improve the stability of the overall system. Because it is a rope-on-rope (ROR) system, we assumed it to be a simplified serial spring–damper system and analyzed its kinematics and dynamics. An input-shaping technique was applied to control the residual vibrations in the DAR. We also applied a disturbance observer to mitigate factors contributing to the system uncertainty, such as rope deformation, slip, and external forces. We experimentally validated the system and assessed the effectiveness of the control method, which consisted of the input shaper and disturbance observer. Consequently, the residual vibrations were reduced. Full article
(This article belongs to the Special Issue Intelligent Service Robot Based on Sensors Technology)
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16 pages, 4156 KiB  
Article
Flow Management in High-Viscosity Oil–Gas Mixing Systems: A Study of Flow Regimes
by Jiaming Tian, Mao Li and Yueshe Wang
Energies 2025, 18(6), 1550; https://doi.org/10.3390/en18061550 - 20 Mar 2025
Viewed by 335
Abstract
The flow management of the gas–liquid mixture module is crucial for the transmission efficiency of crude oil-and-natural gas-gathering and transportation systems. The concurrent flow of high-viscosity crude oil and natural gas in gas–liquid mixing is investigated numerically by adopting an improved volume of [...] Read more.
The flow management of the gas–liquid mixture module is crucial for the transmission efficiency of crude oil-and-natural gas-gathering and transportation systems. The concurrent flow of high-viscosity crude oil and natural gas in gas–liquid mixing is investigated numerically by adopting an improved volume of fluid (VOF) model programmed with the OpenFOAM v2012 software package. Over a wide range of superficial velocities for the oil, from 0.166 to 5.529 m/s, and natural gas, from 0.138 to 27.645 m/s, a variety of flow regimes of bubble flow, plug flow, slug flow, and annular flow are encountered successively, which are essentially consistent with the Brill and Mandhane flow regime identification criteria. The results show that the oil volume fraction, fluid velocity, and bubble slip velocity together affect the growth of bubbles in the pipeline at a low gas velocity. In the case of slug flow, the phenomenon of liquid film plugging is noticeable, and the flow is very unstable, which should be avoided as much as possible. Nonetheless, it is commended that stable plug flow and annular flow with a high oil transportation efficiency and minimal power consumption are friendly working conditions. Full article
(This article belongs to the Section H: Geo-Energy)
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15 pages, 8614 KiB  
Article
Microstructural Modification by Large Pre-Deformation and Post-Aging to Improve Properties in Al-Mg-Li Alloy
by Zeyu Zheng, Peipei Ma, Longhui Chen and Chunhui Liu
Metals 2025, 15(3), 290; https://doi.org/10.3390/met15030290 - 6 Mar 2025
Cited by 1 | Viewed by 744
Abstract
Al-Mg-Li alloy is an ideal lightweight structural material for aerospace applications due to its low density, high specific strength, and excellent low-temperature performance. This study examines the mechanical properties and microstructural evolution of Al-Mg-Li alloy subjected to cryogenic and room temperature cold rolling, [...] Read more.
Al-Mg-Li alloy is an ideal lightweight structural material for aerospace applications due to its low density, high specific strength, and excellent low-temperature performance. This study examines the mechanical properties and microstructural evolution of Al-Mg-Li alloy subjected to cryogenic and room temperature cold rolling, which induces large plastic deformation. Compared with room temperature rolling, cryogenic rolling significantly reduces surface cavity formation, thereby enhancing the alloy’s rolling surface quality. After cryogenic rolling by 80% and subsequent natural aging, the yield strength of artificially aged Al-Mg-Li alloy reaches 560 MPa, delivering a 60% increase compared to the traditional T6 state with a slight reduction in elongation from 6.5% to 4.6%. The specific strength achieves 2.23 × 105 N·m/kg, outperforming conventional Al-Cu-Li and 7xxx-series Al alloys. The depth of intergranular corrosion decreases from 100 µm to 10 µm, demonstrating excellent corrosion resistance enabled by the new method. Transmission electron microscopy reveals that finely distributed δ′ (Al3Li) is the primary strengthening phase, with high-density dislocations further enhancing strength. However, coarsening of δ′ (from ~2.9 nm to >6 nm) induced by ensuing artificial aging results in coplanar slip and reduced elongation. Lowering the post-aging temperature inhibits δ′ coarsening, thereby improving both strength and elongation. Our results provide valuable insights into optimizing the properties of Al-Mg-Li alloys for advanced lightweight applications. Full article
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20 pages, 3107 KiB  
Article
Processing and Characterisation of Alumina/Eucryptite Nanostructured Composites
by Jordana Mariot Inocente, Renata Bochanoski da Costa, Ana Sônia Mattos, Carmen Alcázar, Amparo Borrell, Rodrigo Moreno, Sabrina Arcaro and Oscar Rubem Klegues Montedo
Materials 2025, 18(3), 671; https://doi.org/10.3390/ma18030671 - 3 Feb 2025
Viewed by 690
Abstract
Alumina is one of the most studied and used ceramic materials, but increasing its fracture toughness is still a challenge for many specific impact applications. Adding a second phase with a low coefficient of thermal expansion (CTE) to an alumina matrix can enhance [...] Read more.
