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Search Results (2,048)

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Keywords = fracture zone

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28 pages, 24112 KB  
Article
Statistical and Geomatic Approaches to Typological Characterization and Susceptibility Mapping of Mass Movements in Northwestern Morocco’s Alpine Zone
by Mohamed Mastere, Ayyoub Sbihi, Anas El Ouali, Sanae Bekkali, Oussama Arab, Danielle Nel Sanders, Benyounes Taj, Ibrahim Ouchen, Noamen Rebai and Ali Bounab
Geomatics 2025, 5(4), 51; https://doi.org/10.3390/geomatics5040051 - 3 Oct 2025
Abstract
The Rif Mountains in northern Morocco are highly exposed to geohazards, particularly earthquakes and mass movements. In this context, the Zoumi region is most affected, showing various mass movement types involving both unconsolidated and solid materials. This study evaluates the region’s susceptibility to [...] Read more.
The Rif Mountains in northern Morocco are highly exposed to geohazards, particularly earthquakes and mass movements. In this context, the Zoumi region is most affected, showing various mass movement types involving both unconsolidated and solid materials. This study evaluates the region’s susceptibility to mass movements using logistic regression (LR), applied for the first time in this area. The model incorporates eight key predisposing factors known to influence mass movement: slope gradient, slope aspect, land use, drainage density, elevation, lithology, fracturing density, and earthquake isodepths. Historical mass movements were mapped using remote sensing and field surveys, and statistical analysis calculation was conducted to analyze their spatial correlation with these environmental conditioning factors. A mass movement susceptibility (MMS) map was produced, classifying the region into four susceptibility levels, ranging from low to very high. Landslides were the most frequent movement type (36%). The LR model showed strong predictive performance, with an AUC of 88%, confirming its robustness. The final map reveals that 42% of the Zoumi area falls within the high to very high susceptibility zones. These results highlight the importance of using advanced modeling approaches to support risk mitigation and land use planning in environmentally sensitive mountain regions. Full article
25 pages, 2339 KB  
Article
Rock Mass Failure Classification Based on FAHP–Entropy Weight TOPSIS Method and Roadway Zoning Repair Design
by Biao Huang, Qinghu Wei, Zhongguang Sun, Kang Guo and Ming Ji
Processes 2025, 13(10), 3154; https://doi.org/10.3390/pr13103154 - 2 Oct 2025
Abstract
After the original support system in the auxiliary transportation roadway of the northern wing of the Zhaoxian Mine failed, the extent of damage and deformation varied significantly across different sections of the drift. A single support method could not meet the engineering requirements. [...] Read more.
After the original support system in the auxiliary transportation roadway of the northern wing of the Zhaoxian Mine failed, the extent of damage and deformation varied significantly across different sections of the drift. A single support method could not meet the engineering requirements. Therefore, this paper conducted research on the classification of roadway damage and zoning repair. The overall damage characteristics of the roadway are described by three indicators: roadway deformation, development of rock mass fractures, and water seepage conditions. These are further refined into nine secondary indicators. In summary, a rock mass damage combination weighting evaluation model based on the FAHP–entropy weight TOPSIS method is proposed. According to this model, the degree of damage to the roadway is divided into five grades. After analyzing the damage conditions and support requirements at each grade, corresponding zoning repair plans are formulated by adjusting the parameters of bolts, cables, channel steel beams, and grouting materials. At the same time, the reliability of partition repair is verified using FLAC3D 6.0 numerical simulation software. Field monitoring results demonstrated that this approach not only met the support requirements for the roadway but also improved the utilization rate of support materials. This provides valuable guidance for the design of support systems for roadways with similar heterogeneous damage. Full article
(This article belongs to the Section Process Control and Monitoring)
19 pages, 2373 KB  
Article
Numerical Investigation of Fracture Behavior and Current-Carrying Capability Degradation in Bi2212/Ag Composite Superconducting Wires Subjected to Mechanical Loads Using Phase Field Method
by Feng Xue and Kexin Zhou
Modelling 2025, 6(4), 119; https://doi.org/10.3390/modelling6040119 - 1 Oct 2025
Abstract
Bi2Sr2CaCu2O8+x (Bi2212) high-temperature superconductor exhibits broad application prospects in strong magnetic fields, superconducting magnets, and power transmission due to its exceptional electrical properties. However, during practical applications, Bi2212 superconducting round wires are prone to mechanical [...] Read more.
