A multi-stage stress relaxation test was performed on a granodiorite sample to understand the deformation process prior to the macroscopic failure of brittle rocks,as well as the transient response during stress relax...A multi-stage stress relaxation test was performed on a granodiorite sample to understand the deformation process prior to the macroscopic failure of brittle rocks,as well as the transient response during stress relaxation.Distributed optical fiber sensing was used to measure strains across the sample surface by helically wrapping the single-mode fiber around the cylindrical sample.Close agreement was observed between the circumferential strains obtained from the optical fibers and the extensometer.The reconstructed full-field strain contours show strain heterogeneity from the crack closure phase,and the strains in the later deformation phase are dominantly localized within the former high-strain zone.The Gini coefficient was used to quantify the degree of strain localization and shows an initial increase during the crack closure phase,a decrease during the linear elastic phase,and a subsequent increase during the post-yielding phase.This behavior corresponds to a process of initial localization from an imperfect boundary condition,homogenization,and eventual relocalization prior to the macroscopic failure of the sample.The transient strain rate decay during the stress relaxation phase was quantified using the p-value in the“Omori-like"power law function.A higher initial stress at the onset of relaxation results in a lower p-value,indicating a slower strain rate decay.As the sample approaches macroscopic failure,the lowest p-value shifts from the most damaged zone to adjacent areas,suggesting stress redistribution or crack propagation in deformed crystalline rocks under stress relaxation conditions.展开更多
Catastrophic failure in engineering structures of island reefs would occur when the tertiary creep initiates in coral reef limestone with a transition from short-to long-term load.Due to the complexity of biological s...Catastrophic failure in engineering structures of island reefs would occur when the tertiary creep initiates in coral reef limestone with a transition from short-to long-term load.Due to the complexity of biological structures,the underlying micro-behaviors involving time-dependent deformation are poorly understood.For this,an abnormal phenomenon was observed where the axial and lateral creep deformations were mutually independent by a series of triaxial tests under constant stress and strain rate conditions.The significantly large lateral creep deformation implies that the creep process cannot be described in continuum mechanics regime.Herein,it is hypothesized that sliding mechanism of crystal cleavages dominates the lateral creep deformation in coral reef limestone.Then,approaches of polarizing microscope(PM)and scanning electronic microscope(SEM)are utilized to validate the hypothesis.It shows that the sliding behavior of crystal cleavages combats with conventional creep micro-mechanisms at certain condition.The former is sensitive to time and strain rate,and is merely activated in the creep regime.展开更多
Excavation and control of tunneling responses in swelling soft-rock tunnels of Sichuan-Xizang railway under seepage conditions were studied.For this,a fractional viscoplastic(FVP)model for swelling soft rocks was esta...Excavation and control of tunneling responses in swelling soft-rock tunnels of Sichuan-Xizang railway under seepage conditions were studied.For this,a fractional viscoplastic(FVP)model for swelling soft rocks was established by introducing Abel dashpot and unsteady viscosity coefficient,considering additional swelling deformation and damage of rock caused by humidity effect.In view of the FVP model,the viscoplastic deformation solutions for rock mass surrounding tunnel under seepage conditions were derived and long-term mechanical responses of swelling rocks upon tunnel excavation were analyzed.Next,a stress release coefficient considering seepage and creep was proposed,based on which control responses considering stress release and failure mechanism of stress release measures were analyzed.The results showed that:(i)The one-dimensional(1D)FVP model has a good application for swelling rock and the three-dimensional(3D)FVP model could well describe the whole creep process of rock mass despite a much higher creep attenuation rate in the first stage of creep;and(ii)An appropriate stress release and deformation of surrounding rocks could effectively reduce the supporting resistance.However,upon a large stress release,the radius of plastic region could increase significantly,and the strength of the surrounding rock mass decreases greatly.The proposed solution could provide a theoretical framework for capturing the excavation and support responses for tunneling in swelling rock mass in consideration of time effect.展开更多
