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Keywords = constant stress-rate test

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22 pages, 2219 KiB  
Article
Numerical Modeling of Expansive Soil Behavior Using an Effective Stress-Based Constitutive Relationship for Unsaturated Soils
by Sahand Seyfi, Ali Ghassemi and Rashid Bashir
Geotechnics 2025, 5(3), 53; https://doi.org/10.3390/geotechnics5030053 - 5 Aug 2025
Abstract
Previous studies have extensively applied the generalized consolidation theory, which incorporates a two-stress state variable framework, to predict the volumetric behavior of unsaturated expansive soils under varying mechanical stress and matric suction. A key requirement for this approach is a constitutive surface that [...] Read more.
Previous studies have extensively applied the generalized consolidation theory, which incorporates a two-stress state variable framework, to predict the volumetric behavior of unsaturated expansive soils under varying mechanical stress and matric suction. A key requirement for this approach is a constitutive surface that links the soil void ratio to both net stress and matric suction. A large number of fitting parameters are typically needed to accurately fit a two-variable void ratio surface equation to laboratory test data. In this study, a single-stress state variable framework was adopted to describe the void ratio as a function of effective stress for unsaturated soils. The proposed approach was applied to fit void ratio–effective stress constitutive curves to laboratory test data for two different expansive clays. Additionally, a finite element model coupling variably saturated flow and stress–strain analysis was developed to simulate the volume change behavior of expansive clay subjected to moisture fluctuations. The model utilizes suction stress to compute the effective stress field and incorporates the dependency of soil modulus on volumetric water content based on the proposed void ratio–effective stress relationship. The developed numerical model was validated against a benchmark problem in which a layer of Regina expansive clay was subjected to a constant infiltration rate. The results demonstrate the effectiveness of the proposed model in simulating expansive soil deformations under varying moisture conditions over time. Full article
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24 pages, 2179 KiB  
Article
Time-Dependent Rheological Behavior and MPS Simulation of Cement–Bentonite Slurries with Hydration Accelerators for Borehole Backfilling Applications
by Shinya Inazumi, Kazuhiko Tazuke and Seiya Kashima
J. Compos. Sci. 2025, 9(7), 361; https://doi.org/10.3390/jcs9070361 - 10 Jul 2025
Viewed by 578
Abstract
This study investigates cement–bentonite slurries with hydration accelerators for borehole backfilling applications in infrastructure reconstruction projects. Two formulations with different accelerator dosages (5 and 10 kg/m3) were evaluated through combined experimental testing and Moving Particle Semi-implicit (MPS) numerical modeling to optimize [...] Read more.
This study investigates cement–bentonite slurries with hydration accelerators for borehole backfilling applications in infrastructure reconstruction projects. Two formulations with different accelerator dosages (5 and 10 kg/m3) were evaluated through combined experimental testing and Moving Particle Semi-implicit (MPS) numerical modeling to optimize material performance. The research focuses on time-dependent rheological evolution and its impact on construction performance, particularly bleeding resistance and workability retention. Experimental flow tests revealed that both formulations maintained similar initial flowability (240–245 mm spread diameter), but the higher accelerator dosage resulted in 33% flow reduction after 60 min compared to 12% for the lower dosage. Bleeding tests demonstrated significant improvement in phase stability, with bleeding rates reduced from 2.5% to 1.5% when accelerator content was doubled. The MPS framework successfully reproduced experimental behavior with prediction accuracies within 3%, enabling quantitative analysis of time-dependent rheological parameters through inverse analysis. The study revealed that yield stress evolution governs both flow characteristics and bleeding resistance, with increases several hundred percent over 60 min while plastic viscosity remained relatively constant. Critically, simulations incorporating time-dependent viscosity changes accurately predicted bleeding behavior, while constant-viscosity models overestimated bleeding rates by 60–130%. The higher accelerator formulation (10 kg/m3) provided an optimal balance between initial workability and long-term stability for typical borehole backfilling operations. This integrated experimental–numerical approach provides practical insights for material optimization in infrastructure reconstruction projects, particularly relevant for aging infrastructure requiring proper foundation treatment. The methodology offers construction practitioners a robust framework for material selection and performance prediction in borehole backfilling applications, contributing to improved construction quality and reduced project risks. Full article
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18 pages, 2421 KiB  
Review
Frictional Experiments on Granitic Faults: New Insights into Continental Earthquakes and Micromechanical Mechanisms
by Huiru Lei, Shimin Liu and Wenhao Dai
Appl. Sci. 2025, 15(13), 7207; https://doi.org/10.3390/app15137207 - 26 Jun 2025
Viewed by 312
Abstract
Granitic faults within the crystalline upper-to-middle continental crust play a critical role in accommodating tectonic deformation and controlling earthquake nucleation. To better understand their frictional behavior, we review experimental studies conducted under both dry and hydrothermal conditions using velocity-stepping (VS), constant-velocity (CV), and [...] Read more.