Bi2Sr2CaCu2O8+x (Bi2212) high-temperature superconductor exhibits broad application prospects in strong magnetic fields, superconducting magnets, and power transmission due to its exceptional electrical properties. However, during practical applications, Bi2212 superconducting round wires are prone to mechanical loading effects, leading to crack propagation and degradation of superconducting performance, which severely compromises their reliability and service life. To elucidate the damage mechanisms under mechanical loading and their impact on critical current, this study establishes a two-dimensional model with existing cracks based on phase field fracture theory, simulating crack propagation behaviors under varying conditions. The results demonstrate that crack nucleation and propagation paths are predominantly governed by stress concentration zones. The transition zone width of cracks is controlled by the phase field length scale parameter. By incorporating electric fields into the phase field model, coupled mechanical-electrical simulations reveal that post-crack penetration causes significant current shunting, resulting in a marked decline in current density. The research quantitatively explains the mechanism of critical current degradation in Bi2212 round wires under tensile strain from a mechanical perspective. Full article
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40 pages, 8027 KB  
Article
Parametric Visualization, Climate Adaptability Evaluation, and Optimization of Strategies for the Subtropical Hakka Enclosed House: The Guangludi Case in Meizhou
by Yijiao Zhou, Zhe Zhou, Pei Cai and Nangkula Utaberta
Buildings 2025, 15(19), 3530; https://doi.org/10.3390/buildings15193530 - 1 Oct 2025
Abstract
Hakka traditional vernacular dwellings embody regionally specific climatic adaptation strategies. This study takes the Meizhou Guangludi enclosed house as a case study to evaluate its climate adaptability with longevity and passive survivability factors of the Hakka three-hall enclosed house under subtropical climatic conditions. [...] Read more.
Hakka traditional vernacular dwellings embody regionally specific climatic adaptation strategies. This study takes the Meizhou Guangludi enclosed house as a case study to evaluate its climate adaptability with longevity and passive survivability factors of the Hakka three-hall enclosed house under subtropical climatic conditions. A mixed research method is employed, integrating visualized parametric modeling analysis and on-site measurement comparisons to quantify wind, temperature, solar radiation/illuminance, and humidity, along with human comfort zone limits and building environment. The results reveal that nature erosion in the Guangludi enclosed house is the most pronounced during winter and spring, particularly on exterior walls below 2.8 m. Key issues include bulging, spalling, molding, and fractured purlins caused by wind-driven rain, exacerbated by low wind speeds and limited solar exposure, especially at test spots like the E8–E10 and N1–N16 southeast and southern walls below 1.5 m. Fungal growth and plant intrusion are severe where surrounding trees and fengshui forests restrict wind flow and lighting. In terms of passive survivability, the Guangludi enclosed house has strong thermal insulation and buffering, aided by the Huatai mound; however, humidity and day illuminance deficiencies persist in the interstitial spaces between lateral rooms and the central hall. To address these issues, this study proposes strategies such as adding ventilation shafts and flexible partitions, optimizing patio dimensions and window-to-wall ratios, retaining the spatial layout and Fengshui pond to enhance wind airflow, and reinforcing the identified easily eroded spots with waterproofing, antimicrobial coatings, and extended eaves. Through parametric simulation and empirical validation, this study presents a climate-responsive retrofit framework that supports the sustainability and conservation of the subtropical Hakka enclosed house. Full article
(This article belongs to the Section Architectural Design, Urban Science, and Real Estate)
21 pages, 6851 KB  
Article
Target Area Selection for Residual Coalbed Methane Drainage in Abandoned Multi-Seam Mines
by Gen Li, Yaxin Xiu, Qinjie Liu, Bin Zhang, Minke Duan, Youxing Yang and Chenye Guo
Appl. Sci. 2025, 15(19), 10619; https://doi.org/10.3390/app151910619 - 30 Sep 2025
Abstract
To optimize the location optimization of the coalbed methane (CBM) extraction target area in abandoned mines, based on the background of the Songzao mining area in Chongqing, theoretical analysis and numerical simulation research methods were comprehensively used to systematically evaluate the potential of [...] Read more.