Alumina is one of the most studied and used ceramic materials, but increasing its fracture toughness is still a challenge for many specific impact applications. Adding a second phase with a low coefficient of thermal expansion (CTE) to an alumina matrix can enhance the matrix’s mechanical properties, reduce its sintering temperature, and increase its toughness by generating compressive stresses on the alumina particle surface. In this study, nanostructured alumina/eucryptite composites were prepared to achieve enhanced toughness. First, eucryptite (Li2O·Al2O3·2SiO2) nanoparticles were successfully synthesised via colloidal heterocoagulation. These nanoparticles were then used to reinforce alumina matrices through slip casting followed by conventional sintering. Complete crystallisation of eucryptite was achieved at 850 °C with a CTE of 0.46 × 10 −6 °C ¹. Transmission electron microscopy analysis revealed that the average particle size was 28.5 ± 14.5 nm. To achieve a relative density of 95.3%, the composite containing 5 vol.% eucryptite required sintering for 1 h at 1400 °C whereas pure alumina required 2 h at 1600 °C. This reduction in sintering temperature (by up to 200 °C) helped to improve the fracture toughness, with the alumina grain size decreasing from 2.3 to 0.9 µm. The advantages of the new composite are the more economically viable and environmentally friendly way of producing the lithium aluminosilicate nanoparticles, compared to the production of ceramic frits at high temperatures (~1500 °C). Full article
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12 pages, 7227 KiB  
Article
Dislocation Transformations at the Common 30°⟨0001⟩ Grain Boundaries During Plastic Deformation in Magnesium
by Yulong Zhu, Yaowu Sun, An Huang, Fangxi Wang and Peng Chen
Nanomaterials 2025, 15(3), 232; https://doi.org/10.3390/nano15030232 - 31 Jan 2025
Viewed by 894
Abstract
After the thermal-mechanical processing of Mg alloys, extensive 30°⟨0001⟩ grain boundaries (GBs) are present in the recrystallized structure, which strongly affects the mechanical properties via interactions with lattice dislocations. In this work, we systematically investigate how the 30°⟨0001⟩ GBs influence the slip transmission [...] Read more.
After the thermal-mechanical processing of Mg alloys, extensive 30°⟨0001⟩ grain boundaries (GBs) are present in the recrystallized structure, which strongly affects the mechanical properties via interactions with lattice dislocations. In this work, we systematically investigate how the 30°⟨0001⟩ GBs influence the slip transmission during plastic deformation. We reveal that basal dislocations can be transmuted into its neighboring grain and continue gliding on the basal plane. The prismatic dislocation can transmit the GB remaining on the same Burgers vector. However, a mobile pyramidal c+a dislocation can be absorbed at GBs, initiating the formation of new grain. These findings provide a comprehensive understanding on GB-dislocation interaction in hexagonal close-packed (HCP) metals. Full article
(This article belongs to the Special Issue Mechanical Properties and Applications for Nanostructured Alloys)
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16 pages, 12609 KiB  
Article
Microstructure and Micro-Mechanical Properties of Thermally Sprayed HA-TiO2 Coating on Beta-Titanium Substrate
by Abdulaziz Kurdi, Doaa Almalki, Ahmed Degnah and Animesh Kumar Basak
Materials 2025, 18(3), 540; https://doi.org/10.3390/ma18030540 - 24 Jan 2025
Viewed by 836
Abstract
Metallic biomaterials in a solid form cause stress-shielding in orthopedic applications. Such implants also suffer from limited tissue attachment to become a part of the living system. In view of that, hydroxyapatite (HA) coating reinforced with titanium oxide (TiO2) was deposited [...] Read more.