Granitic faults within the crystalline upper-to-middle continental crust play a critical role in accommodating tectonic deformation and controlling earthquake nucleation. To better understand their frictional behavior, we review experimental studies conducted under both dry and hydrothermal conditions using velocity-stepping (VS), constant-velocity (CV), and slide-hold-slide (SHS) tests. These approaches allow the quantification of frictional strength, velocity dependence, and healing behavior across a range of conditions. Our synthesis highlights that the friction coefficient of granite gouges decreases with increasing temperature and pore fluid pressure, decreasing slip velocity, and increasing slip displacement. The velocity-weakening regime shifts to higher temperatures with increasing slip velocity or decreasing pore fluid pressure. Temperature, normal stress, pore fluid pressure, and slip velocity interact to modulate frictional stability. In particular, microstructural observations reveal that grain size reduction, pressure solution creep, and fluid-assisted chemical processes are key mechanisms governing transitions between velocity-weakening and velocity-strengthening regimes. These insights support the growing application of microphysical-based models, which integrate micromechanical processes and offer improved extrapolation from the laboratory to natural fault systems compared to classical rate-and-state friction laws. The collective evidence underscores the importance of considering fault rheology in a temperature- and fluid-sensitive context, with implications for interpreting seismic cycle behavior in continental regions. Full article
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18 pages, 4203 KiB  
Article
Long-Term Anisotropic Mechanical Characterization of Layered Shale—An Experimental Study for the BaoKang Tunnel of the Zhengwan Railway, China
by Jun Zhao, Changming Li and Wei Huang
Processes 2025, 13(6), 1900; https://doi.org/10.3390/pr13061900 - 16 Jun 2025
Viewed by 430
Abstract
With the further implementation and development of the Western Development Strategy, studying the mechanical behavior and deformation characteristics of deep-buried tunnels in layered hard rock under high ground stress conditions holds considerable engineering significance. To study the mechanical properties and long-term deformation and [...] Read more.
With the further implementation and development of the Western Development Strategy, studying the mechanical behavior and deformation characteristics of deep-buried tunnels in layered hard rock under high ground stress conditions holds considerable engineering significance. To study the mechanical properties and long-term deformation and failure characteristics of different bedding stratified rocks, this research employed an MTS815 electro-hydraulic servo rock testing system and a French TOP rheometer. Triaxial compression tests, rheological property tests, and long-term cyclic and unloading tests were conducted on shale samples under varying confining pressures and bedding angles. The results indicate that (1) under triaxial compression, shale demonstrates pronounced anisotropic behavior. When the confining pressure is constant, the peak strength of the rock sample exhibits a “U”-shaped variation with the bedding angle (its minimum value at 60°). For a fixed bedding angle, the peak strength of the rock sample progressively increases as the confining pressure rises. (2) The mode of shale failure varies with the angle: at 0°, shale exhibits conjugate shear failure; at 30°, shear slip failure along the bedding is controlled by the bedding weak plane; at 60° and 90°, failure occurs through the bedding. (3) During the creep process of layered shale, brittle failure characteristics are evident, with microcracks within the sample gradually failing at stress concentration points. The decelerated and stable creep stages are prominent; while the accelerated creep stage is less noticeable, the creep rate increases with increasing stress level. (4) Under low confining pressure, the peak strength during cyclic loading and unloading creep processes is lower than that of conventional triaxial tests when the bedding plane dip angles are 0° and 30°, which is the opposite at 60° and 90°. (5) In the cyclic loading and unloading process, Poisson’s ratio gradually increases, whereas the elastic modulus, shear modulus, and bulk modulus gradually decrease. Full article
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18 pages, 7815 KiB  
Article
Short-Beam Shear Fatigue Behavior on Unidirectional GLARE: Mean Shear Stress Effect, Scatter, and Anisotropy
by Douglas G. Caetano, Hector G. Kotik, Juan E. Perez Ipiña and Enrique M. Castrodeza
Fibers 2025, 13(6), 77; https://doi.org/10.3390/fib13060077 - 9 Jun 2025
Viewed by 989
Abstract
This paper investigates the effect of mean shear stress on short-beam shear fatigue in a GLARE 1-3/2 commercial fiber–metal laminate (FML). This study explores three shear stress ratios (Rτ 0.1, 0.3, and 0.5) and two material orientations (longitudinal and transversal) under [...] Read more.