To optimize the location optimization of the coalbed methane (CBM) extraction target area in abandoned mines, based on the background of the Songzao mining area in Chongqing, theoretical analysis and numerical simulation research methods were comprehensively used to systematically evaluate the potential of residual CBM resources in the goaf of the Songzao mining area. The stress-fracture evolution law and permeability enhancement characteristics of overlying strata under repeated mining of inclined multi-coal seams were deeply revealed, and the location optimization of the residual CBM extraction borehole target area was carried out. The results show that the amount of CBM resources in Songzao Coal Mine is 5.248 × 107 m3, accounting for 26.57% of the total resources, which is suitable for the extraction of CBM left in goaf. The maximum height of the overburden fracture zone caused by repeated mining of K2b, K1, and K3b coal seams in Songzao Coal Mine is 72.3 m, which is basically consistent with the results of the numerical simulation (69.76 m). The fracture development of overlying strata is in the distribution form of a symmetrical trapezoid and inclined asymmetrical trapezoid, and its development height increases with an increase in coal seam mining times, and finally forms a three-dimensional ‘O’-ring fracture area, which provides a channel and enrichment area for the effective migration of CBM. The significant permeability-increasing zone of overburden rock is stable in the range of 10~40 m above the roof of the K3b coal seam and is nearly trapezoidal. According to the calculation of the height prediction model of the fracture zone in the abandoned goaf, the fracture height of the long-term compaction of the Songzao Coal Mine is reduced to 63.74 m. Based on the stress-fracture evolution characteristics of the overburden rock, combined with the permeability-increasing characteristics of the overburden rock and the migration law of the remaining CBM, it is determined that the preferred position of the remaining CBM extraction target area of the Songzao Coal Mine should be in the upper corner of the fracture development area within the range of 10~32.47 m above the K36 coal seam. Full article
17 pages, 11223 KB  
Article
Hydrocarbon-Bearing Hydrothermal Fluid Migration Adjacent to the Top of the Overpressure Zone in the Qiongdongnan Basin, South China Sea
by Dongfeng Zhang, Ren Wang, Hongping Liu, Heting Huang, Xiangsheng Huang and Lei Zheng
Appl. Sci. 2025, 15(19), 10587; https://doi.org/10.3390/app151910587 - 30 Sep 2025
Abstract
The Qiongdongnan Basin constitutes a sedimentary basin characterized by elevated temperatures, significant overpressures, and abundant hydrocarbons. Investigations within this basin have identified hydrothermal fluid movements linked to overpressure conditions, comprising two vertically separated overpressured intervals. The shallow overpressure compartment is principally caused by [...] Read more.
The Qiongdongnan Basin constitutes a sedimentary basin characterized by elevated temperatures, significant overpressures, and abundant hydrocarbons. Investigations within this basin have identified hydrothermal fluid movements linked to overpressure conditions, comprising two vertically separated overpressured intervals. The shallow overpressure compartment is principally caused by a combination of undercompaction and clay diagenesis. In contrast, the deeper high-pressure compartment results from hydrocarbon gas generation. Numerical pressure modeling indicates late-stage (post-5 Ma) development of significant overpressure within the deep compartment. It is proposed that accelerated subsidence in the Pliocene-Quaternary initiated substantial gas generation, thereby promoting the formation of the deep overpressured system. Multiple organic maturation parameters, combined with fluid inclusion microthermometry, reveal a thermal anomaly adjacent to the upper boundary of the deep overpressured zone. This anomaly indicates vertical transport of hydrothermal fluids ascending from the underlying high-pressure zone. Laser Raman spectroscopy confirms the presence of both hydrocarbons and carbon dioxide within these migrating fluids. Integration of fluid inclusion thermometry with burial history modeling constrains the timing of hydrocarbon-carrying fluid charge to the interval from 4.2 Ma onward, synchronous with modeled peak gas generation and a phase of pronounced overpressure buildup. We propose that upon exceeding the fracture gradient threshold, fluid pressure triggered upward migration of deeply sourced, hydrocarbon-enriched fluids through hydrofracturing pathways. This process led to localized dissolution and fracturing near the top of the deep overpressured system, while simultaneously facilitating significant hydrocarbon accumulation and forming preferential accumulation zones. These findings provide critical insights into petroleum exploration in overpressured sedimentary basins. Full article
(This article belongs to the Special Issue Advances in Petroleum Exploration and Application)
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16 pages, 913 KB  
Article
Mechanisms of Energy Transfer and Failure Zoning in Rock Mass Blasting: A Mohr–Coulomb Theory and Numerical Simulation Study
by Wei Zhang, Renshan Chen, Kaibo Yang and Jin Li
Appl. Sci. 2025, 15(19), 10600; https://doi.org/10.3390/app151910600 - 30 Sep 2025
Abstract
This paper explores the mechanisms of energy transfer and failure zones in rock mass blasting. By combining theoretical derivation with numerical simulation, we examine the deformation, failure features, and source parameters of rock subjected to spherical charge blasting. Using the Mohr–Coulomb yield criterion, [...] Read more.