A new experimental approach to assess the impact of soil confinement on the long-term behavior of geosynthetics is presented in this paper.The experimental technique described herein includes a novel laboratory appara...A new experimental approach to assess the impact of soil confinement on the long-term behavior of geosynthetics is presented in this paper.The experimental technique described herein includes a novel laboratory apparatus and the use of different types of tests that allow generation of experimental data suitable for evaluation of the time-dependent behavior of geosynthetics under soil confinement.The soil-geosynthetic interaction equipment involves a rigid box capable of accommodating a cubic soil mass under plane strain conditions.A geosynthetic specimen placed horizontally at the mid-height of the soil mass is subjected to sustained vertical pressures that,in turn,induce reinforcement axial loads applied from the soil to the geosynthetic.Unlike previously reported studies on geosynthetic behavior under soil confinement,the equipment was found to be particularly versatile.With minor setup modifications,not only interaction tests but also in-isolation geosynthetic stress relaxation tests and soil-only tests under a constant strain rate can be conducted using the same device.Also,the time histories of the reinforcement loads and corresponding strains are generated throughout the test.Results from typical tests conducted using sand and a polypropylene woven geotextile are presented to illustrate the proposed experimental approach.The testing procedure was found to provide adequate measurements during tests,including good repeatability of test results.The soilegeosynthetic interaction tests were found to lead to increasing geotextile strains with time and decreasing reinforcement tension with time.The test results highlighted the importance of measuring not only the time history of displacements but also that of reinforcement loads during testing.The approach of using different types of tests to analyze the soilegeosynthetic interaction behavior is an innovation that provides relevant insight into the impact of soil confinement on the time-dependent deformations of geosynthetics.展开更多
The hot compression deformation behavior of Mg-6Zn-1Mn-0.5Ca(ZM61-0.5Ca)and Mg-6Zn-1Mn-2Sn-0.5Ca(ZMT612-0.5Ca)alloys was investigated at deformation temperatures ranging from 250℃to 400℃and strain rates varying from...The hot compression deformation behavior of Mg-6Zn-1Mn-0.5Ca(ZM61-0.5Ca)and Mg-6Zn-1Mn-2Sn-0.5Ca(ZMT612-0.5Ca)alloys was investigated at deformation temperatures ranging from 250℃to 400℃and strain rates varying from 0.001 s^(-1) to 1 s^(-1).The results show that the addition of Sn promotes dynamic recrystallization(DRX),and CaMgSn phases can act as nucleation sites during the compression deformation.Flow stress increases with increasing the strain rate and decreasing the temperature.Both the ZM61-0.5Ca and ZMT612-0.5Ca alloys exhibit obvious DRX characteristics.CaMgSn phases can effectively inhibit dislocation motion with the addition of Sn,thus increasing the peak fl ow stress of the alloy.The addition of Sn increases the hot deformation activation energy of the ZM61-0.5Ca alloy from 199.654 kJ/mol to 276.649 kJ/mol,thus improving the thermal stability of the alloy.For the ZMT612-0.5Ca alloy,the optimal hot deformation parameters are determined to be a deformation temperature range of 350–400℃and a strain rate range of 0.001–0.01 s^(-1).展开更多
The strength and damping properties of Co-Ni-Cr-Mo-based alloys with 0.5wt%Nb addition after various plastic deformation and heat treatment processes were investigated.Through Vickers hardness tests,free resonance You...The strength and damping properties of Co-Ni-Cr-Mo-based alloys with 0.5wt%Nb addition after various plastic deformation and heat treatment processes were investigated.Through Vickers hardness tests,free resonance Young's modulus measurements,and microstructure analysis,the effects of dislocation density,vacancy formation,and recrystallization on the alloy performance were clarified.Results indicate that increasing the rolling reduction enhances damping property due to higher dislocation density,whereas aging below the recrystallization temperature reduces damping property via dislocation pinning by the Suzuki effect.Recrystallization heat treatment restores the original structure and damping level.This alloy possesses tensile strength of approximately 1500 MPa and logarithmic decrement valueδ^(-1) in the range of 2×10^(-4)–3×10^(-4),demonstrating superior mechanical properties compared with the Ti-based alloys,which makes it an excellent candidate material for ultrasonic tools and medical applications.展开更多
The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing t...The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.展开更多
Backfill is routinely adopted as a ground support measure for underground mines.However,ground stability enhancement by backfill has received limited research attention.This is likely to be because of the conventional...Backfill is routinely adopted as a ground support measure for underground mines.However,ground stability enhancement by backfill has received limited research attention.This is likely to be because of the conventional assumption that the fill material exhibits a significantly lower stiffness than the host rocks.Significantly,a recent pioneering work revealed the time-dependent ground stability around a backfilled stope with vertical walls through numerical modeling.In practice,underground stopes typically exhibit a higher or lower degree of inclination.This alters the stress state in peripheral rocks and may induce severe instability and dilution,particularly in stope-hanging walls.Hence,it is imperative to analyze the time-dependent ground stability of inclined backfilled stopes for backfill structure design.Therefore,comprehensive numerical simulations were performed using FLAC3D to address this knowledge deficiency by incorporating a coupled analysis of the backfill consolidation behavior and long-term