This paper investigates the effect of mean shear stress on short-beam shear fatigue in a GLARE 1-3/2 commercial fiber–metal laminate (FML). This study explores three shear stress ratios (Rτ 0.1, 0.3, and 0.5) and two material orientations (longitudinal and transversal) under constant amplitude fatigue. Different stress levels for each Rτ value were explored to obtain failures between 103 and 106 load cycles. The experimental results reveal anisotropy, with transversal specimens exhibiting lower performance and increased scatter. The mean shear stress effect is discussed herein, with insights into the critical role of mean shear of fatigue performance. Rτ 0.1 was the most severe condition and Rτ 0.5 was the least severe. The Rτ 0.3 condition produced steeper S-N curves, indicating that the combined effect of mean shear stress and shear stress amplitude led to a higher rate of damage accumulation. The fractographic analysis investigated the failure modes and confirmed the damage dominated by Mode II, supporting the test methodology employed. Full article
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10 pages, 1472 KiB  
Technical Note
Modeling of Tensile Tests Flow Curves Using an Explicit Piecewise Inverse Approach
by Aditya Vuppala, Holger Brüggemann, David Bailly and Emad Scharifi
Metals 2025, 15(6), 638; https://doi.org/10.3390/met15060638 - 5 Jun 2025
Viewed by 438
Abstract
Tensile tests are a common method for characterizing plastic behavior for sheet metal forming applications. During tensile testing at the beginning of the deformation, the stress state is uniaxial; however, as the deformation proceeds, the state changes to triaxial, making the post-processing of [...] Read more.
Tensile tests are a common method for characterizing plastic behavior for sheet metal forming applications. During tensile testing at the beginning of the deformation, the stress state is uniaxial; however, as the deformation proceeds, the state changes to triaxial, making the post-processing of experimental data challenging using analytical methods. In contrast, inverse approaches in which the behavior is represented by constitutive equations and the parameters are fitted using an iterative procedure are extremely dependent on the empirical equation chosen at the outset and can be computationally expensive. The inverse piecewise flow curve determination method, previously developed for compression tests, is extended in this paper to tensile testing. A stepwise approach is proposed to calculate constant strain rate flow curves accounting for the unique characteristics of tensile deformation. To capture the effects of localized strain rate variations during necking, a parallel flow curve determination strategy is introduced. Tensile test flow curves for manganese-boron steel 22MnB5, a material commonly used in hot stamping applications, are determined, and the approach is demonstrated for virtual force–displacement curves. It has been shown that these curves can replicate the virtual experimental flow curves data with a maximum deviation of 1%. Full article
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13 pages, 2686 KiB  
Article
Strain Rate Effect on Artificially Cemented Clay with Fully Developed and Developing Structure
by Qiang Li, Beatrice Anne Baudet and Xiaoyan Zhang
Appl. Sci. 2025, 15(11), 5839; https://doi.org/10.3390/app15115839 - 22 May 2025
Viewed by 388
Abstract
The rapid expansion of land reclamation necessitates a fundamental understanding of the strain rate effects on structured clays. While the rate effect has been widely studied in various soils, the interplay between bond structure and strain rate sensitivity remains unclear. This study investigates [...] Read more.