This paper explores the mechanisms of energy transfer and failure zones in rock mass blasting. By combining theoretical derivation with numerical simulation, we examine the deformation, failure features, and source parameters of rock subjected to spherical charge blasting. Using the Mohr–Coulomb yield criterion, we classify the rock failure process into four zones: the cavity zone, fracture zone, radial fracture zone, and vibration zone. Additionally, we establish a dynamic partitioned model that considers explosion cavity expansion, compression wave propagation, and energy dissipation. Applying elastic failure conditions, we develop a calculation model for vibration parameters in each zone and use MATLAB programming to find numerical solutions for the radius of the failure zone, elastic potential energy, and the interface pressure over time. Verification with a granite underground blasting project in Qingdao shows the ratio of the spherical cavity radius to the charge radius is 1.49, and the crushing zone radius to the charge radius is 2.85. Theoretical results are consistent with the approximate method in magnitude and value, confirming the model’s reliability. The interface pressure sharply peaks and then decays exponentially. The growth of the fracture zone depends heavily on initial pressure, rock strength, and Poisson’s ratio. These findings support blasting engineering design and seismic effect assessment. Full article
(This article belongs to the Special Issue Rock Mechanics in Geotechnical and Tunnel Engineering)
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18 pages, 5193 KB  
Article
Destruction Mechanism of Laser Melted Layers of AISI 321 Austenitic Stainless Steel After Electrochemical Corrosion in Ringer’s Solution
by Tsanka Dikova and Natalina Panova
Processes 2025, 13(10), 3116; https://doi.org/10.3390/pr13103116 - 29 Sep 2025
Abstract
The aim of the present study is to investigate the mechanism behind corrosion destruction in laser-melted layers (LMLs) of AISI 321 austenitic stainless steel after electrochemical corrosion in Ringer’s solution. Surface morphology, microstructure, chemical composition, grain sizes, and orientation are studied using OM, [...] Read more.
The aim of the present study is to investigate the mechanism behind corrosion destruction in laser-melted layers (LMLs) of AISI 321 austenitic stainless steel after electrochemical corrosion in Ringer’s solution. Surface morphology, microstructure, chemical composition, grain sizes, and orientation are studied using OM, SEM, EDS, and EBSD. It was confirmed that (1) the main mechanism behind corrosion destruction is identical between untreated and laser-melted steel, i.e., the selective destruction of the lower corrosion resistance phase (δ-ferrite) in the form of pits, and (2) the morphology and size of corrosion pits are different, as determined via δ-ferrite morphology, with narrow deep pits of uneven shape observed on the surface of wrought steel and rounded shallower pits seen in LML. The following mechanism is proposed with regard to corrosion destruction in LML: (1) the initial destruction of δ-ferrite; (2) the formation of an austenitic dendrite network; (3) the mechanical fracture of austenitic dendrites and pit formation; and (4) the growth of pits inside the grain. The following relationship between corrosion pit development and dendrite orientation in the LML is observed: (1) In the melted zone, with dendrite axes perpendicular to or inclined toward the surface, the corrosion pit grows within the grain. (2) At the melted zone/base metal (MZ/BM) boundary, with dendrite axes parallel to the surface, the corrosion pit develops in the heat-affected zone, along the MZ/BM boundary. Full article
(This article belongs to the Special Issue Corrosion Processes of Metals: Mechanisms and Protection Methods)
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18 pages, 5858 KB  
Article
Research on Deformation Behavior and Mechanisms of Concrete Under Hygrothermal Coupling Effects
by Mingyu Li, Chunxiao Zhang, Aiguo Dang, Xiang He, Jingbiao Liu and Xiaonan Liu
Buildings 2025, 15(19), 3514; https://doi.org/10.3390/buildings15193514 - 29 Sep 2025
Abstract
This study elucidated the evolution and catastrophic failure mechanisms of concrete’s mechanical properties under high-temperature and moisture-coupled environments. Specimens underwent hygrothermal shock simulation via constant-temperature drying (100 °C/200 °C, 4 h) followed by water quenching (20 °C, 30 min). Uniaxial compression tests were [...] Read more.