creep deformation in surrounding rocks.The ground stability was evaluated based on the confinement effectiveness,strength-stress ratio,stress path relative to the yield surface,and time-dependent stress redistribution in the rocks.A parametric study revealed that the inclination angle of the backfilled stope reduced the confinement effectiveness in the host rocks when the wall creep was minor.This exacerbated the rock mass sloughing potential.However,a backfilled stope with a shallower dip angle achieved superior ground stability enhancement when the creep deformation was substantial,by applying a more significant compression on the backfill and effectively mobilizing its passive support performance during consolidation.Additional simulations were conducted to analyze the effects of stope height and width,mine depth,mechanical properties of rocks,backfill compressibility,and filling gap on the time-dependent stress redistribution and stability around the inclined backfilled stope.展开更多
In deep coal mining,surrounding rock is subjected to both high in-situ stress and intense mining disturbances,leading to significant time-dependent behavior.Accurately capturing this behavior is essential for predicti...In deep coal mining,surrounding rock is subjected to both high in-situ stress and intense mining disturbances,leading to significant time-dependent behavior.Accurately capturing this behavior is essential for predicting long-term roadway stability,necessitating the development of a reliable constitutive creep model and numerical simulation approach.In this study,creep experiments were conducted on pre-damaged rock with varying initial damage levels to investigate the time-dependent mechanical properties.Based on the experimental results,an accelerated-creep criterion was proposed,and an elastic-viscoplastic creep damage model(EVPCD)was established that simultaneously considers the effects of time-dependent damage and instantaneous damage caused by stress disturbances on rock creep behavior.Subsequently,the effectiveness of the proposed creep model was verified using experimental data,and the secondary development of the EVPCD model was completed based on the FLAC3D platform.Following this,a long-term stability analysis method of deep surrounding rock that accounts for excavation-and mining-induced disturbances was proposed.Using the main roadway of Xutuan Coal Mine as a case study,numerical simulations were carried out to investigate the time-dependent deformation and failure characteristics of the surrounding rock following excavation and mining disturbance.Combined with on-site monitoring of the surrounding rock damage areas,the results indicate that the EVPCD outperforms the CVISC and Nishihara models in predicting the time-dependent behavior of deep surrounding rock.展开更多
Quantitative assessment of microscale slip activities and plastic localizations is essential for understanding the complex deformation mechanisms in crystalline materials.However,few experimental studies have been abl...Quantitative assessment of microscale slip activities and plastic localizations is essential for understanding the complex deformation mechanisms in crystalline materials.However,few experimental studies have been able to dynamically measure the deformation fields of rapidly evolving slip activities at the microscale.In this study,we used the Sampling Moire?Method(SMM)to directly measure the dynamic deformation fields of slip activities in Nickel-Based Single-Crystal(NBSC)superalloy under in-situ tensile test,and the strain and displacement fields under the evolving microplastic events with intense slip activities around the notch of the NBSC superalloy specimen were obtained for the first time.The dynamic evolution of slip bands was quantitatively characterized through detailed statistical analysis of strains and displacements under different loads.The locations of the initial appearance of slip traces were successfully predicted by the regions of plasticity localization.The results show that the deformation fields exhibit both high spatial and temporal resolutions,enabling the capture of nanometer-scale displacement fields and visualization of the dynamic fluidity of slip accumulation.This method demonstrates the superiority of the dynamic characterization of the plastic deformation field at the microscale and the promise of its application for characterizing the slip activities of various crystalline metals.展开更多
A Hybrid Free-Form Deformation(HFFD)method is developed to improve shape preservation in mesh deformation for perforated surfaces,which traditional Free-Form Deformation(FFD)techniques struggle to handle effectively.T...A Hybrid Free-Form Deformation(HFFD)method is developed to improve shape preservation in mesh deformation for perforated surfaces,which traditional Free-Form Deformation(FFD)techniques struggle to handle effectively.The proposed method enables high-fidelity parameterized deformation for both flat and curved perforated surfaces while maintaining mesh quality with minimal geometric distortion.To evaluate its effectiveness,comparative studies between HFFD and conventional FFD methods are conducted,demonstrating superior performance in mesh quality and geometric fidelity.The HFFD-based framework is further applied to the Multidisciplinary Design Optimization(MDO)of a double-wall turbine blade leading edge.Results indicate an 11.6%increase in cooling efficiency and a 16.21%reduction in maximum stress.Additionally,compared to traditional geometry-based parameterization in MDO,the HFFD approach improves model processing efficiency by 84.15%and overall optimization efficiency by20.05%.These findings demonstrate HFFD's potential to significantly improve complex engineering design optimization by achieving precise shape preservation and improving computational efficiency.展开更多