The rapid expansion of land reclamation necessitates a fundamental understanding of the strain rate effects on structured clays. While the rate effect has been widely studied in various soils, the interplay between bond structure and strain rate sensitivity remains unclear. This study investigates these mechanisms using artificially cemented kaolin (ACK) with controlled curing periods (2 and 30 days) to simulate naturally bonded clays. A series of undrained triaxial tests was conducted under low (100 kPa) and high (600 kPa) confining stresses, employing constant strain rates (0.01–5%/h) pre-peak and stepwise rate changes post-peak. The results reveal that the strain rate effects are governed by the bond structure maturity and drainage mechanisms. For the 30-day curing ACK, the pre-peak strength under low confining stress shows minimal rate sensitivity due to the rigid bond, while high confining stress induces a “negative” rate effect attributed to localised drainage along shear planes. The post-peak behaviour consistently exhibits a positive isotach-type rate effect (+3%/log-cycle) driven by viscous sliding. In contrast, the 2-day curing ACK displays negative rate effects pre-peak influenced by ongoing curing and post-peak strength reductions (−8%/log-cycle) linked to stick-slip dynamics. These findings establish a framework for predicting rate-dependent behaviour in structured clays, offering insights into land reclamation and subsequent construction work. Full article
(This article belongs to the Section Civil Engineering)
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26 pages, 12252 KiB  
Article
Phase-Field Simulation of the Creep Mechanism in the AZ31 Magnesium Alloy Under Discontinuous Dynamic Recrystallization Dominance
by Alireza Rezvani, Ramin Ebrahimi and Ebad Bagherpour
Crystals 2025, 15(5), 453; https://doi.org/10.3390/cryst15050453 - 12 May 2025
Viewed by 619
Abstract
Discontinuous dynamic recrystallization is a critical microstructural evolution mechanism during high-temperature deformation, influencing material properties significantly. This study develops a two-dimensional phase-field model to predict steady-state creep rates in the AZ31 magnesium alloy, focusing on DRX during creep. To enhance simulation accuracy, initial [...] Read more.
Discontinuous dynamic recrystallization is a critical microstructural evolution mechanism during high-temperature deformation, influencing material properties significantly. This study develops a two-dimensional phase-field model to predict steady-state creep rates in the AZ31 magnesium alloy, focusing on DRX during creep. To enhance simulation accuracy, initial microstructures are generated from optical microscopy data, enabling simulations at larger scales with higher representativeness. A novel nucleation methodology is implemented, eliminating the need for nuclei order parameter adaptation, improving computational efficiency. Finite element analysis (FEA) is integrated to capture initial instantaneous deformation. The Kocks–Mecking model is employed to describe the evolution of average dislocation density, accounting for work hardening and dynamic recovery within the initial polycrystalline microstructure. Instead of conventional creep testing, impression creep, a cost-effective alternative, is used for validation. This method provides constant stress and steady penetration velocity, simulating creep conditions effectively. The model accurately predicts recrystallization kinetics and microstructural evolution, exhibiting a strong correlation with experimental results, with an error of approximately 5%. This research provides a robust and efficient approach for predicting creep behavior in high-temperature applications, vital for optimizing material selection and predicting component lifespan in industries. The methodology offers a significant advancement in understanding and predicting DRX-driven creep behavior. Full article
(This article belongs to the Special Issue Advances in Processing, Simulation and Characterization of Alloys)
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15 pages, 6642 KiB  
Article
Analysis of Shear Crushing Behavior of Graded Calcareous Sand in Building Applications
by Shuyue Liu, Peng Cao and Ziyu Wang
Buildings 2025, 15(9), 1443; https://doi.org/10.3390/buildings15091443 - 24 Apr 2025
Viewed by 327
Abstract
Calcareous sand, a critical construction material in reef engineering and building foundations, possesses unique internal microstructures and inherent mechanical properties. Given these characteristics, it is essential to thoroughly evaluate its strength under various loading conditions to ensure its reliability in building applications. This [...] Read more.