This study elucidated the evolution and catastrophic failure mechanisms of concrete’s mechanical properties under high-temperature and moisture-coupled environments. Specimens underwent hygrothermal shock simulation via constant-temperature drying (100 °C/200 °C, 4 h) followed by water quenching (20 °C, 30 min). Uniaxial compression tests were performed using a uniaxial compression test machine with synchronized multi-scale damage monitoring that integrated digital image correlation (DIC), acoustic emission (AE), and infrared thermography. The results demonstrated that hygrothermal coupling reduced concrete ductility significantly, in which the peak strain decreased from 0.36% (ambient) to 0.25% for both the 100 °C and 200 °C groups, while compressive strength declined to 42.8 MPa (−2.9%) and 40.3 MPa (−8.6%), respectively, with elevated elastic modulus. DIC analysis revealed the temperature-dependent failure mode reconstruction: progressive end cracking (max strain 0.48%) at ambient temperature transitioned to coordinated dual-end cracking with jump-type damage (abrupt principal strain to 0.1%) at 100 °C and degenerated to brittle fracture oriented along a singular path (principal strain band 0.015%) at 200 °C. AE monitoring indicated drastically reduced micro-damage energy barriers at 200 °C, where cumulative energy (4000 mV·ms) plummeted to merely 2% of the ambient group (200,000 mV·ms). Infrared thermography showed that energy aggregation shifted from “centralized” (ambient) to “edge-to-center migration” (200 °C), with intensified thermal shock effects in fracture zones (ΔT ≈ −7.2 °C). The study established that hygrothermal coupling weakens the aggregate-paste interfacial transition zone (ITZ) by concentrating the strain energy along singular weak paths and inducing brittle failure mode degeneration, which thereby provides theoretical foundations for fire-resistant design and catastrophic failure warning systems in concrete structures exposed to coupled environmental stressors. Full article
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21 pages, 3956 KB  
Article
Optimization of Parameters in Multi-Spot Projection Welding of Thin Aluminized Steel Sheets
by Alexandru Vladut Oprea, Robert Catalin Ciocoiu, George Constantin, Carmen Catalina Rusu and Ionelia Voiculescu
Appl. Sci. 2025, 15(19), 10530; https://doi.org/10.3390/app151910530 - 29 Sep 2025
Abstract
Welding is a technological variant of the electric resistance spot-welding process in which the machined protrusion on the surface is heated and rapidly deformed, and the small molten zone formed at the interface is then forged to form the weld spot. The paper [...] Read more.
Welding is a technological variant of the electric resistance spot-welding process in which the machined protrusion on the surface is heated and rapidly deformed, and the small molten zone formed at the interface is then forged to form the weld spot. The paper analyses the effects of projection welding parameter values for thin, low-carbon aluminized steel sheets. Two sets of 16 welded samples having three or five protrusions were performed and analyzed using the Taguchi method. The microstructural aspects were analyzed in cross sections made through the welded points, highlighting the expulsion or accumulated effects of the Al-Si alloy protective layer and the formation of intermetallic compounds. To estimate the effect of welding parameters, the samples were subjected to tensile strength tests, and the fracture mode was evaluated. It was found that the values of the breaking forces were close for the two types of samples analyzed, for identical values of the welding regime parameters, but the elongation at break was double in the case of samples with five protrusions. The breaking force increased from 10.9 kN for samples with three protrusions to 11.4 kN for samples with five protrusions, for the same values of welding parameters. Full article
(This article belongs to the Topic Welding Experiment and Simulation)
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15 pages, 4797 KB  
Article
Overburden Damage in High-Intensity Mining: Effects of Lithology and Formation Structure
by Teng Teng, Zhuhe Xu and Yuxuan Wang
Appl. Sci. 2025, 15(19), 10518; https://doi.org/10.3390/app151910518 - 28 Sep 2025
Abstract
This study addresses pivotal scientific questions regarding the evolution of overburden strata during high-intensity mining in the Shendong coal mining area. Through a comprehensive research methodology combining physical similarity tests and numerical simulations, we systematically quantified the influence of key stratum thickness, key [...] Read more.