The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread att...The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread attention from researchers.In this paper,the deformation and buckling behaviors of a circular arch subject to compression by a rigid plate are investigated with a planar elastic rod model that incorporates tension,shearing,and bending.In comparison with the existing models that solely consider the bending energy,the deflection curve,the internal force distribution,and the critical load of the present model show good agreement with the finite element results.Through the dimensional analysis and order-of-magnitude estimation,we examine the factors influencing the critical load.The study reveals that the semi-central angle of the arch has the most significant effect.The dimensionless geometric parameter describing arch slenderness becomes prominent when the semi-central angle is less than 30°,while Poisson's ratio and the cross-sectional shear correction factor exhibit negligible influence.Furthermore,the variation in the proportions of strain energy components during critical buckling is presented with respect to the semi-central angle and the geometric parameter,thereby delineating the applicable ranges of both the original model(OM)and the modified model(MM).展开更多
This study presents an implicit multiphysics coupling method integrating Computational Fluid Dynamics(CFD),the Multiphase Particle-in-Cell(MPPIC)model,and the Finite Element Method(FEM),implemented with OpenFOAM,Calcu...This study presents an implicit multiphysics coupling method integrating Computational Fluid Dynamics(CFD),the Multiphase Particle-in-Cell(MPPIC)model,and the Finite Element Method(FEM),implemented with OpenFOAM,CalculiX,and preCICE to simulate fluid-particle-structure interactions with large deformations.Mesh motion in the fluid field is handled using the radial basis function(RBF)method.The particle phase is modeled by MPPIC,where fluid-particle interaction is described through momentum exchange,and inter-particle collisions are characterized by collision stress.The structural field is solved by nonlinear FEM to capture large deformations induced by geometric nonlinearity.Coupling among fields is realized through a partitioned,parallel,and non-intrusive iterative strategy,ensuring stable transfer and convergence of interface forces and displacements.Notably,the influence of particles on the structure is not direct but mediated by the fluid,while structural motion directly affects particle dynamics.The results demonstrate that the proposed approach effectively captures multiphysics interaction processes and provides a valuable reference for numerical modeling of coupled fluid-particle-structure systems.展开更多
Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted dru...Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted drug delivery.For implants,mechanical properties are key performance characteristics,so understanding the deformation and failure mechanisms is essential for selecting the appropriate implant structure.The deformation and fracture processes in PLA samples with different interior architectures have been studied through computer simulation and experimental research.Two TPMS topologies,the Schwarz Diamond and Gyroid architectures,were used for the sample construction by 3D printing.ANSYS software was utilized to simulate compressive deformation.It was found that under the same load,the vonMises stresses in the Gyroid structure are higher than those in the Schwartz Diamond structure,which was associated with the different orientations of the cells in the studied structures in relation to the direction of the loading axis.The deformation process occurs in the local regions of the studied TPMS structures.Maximum von Mises stresses were observed in the vertical parts of the structures oriented along the load direction.It was found that,unlike the Gyroid,the Schwartz Diamond structure contains a frame that forms unique stiffening ribs,which ensures the redistribution of the load under the vertical loading direction.An analysis of the mechanical characteristics of PLA samples with the Schwartz Diamond and Gyroid structures produced by the Fused Deposition Modeling(FDM)method was correlated with computer simulation.The Schwarz Diamond-type structure was shown to have a higher absorption energy than the Gyroid one.A study of the fracture in PLA samples with various cell sizes revealed a particular feature related to the samples’periodic surface topology and the 3D printing process.Scanning electron microscopic(SEM)studies of the samples deformed by compression showed thatwith an increase in the density of the samples,the failure mechanism changes from ductile to quasi-brittle due to the complex participation of both cell deformation and fiber deformation.展开更多