Calcareous sand, a critical construction material in reef engineering and building foundations, possesses unique internal microstructures and inherent mechanical properties. Given these characteristics, it is essential to thoroughly evaluate its strength under various loading conditions to ensure its reliability in building applications. This study examines the strength, deformation, and failure characteristics of calcareous sand through consolidated drained shear failure tests using a GDS stress path triaxial apparatus. The effects of shear rate, particle gradation, and compactness are systematically investigated to assess their impact on structural stability in building foundations and load-bearing applications. The results indicate that at low confining pressures, calcareous sand exhibits strain softening, whereas at higher confining pressures, strain hardening is observed. For samples with the same gradation, both peak deviatoric stress and failure strain increase linearly with confining pressure. The volume strain evolution during shear follows three stages: shear shrinkage, shear dilatancy, and stabilization. At low confining pressures, dilatancy is favored, while high confining pressures promote shrinkage. Additionally, under constant confining pressure, peak strength increases and failure strain decreases linearly with compactness. Increasing the loading rate from 0.01 to 0.1 mm/min results in a slight increase in the friction angle, with minimal impact on cohesion. Particle gradation plays a significant role in determining the shear strength of calcareous sand, as its effects vary depending on the combination of compactness and gradation. These findings provide valuable insights for the design and construction of stable building foundations, roadbeds, and other load-bearing structures in reef engineering and coastal developments, where calcareous sand is widely used. Full article
(This article belongs to the Section Building Materials, and Repair & Renovation)
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18 pages, 10080 KiB  
Article
SCC Susceptibility of Polystyrene/TiO2 Nanocomposite-Coated Thin-Sheet Aluminum Alloy 2024—T3 in 3.5% NaCl
by Cheng-fu Chen, Brian Baart, John Halford and Junqing Zhang
Eng 2025, 6(4), 83; https://doi.org/10.3390/eng6040083 - 21 Apr 2025
Viewed by 507
Abstract
The effectiveness of polystyrene (PS)/TiO2 nanocomposite coatings in reducing stress–corrosion cracking (SCC) susceptibility of aluminum alloy 2024-T3 (AA2024-T3) was evaluated using an accelerated stress–corrosion test. Polystyrene (PS)-based coatings incorporating TiO2 nanoparticles with three different aspect ratios (ARs) were compared to a [...] Read more.
The effectiveness of polystyrene (PS)/TiO2 nanocomposite coatings in reducing stress–corrosion cracking (SCC) susceptibility of aluminum alloy 2024-T3 (AA2024-T3) was evaluated using an accelerated stress–corrosion test. Polystyrene (PS)-based coatings incorporating TiO2 nanoparticles with three different aspect ratios (ARs) were compared to a bare polystyrene coating. A compact tension (CT) specimen (5 mm thick) was coated for testing in a synergistic stress–corrosion environment. A slow constant displacement rate of 1.25 nm/s was applied in the load-line direction of the specimen to gradually open the crack mouth, while the crack tip was periodically dosed with a 3.5 wt.% NaCl solution. Load-displacement data were recorded and analyzed to calculate the J-integral, according to Standard ASTM E1820, for each coated specimen tested under laboratory-controlled SCC conditions. The fracture toughness, stress intensity, and six other SCC susceptibility indices were further developed to compare the performance of each coating in enhancing SCC resistance. The results revealed a strong dependence of SCC resistance on the nanoparticle aspect ratio, with the nanocomposite coating featuring an AR of 1 performing the best. The SCC behavior was reflected in the fractography of the fractured halves of a specimen, where cleavage was observed during the very slow, stable cracking stage, and dimples formed as a result of fast, unstable cracking toward the end of testing. These findings highlight the potential of tailored nanocomposite coatings to enhance the durability of aerospace-grade aluminum alloys. Full article
(This article belongs to the Section Materials Engineering)
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20 pages, 6149 KiB  
Article
In Situ and Laboratory Testing of Boom Clay at Shallow Depths in Belgium
by Maria Konstadinou, Etienne A. Alderlieste, Cor Zwanenburg, Cihan Cengiz, Anderson Peccin da Silva and Charlotte J. W. van Verseveld
Geotechnics 2025, 5(2), 23; https://doi.org/10.3390/geotechnics5020023 - 28 Mar 2025
Viewed by 1026
Abstract
The shear strength and compression properties of stiff Boom clay from Belgium at a depth of about 16.5 to 28 m were investigated by means of cone penetration and laboratory testing. The latter consisted of index classification, constant rate of strain, triaxial, direct [...] Read more.