This study addresses pivotal scientific questions regarding the evolution of overburden strata during high-intensity mining in the Shendong coal mining area. Through a comprehensive research methodology combining physical similarity tests and numerical simulations, we systematically quantified the influence of key stratum thickness, key stratum location, and mining thickness on overburden damage and fracture propagation dynamics. The results reveal that: (1) The fractal dimension of the fracture network in the damaged overburden ranges from 1.2 to 1.5; a reduction in the thickness of the key layer results in the most severe overburden damage, whereas a decrease in mining height leads to the least damage. (2) A reduction in key stratum thickness accelerates structural failure initiation, expanding rock subsidence area (16.7% increase) while constraining fracture zone vertical development (8.3% reduction). (3) Raising the key stratum position demonstrates dual suppression effects, decreasing both subsidence magnitude (22.4%) and spatial extent (18.6%) of overburden movement. (4) Conversely, a decrease in mining thickness induces the amplified subsidence responses (20% increase), accompanied by enhanced fracture zone vertical propagation. This study provides an important reference for the systematic investigation and comparison of the impacts and prevention strategies associated with high-intensity mining in the Shendong mining area. Full article
(This article belongs to the Special Issue Mining-Induced Rock Strata Damage and Mine Disaster Control)
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33 pages, 10887 KB  
Article
The Analysis of Transient Drilling Fluid Loss in Coupled Drill Pipe-Wellbore-Fracture System of Deep Fractured Reservoirs
by Zhichao Xie, Yili Kang, Xueqiang Wang, Chengyuan Xu and Chong Lin
Processes 2025, 13(10), 3100; https://doi.org/10.3390/pr13103100 - 28 Sep 2025
Abstract
Drilling fluid loss is a common and complex downhole problem that occurs during drilling in deep fractured formations, which has a significant negative impact on the exploration and development of oil and gas resources. Establishing a drilling fluid loss model for the quantitative [...] Read more.
Drilling fluid loss is a common and complex downhole problem that occurs during drilling in deep fractured formations, which has a significant negative impact on the exploration and development of oil and gas resources. Establishing a drilling fluid loss model for the quantitative analysis of drilling fluid loss is the most effective method for the diagnosis of drilling fluid loss, which provides a favorable basis for the formulation of drilling fluid loss control measures, including the information on thief zone location, loss type, and the size of loss channels. The previous loss model assumes that the drilling fluid is driven by constant flow or pressure at the fracture inlet. However, drilling fluid loss is a complex physical process in the coupled wellbore circulation system. The lost drilling fluid is driven by dynamic bottomhole pressure (BHP) during the drilling process. The use of a single-phase model to describe drilling fluids ignores the influence of solid-phase particles in the drilling fluid system on its rheological properties. This paper aims to model drilling fluid loss in the coupled wellbore–-fracture system based on the two-phase flow model. It focuses on the effects of well depth, drilling pumping rate, drilling fluid density, viscosity, fracture geometric parameters, and their morphology on loss during the drilling fluid circulation process. Numerical discrete equations are derived using the finite volume method and the “upwind” scheme. The correctness of the model is verified by published literature data and experimental data. The results show that the loss model without considering the circulation of drilling fluid underestimates the extent of drilling fluid loss. The presence of annular pressure loss in the circulation of drilling fluid will lead to an increase in BHP, resulting in more serious loss. Full article
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28 pages, 7252 KB  
Article
Study on the Deformation Energy Evolution Characteristics and Instability Prediction Model of Weak Surrounding Rock in Tunnels
by Chuang Sun, Zhengyang Xu, Jianjun Zhang, Yunbo Pu, Qi Tao, Ye Zhou, Xibin Guan and Tianhao Liu
Appl. Sci. 2025, 15(19), 10478; https://doi.org/10.3390/app151910478 - 27 Sep 2025
Abstract
This study focuses on tunnel construction in fault fracture zones and systematically investigates the energy evolution and damage catastrophe mechanisms of surrounding rock during excavation, based on energy conservation principles and cusp catastrophe theory. A tunnel instability prediction and support optimization framework integrating [...] Read more.