Metallic biomaterials in a solid form cause stress-shielding in orthopedic applications. Such implants also suffer from limited tissue attachment to become a part of the living system. In view of that, hydroxyapatite (HA) coating reinforced with titanium oxide (TiO2) was deposited in a beta (β)-Titanium (Ti-35Nb-7Ta-5Zr) substrate by plasma spray. This allows us to exploit the best of the two materials, namely the relatively low modulus of β-Ti, together with the porous and bone-like structure/composition of the HA to facilitate cell growth. This is foreseen to be used as an implant, particularly for musculoskeletal-related disability. Detailed scanning electron microscopy (SEM) investigation shows the lamellar structure of the coating that is composed of different phases and some porosities. Transmission electron microscopy (TEM) confirms the co-existence of both the amorphous and crystalline phases that build up the coating structure. In situ micro-mechanical tests revealed that the HA-TiO2 coating was low in strength and modules compared to that of the substrate material, together with lower ductility. The yield stress and modulus of elasticity of the coating were about 877 ± 174 MPa and 447 ± 24 MPa, respectively. In contrast, the beta (β)-Ti substrate possesses about 990 ± 85 MPa of yield stress and 259 ± 19 MPa modulus of elasticity. The deformation mechanism was also quite different, where the coating crumbled under compressive loading, featuring limited ductility with cleavage (brittle)-type fracture, and the substrate showed plastic flow of materials in the form of slip/shear planes with extended ductility. Full article
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17 pages, 14616 KiB  
Article
A Noise-Tolerant Carrier Phase Recovery Method for Inter-Satellite Coherent Optical Communications
by Chunyuan Hu, Yujie Lin, Zihao Wu, Ruolin Yang and Xiangyuan Bu
Electronics 2025, 14(2), 265; https://doi.org/10.3390/electronics14020265 - 10 Jan 2025
Cited by 1 | Viewed by 859
Abstract
Coherent free-space optical communication offers significant advantages in terms of communication capacity, making it particularly suitable for high-speed inter-satellite transmission within satellite communication networks. Nonetheless, the presence of Doppler frequency offset (FO) and phase noise (PN) associated with lasers adversely affects the bit [...] Read more.
Coherent free-space optical communication offers significant advantages in terms of communication capacity, making it particularly suitable for high-speed inter-satellite transmission within satellite communication networks. Nonetheless, the presence of Doppler frequency offset (FO) and phase noise (PN) associated with lasers adversely affects the bit error rate (BER) performance of these communication systems. Conventional methods for FO and phase estimation are usually hindered by high computational demands and phase cycle slips, especially in environments characterized by elevated channel noise. To address these challenges, a noise-tolerant method is proposed to facilitate accurate carrier phase recovery (CPR) with reduced complexity. This method merges a second-order feedback loop and a feedforward stage to achieve accurate estimation. The simulation results indicate that the proposed method surpasses traditional methods in terms of noise tolerance and resource efficiency. Particularly, the BER of the proposed method can be decreased to 6.7×103 at a signal-to-noise ratio (SNR) of 4.5 dB, in contrast to a BER of 0.25 for the traditional method. Additionally, the resource consumption of the proposed method can be decreased by 64% under equivalent conditions. Furthermore, the experimental results reveal that the phase estimation error and BER for the proposed method are 2.1×104 and 7.5×104, respectively, when the received power is −41 dBm. These values are significantly lower than those achieved with traditional methods, which obtain errors of 1.85×103 and a BER of 0.48, respectively. Full article
(This article belongs to the Special Issue Satellite Communication Technologies and Challenges)
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10 pages, 8429 KiB  
Article
Study on Fatigue Fracture Behavior of S32750 Duplex Stainless Steel at Different Solution Temperatures
by Shun Bao, Han Feng, Zhigang Song, Jianguo He, Xiaohan Wu and Yang Gu
Crystals 2025, 15(1), 44; https://doi.org/10.3390/cryst15010044 - 31 Dec 2024
Cited by 1 | Viewed by 696
Abstract
This paper investigates the tensile and low-cycle fatigue characteristics of S32750 duplex stainless steel subjected to two distinct solid solution treatment temperatures. The microstructures, fracture surfaces, and slip systems of the tested steel were analyzed using optical microscopy (OM), scanning electron microscopy (SEM), [...] Read more.