The shear strength and compression properties of stiff Boom clay from Belgium at a depth of about 16.5 to 28 m were investigated by means of cone penetration and laboratory testing. The latter consisted of index classification, constant rate of strain, triaxial, direct simple shear and unconfined compression tests. The Boom clay samples exhibited strong swelling tendencies. The suction pressure was measured via different procedures and was compared to the expected in situ stress. The undrained shear strength profile determined from cone penetration tests (CPTs) was not compatible with the triaxial and direct simple shear measurements, which gave significantly lower undrained shear strength values. Micro-computed tomography (μCT) scans of the samples showed the presence of pre-existing discontinuities which may cause inconsistencies in the comparison of the laboratory test results with in situ data. The experimental data gathered in this study provide useful information for analyzing the mechanical behaviour of Boom clay at shallow depths considering that most investigations in the literature have been carried out on deep Boom clay deposits. Full article
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18 pages, 3072 KiB  
Article
Building a Novel Electromechanical-Thermal Model for Semi-Solid-State Batteries
by W. W. Wang, S. T. Zhi, X. T. Xu, X. Y. Liu and H. S. Zhen
Energies 2025, 18(4), 844; https://doi.org/10.3390/en18040844 - 11 Feb 2025
Viewed by 875
Abstract
This article develops an electromechanical-thermal model for semi-solid-state batteries using Software COMSOL Multi-physics. The battery’s three-dimensional structure is firstly simplified into a one-dimensional electrochemical model (P2D), which combines the solid heat transfer module and the solid mechanics module. The total power consumption of [...] Read more.
This article develops an electromechanical-thermal model for semi-solid-state batteries using Software COMSOL Multi-physics. The battery’s three-dimensional structure is firstly simplified into a one-dimensional electrochemical model (P2D), which combines the solid heat transfer module and the solid mechanics module. The total power consumption of the battery, obtained from the P2D model, is used to calculate the battery temperature and the lithium concentration. Then, stress analysis of the anode active particles is conducted, and the battery temperature is fed back into both the electrochemical and mechanical models. To validate the model, constant current charge/discharge cycling experiments, as well as tests on the basic electrical parameters and temperature of the battery, are conducted. The electromechanical-thermal model developed in this study serves as an effective tool for simulating semi-solid-state lithium-ion batteries, which can predict the battery’s performance under various operating conditions. The simulation results from the numerical model are consistent with experimental data at low charge/discharge rates, while slightly larger discrepancies are observed at high charge/discharge rates, with the accuracy remaining over 90%. Further, the thermal expansion behavior of the batteries with silicon-carbon anodes during the charge-discharge process can be examined using the developed model. Full article
(This article belongs to the Section D2: Electrochem: Batteries, Fuel Cells, Capacitors)
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12 pages, 3553 KiB  
Article
Environmental Influences on Seed Germination and Seedling Emergence in Four Echinochloa Taxa
by Guohui Yuan, Yuan Gao, Jiapeng Fang, Guohui Shen and Zhihui Tian
Agronomy 2025, 15(2), 401; https://doi.org/10.3390/agronomy15020401 - 3 Feb 2025
Cited by 2 | Viewed by 1190
Abstract
Echinochloa species are troublesome weeds that cause serious problems in paddy fields. Due to the fact that the genus Echinochloa comprises numerous species and subspecies, research on its seed germination and emergence ecology is still insufficient. In this study, the influence of varying [...] Read more.
Echinochloa species are troublesome weeds that cause serious problems in paddy fields. Due to the fact that the genus Echinochloa comprises numerous species and subspecies, research on its seed germination and emergence ecology is still insufficient. In this study, the influence of varying temperatures; light, osmotic, and saline conditions; and depth of seed burial on the germination of Echinochloa seeds and the emergence of seedlings was determined through laboratory and pot tests: E. crus-galli var. crus-galli, E. crus-galli var. mitis, E. crus-galli var. praticola, and E. caudata. Seed germination of the constant temperatures in the four Echinochloa taxa was examined between 15 and 40 °C, and optimum germination occurred over the following temperature ranges: 25–35 °C for E. crus-galli var. crus-galli; 15–25 °C for E. crus-galli var. mitis; 15–40 °C for E. crus-galli var. praticola; and 15–35 °C for E. caudata. Fluctuating temperatures were conducive to seed germination in all four Echinochloa taxa. Except for E. crus-galli var. crus-galli and E. crus-galli var. mitis exposed to very acidic conditions (pH = 4), germination of seedlings from the four taxa of Echinochloa was not evidently affected by pH or light. Seed germination of the four Echinochloa taxa decreased as water stress decreased (<−0.2 MPa); however, it occurred across a wide spectrum of salt concentrations (0–320 mM NaCl). The seeds that were placed 0–0.5 cm below the surface had the highest rate of seedling emergence, which declined gradually as burial depth increased. This result demonstrates that deep tillage is an efficient management method for decreasing the seedling emergence of various weed species. This study’s findings will enhance our comprehension of the conditions necessary for the germination and emergence of Echinochloa seeds, as well as furnish information that may assist in managing its growth. Full article
(This article belongs to the Special Issue Ecology and Management of Weeds in Different Situations)
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13 pages, 3907 KiB  
Article
Experimental Study on the Anti-Scouring Characteristics of Bedrock in Engineering Reservoir Areas That Are Conducive to Sustainable Development
by Zhijing Li, Yisen Wang, Shiming Yao, Zhongwu Jin and Zhixinghua Hu
Sustainability 2025, 17(3), 977; https://doi.org/10.3390/su17030977 - 25 Jan 2025
Viewed by 1966
Abstract
High-speed water flow conditions can cause erosion of the bedrock in engineering areas. Due to the lack of accurate evaluation of bedrock scour and erosion rates, there has been a consumption of manpower and resources without achieving satisfactory engineering outcomes. Therefore, studying the [...] Read more.