This study focuses on tunnel construction in fault fracture zones and systematically investigates the energy evolution and damage catastrophe mechanisms of surrounding rock during excavation, based on energy conservation principles and cusp catastrophe theory. A tunnel instability prediction and support optimization framework integrating energy damage evolution and intelligent optimization algorithms was developed. Field tests, rock mechanics experiments, and Discrete Fracture Network (DFN) numerical simulations reveal the intrinsic relationships among energy input, dissipation, damage accumulation, and instability under complex geological conditions. Particle Swarm Optimization–Back Propagation (PSO-BP) is applied to optimize tunnel support parameters. Model performance is evaluated using the Mean Absolute Error (MAE), Mean Squared Error (MSE), Mean Absolute Percentage Error (MAPE), and R-squared (R2). The results show that upon reaching structural mutation zones, the system damage variable (ds), displacement, and dissipated energy increase abruptly, indicating critical instability. Numerical simulation and catastrophe feature analysis demonstrate that energy-related damage accumulation is effectively suppressed, the system damage variable decreases significantly, and crown stability is greatly enhanced. These findings provide a theoretical basis and practical reference for optimizing tunnel support design and controlling instability risks in complex geological settings. Full article
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16 pages, 3355 KB  
Article
Mechanical and Microstructural Investigations of AA2124/SiC Metal Matrix Composites After Creep
by Agnieszka Rutecka, Katarzyna Makowska and Zbigniew Ludwik Kowalewski
Materials 2025, 18(19), 4495; https://doi.org/10.3390/ma18194495 - 27 Sep 2025
Abstract
The AA2124 aluminium alloy-based metal matrix composites (MMCs) reinforced with the silicon carbide (SiC) were examined under tensile creep at 300 °C. The tests were carried out for the materials of different SiC particle size (3 µm and 0.6 µm) and amount (17 [...] Read more.
The AA2124 aluminium alloy-based metal matrix composites (MMCs) reinforced with the silicon carbide (SiC) were examined under tensile creep at 300 °C. The tests were carried out for the materials of different SiC particle size (3 µm and 0.6 µm) and amount (17 vol.% and 25 vol.%). Creep curves under different constant stresses are presented. A high stress sensitivity of the composites tested was identified for a very narrow range of stress values. As a result, a threshold stress range separating the slow and fast creep stages was easily identified at around 5 Mpa for the composite with a larger SiC particle size and lower content and around 1 Mpa for the two other composites. It means that a very small change in stress applied to the structural element at elevated temperatures may lead to its very rapid collapse or even the destruction of the whole structure. The experimental programme was supplemented by the microstructural observations carried out using the scanning electron microscopy providing data necessary for better understanding the damage mechanisms of the material subjected to creep. An influence of voids on the mechanical response and fracture zones was identified. Attention was paid to the nature of degradation of the composites. Full article
(This article belongs to the Special Issue Mechanical Behavior of Advanced Composite Materials and Structures)
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29 pages, 2736 KB  
Article
Damage Assessment and Fatigue Life Prediction in Exhaust Manifolds Through a Unified Method Using the FEM and XFEM
by Nouhaila Ouyoussef, Hassane Moustabchir, Maria Luminita Scutaru and Ovidiu Vasile
Appl. Sci. 2025, 15(19), 10410; https://doi.org/10.3390/app151910410 - 25 Sep 2025
Abstract
This study investigates the structural and fracture behavior of an automotive exhaust manifold with a predefined semi-elliptical surface crack under realistic thermo-mechanical loading. A combined FEM–XFEM workflow was applied; the FEM identified the critical stress concentration zone, where the maximum Von Mises stress [...] Read more.
This study investigates the structural and fracture behavior of an automotive exhaust manifold with a predefined semi-elliptical surface crack under realistic thermo-mechanical loading. A combined FEM–XFEM workflow was applied; the FEM identified the critical stress concentration zone, where the maximum Von Mises stress reached 165.6 MPa at 700 °C, and the XFEM was used to model crack growth with a refined mesh. The computed Mode I stress intensity factors ranged from 21 to 24 MPa√m, remaining below the temperature-dependent fracture toughness of AISI 321 stainless steel, which confirmed stable crack behavior under service conditions. Fatigue life was assessed using the Smith–Watson–Topper (SWT) parameter. Two scenarios were considered: a quasi-pulsating case, giving a predicted life of 3.8 × 108 cycles, and a fully reversed case, reducing the life to 6.7 × 107 cycles. These results confirm that the manifold operates within the high-cycle fatigue regime, while also demonstrating the strong sensitivity of life predictions to the applied stress ratio. This combined FEM–XFEM methodology provides a reliable numerical framework for assessing crack driving forces and guiding durability-based design of exhaust manifolds. Full article
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