This paper investigates the tensile and low-cycle fatigue characteristics of S32750 duplex stainless steel subjected to two distinct solid solution treatment temperatures. The microstructures, fracture surfaces, and slip systems of the tested steel were analyzed using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The findings reveal that elevating the solid solution treatment temperature from 1080 °C to 1180 °C results in an increase in the yield strength of the tested steel by approximately 36 MPa and a substantial enhancement in fatigue life by 34%. Microhardness measurements indicate that the degree of hardening in austenite post-fatigue failure significantly surpasses that of ferrite. The variation in solid solution temperature alters the ferrite and austenite content within the matrix, consequently affecting the strain distribution between the two phases. The high-temperature solid solution treatment effectively enhances the two-phase strain-bearing capacity of the tested steel. Following the 1180 °C solid solution treatment, no cloud-like dislocation patterns were observed in the ferrite; instead, they were replaced by a proliferation of thick, interwoven dislocation bundles. In contrast, the dislocations within the austenite predominantly consist of ordered planar slip and twinning. The primary contributor to the extended fatigue life is the increased number of absorbed dislocations within the ferrite grains. Full article
(This article belongs to the Special Issue Advanced High-Strength Steel)
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19 pages, 10251 KiB  
Article
Nanosized κ-Carbide and B2 Boosting Strength Without Sacrificing Ductility in a Low-Density Fe-32Mn-11Al Steel
by Changwei He, Yongfeng Shen, Wenying Xue, Zhijian Fan and Yiran Zhou
Nanomaterials 2025, 15(1), 48; https://doi.org/10.3390/nano15010048 - 30 Dec 2024
Cited by 2 | Viewed by 861
Abstract
High-performance lightweight materials are urgently needed because of energy savings and emission reduction. Here, we design a new steel with a low density of 6.41 g/cm3, which is a 20% weight reduction compared to the conventional steel. The mechanical properties and [...] Read more.
High-performance lightweight materials are urgently needed because of energy savings and emission reduction. Here, we design a new steel with a low density of 6.41 g/cm3, which is a 20% weight reduction compared to the conventional steel. The mechanical properties and microstructures of the steels prepared with different routes are systematically explored by utilizing uniaxial tensile testing and transmission electron microscopy. The steel processed by cold rolling and recrystallization annealing at 950 °C for 15 min shows an ultra-high yield strength of 1241 ± 10 MPa, while retaining a good ductility of 38 ± 1%. The high yield strength is mainly related to the synergistic precipitation strengthening introduced by nanoscale B2 and κ′-carbides. It is encouraging to notice that the yield strength increased without scarifying ductility, compared to the ST steel. The key reason is that the high strain hardening rate is activated by combined factors, including the blockage of numerous twins and nanoscale B2 to the dislocation movements, and dynamic slip band refinement. This study is instructive for concurrently enhancing the strength and ductility of austenitic lightweight steels with fully recrystallized grains and dual nano-precipitates. Full article
(This article belongs to the Section 2D and Carbon Nanomaterials)
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18 pages, 7248 KiB  
Article
Research on the Optimal Control of Working Oil Pressure of DCT Clutch Based on Linear Quadratics Form
by Guifa Shi, Houzhong Zhang, Xiangtian Yang, Xing Xu and Xiaoqiang Sun
Machines 2024, 12(12), 903; https://doi.org/10.3390/machines12120903 - 10 Dec 2024
Cited by 1 | Viewed by 752
Abstract
The control of the vehicle transmission system is of great significance to driving comfort. In order to design a controller for smooth shifting and comfortable driving, a dynamic model of dual-clutch transmission is established in this paper. An optimal control strategy for clutch [...] Read more.
The control of the vehicle transmission system is of great significance to driving comfort. In order to design a controller for smooth shifting and comfortable driving, a dynamic model of dual-clutch transmission is established in this paper. An optimal control strategy for clutch oil pressure based on linear quadratics is proposed, which is used to optimally control the oil pressure of two clutches in the torque stage and inertia stage. The control strategy selects the slipping work and jerk as evaluation indices of shift quality and establishes an optimization objective function. On the premise of optimizing the input torque, the relative speed difference between the engine and the sliding clutch in the inertia stage is adjusted. Through the optimal trajectory control of the wet clutch oil pressure, slipping work and jerk are reduced, thereby improving driving comfort. The simulation results show that the slipping work and jerk generated by the system during the shift stage are reduced, and the shift quality is improved. Additionally, compared with the controller using the MATLAB particle swarm optimization algorithm, the response speed of the proposed controller is faster, the slipping work and jerk are better reduced, and the shift quality is improved. Full article
(This article belongs to the Section Automation and Control Systems)
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