High-speed water flow conditions can cause erosion of the bedrock in engineering areas. Due to the lack of accurate evaluation of bedrock scour and erosion rates, there has been a consumption of manpower and resources without achieving satisfactory engineering outcomes. Therefore, studying the scouring and erosion effects of water flow on bedrock is of significant importance for maintaining the sustainable development and safety of engineering projects. Using the bedrock prototype from the Xiaonanhai site in the upper reaches of the Yangtze River, a model test device was developed to conduct anti-scour tests on the bedrock. The study quantitatively examined the basic physical properties, incipient erosion velocity, and erosion rates of different types of bedrock. The study found that the prototype bedrock under natural exposure, submerged immersion, and alternating wet and dry conditions showed a trend of decreased tensile strength, with the alternating wet and dry conditions being the most detrimental to maintaining the physical properties of the rock mass. The anti-scour velocity of silty claystone and clayey siltstone samples increased with the increase in tensile strength, and the erosion rate increased with the increase in shear stress. If the shear stress is kept constant, the erosion rate decreases with the increase in tensile strength. The erosion rate is inversely proportional to the ratio of the bedrock’s tensile strength to the riverbed shear stress, with the fitting relationship showing a piecewise linear distribution. The research results can provide guidance for the safe production of engineering involving bedrock erosion in engineering reservoir areas that are conducive to sustainable development. Full article
(This article belongs to the Special Issue Sediment Movement, Sustainable Water Conservancy and Water Transport)
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8 pages, 1408 KiB  
Article
Combinatorial Deposition and Wear Testing of HiPIMS W-C Films
by Joern Kohlscheen and Christian Bareiss
Coatings 2025, 15(1), 115; https://doi.org/10.3390/coatings15010115 - 20 Jan 2025
Cited by 1 | Viewed by 1246
Abstract
We used high-power impulse magnetron sputtering (HiPIMS) to deposit tungsten carbide films for superior wear protection in abrasive environments. In order to sample different W-to-C ratios more efficiently, a combinatorial approach was chosen. A single sputter target with two equal segments was used, [...] Read more.
We used high-power impulse magnetron sputtering (HiPIMS) to deposit tungsten carbide films for superior wear protection in abrasive environments. In order to sample different W-to-C ratios more efficiently, a combinatorial approach was chosen. A single sputter target with two equal segments was used, consisting of an upper tungsten and lower graphite segment. This allowed us to vertically sample various elemental compositions in just one deposition run without creating graphitic nano-layers by rotating the substrate holder. The substrate bias voltage, being one of the most effective process parameters in physical vapor deposition (PVD), was applied in both constant and pulsed modes (the latter synchronized to the target pulse). A direct comparison of the different modes has not been performed so far for HiPIMS W-C (separated W and C targets). The resulting coating properties were mainly analyzed by nano-hardness testing and X-ray diffraction. In general, the W2C phase prevailed in tungsten-rich coatings with pulsed bias, leading to slightly higher tungsten contents. Hardness reached maximum values of up to 35 GPa in the center region between the two segments, where a mix of W2C and WC1-x phases occurs. With pulsed bias, voltage hardnesses are slightly higher, especially for tungsten-rich films. In those cases, compressive stress was also found to be higher when compared to constant bias. Erosive wear testing by blasting with alumina grit showed that the material removal rate followed basically the coating’s hardness but surprisingly reached minimum wear loss for W2C single-phase films just before maximum hardness. In contrast to previous findings, low friction that requires higher carbon contents of at least 50 at. % is not favorable for this type of wear. Full article
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