Slopes are likely to fail in areas with frequent rainfall and earthquakes.The deformation characteristics of unsaturated slopes subjected to post-rainfall earthquakes are investigated using centrifuge model tests and ...Slopes are likely to fail in areas with frequent rainfall and earthquakes.The deformation characteristics of unsaturated slopes subjected to post-rainfall earthquakes are investigated using centrifuge model tests and finite element analyses.Three tests of the slope deformation under earthquake and post-rainfall earthquakes are first studied using image analysis techniques.Then,based on an elastoplastic constitutive model,numerical simulations are carried out using the finite element method and compared with the centrifuge test results.Finally,a parametric study is performed to clarify the effects of antecedent rainfall on earthquake-induced slope deformation.The results show that slope deformation caused by post-rainfall earthquakes differs from that caused by earthquakes without antecedent rainfall.The seepage flow and soil strength of the slope are affected by previous rainfall conditions,such as intensity and duration,which directly influence the slope deformation caused by the subsequent earthquake.Soil displacement and strain become greater and the slip surface is more noticeable during the post-rainfall earthquake of higher intensity.In addition,the time interval between the rainfall and the earthquake has a considerable impact on the detailed characteristics of the slope deformation,and the significant deformation occurs at the time of lowest soil strength when seepage flow reaches the lower part of the slope.Moreover,the repeated intermittent rainfall greatly affects the subsequent earthquake-induced slope deformation,the main characteristics of which are closely related to the changes in saturation and strength of the slope.However,with the prolonged time gap between each round of rainfall,the earthquake-induced slope deformation becomes insignificant.展开更多
Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic ...Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic deformation in seawater.In this study,we performed a comparative analysis of the UHMWPE dynamics under seawater and water conditions to investigate the plastic deformation of UHMWPE induced by seawater.The results show that the plastic deformation of UHMWPE is amplified in seawater relative to the water conditions.Under thin fluid conditions,frictional interfaces exhibit a higher interfacial friction force and interaction energy in seawater than in water.Compared to freely diffused water molecules,hydrated ions occupy larger interchain spaces within polyethylene.Furthermore,the diffusion of hydrated ions weakens the interchain interactions,promoting more severe polyethylene chain rearrangement and accelerating seawater-induced plastic deformation in UHMWPE during friction.Furthermore,the diffused seawater accelerated the disentangling of the polyethylene chains and enhanced the orderly orientation distribution of polyethylene.Compared to free water molecules,the water molecules of hydrated ions exhibit enhanced attraction to free-flowing water molecules,thereby accelerating seawater flow across submerged UHMWPE surfaces.This flow enhancement promotes surface polyethylene chain mobility in seawater.展开更多
Understanding the temperature dependent deformation behavior of Mg alloys is crucial for their expanding use in the aerospace sector.This study investigates the deformation mechanisms of hot-rolled AZ61 Mg alloy under...Understanding the temperature dependent deformation behavior of Mg alloys is crucial for their expanding use in the aerospace sector.This study investigates the deformation mechanisms of hot-rolled AZ61 Mg alloy under uniaxial tension along rolling direction(RD)and transverse direction(TD)at-50,25,50,and 150℃.Results reveal a transition from high strength with limited elongation at-50℃ to significant softening and maximum ductility at 150℃.TD samples consistently showed 2%-6%higher strength than RD;however,this yield anisotropy diminished at 150℃ due to the shift from twinning to thermally activated slip and recovery.Fractography indicated a change from semi-brittle to fully ductile fracture with increasing temperature.Electron backscattered diffraction(EBSD)analysis confirmed twinning-driven grain refinement at low temperatures,while deformation at high temperatures involved grain elongation along shear zones,enabling greater strain accommodation before material failure.展开更多
In-situ stress is a key parameter for underground mine design and rock stability analysis.The borehole overcoring technique is widely used for in-situ stress measurement,but the rheological recovery deformation of roc...In-situ stress is a key parameter for underground mine design and rock stability analysis.The borehole overcoring technique is widely used for in-situ stress measurement,but the rheological recovery deformation of rocks after stress relief introduces errors.To improve accuracy,this study proposes an in-situ stress solution theory that incorporates time-dependent stress relief effects.Triaxial stepwise loadingunloading rheological tests on granite and siltstone established quantitative relationships between instantaneous elastic recovery and viscoelastic recovery under different stress levels,confirming their impact on measurement accuracy.By integrating a dual-class elastic deformation recovery model,an improved in-situ stress solution theory was derived.Additionally,accounting for the nonlinear characteristics of rock masses,a determination method for time-dependent nonlinear mechanical parameters was proposed.Based on the CSIRO hollow inclusion strain cell,time-dependent strain correction equations and long-term confining pressure calibration equations were formulated.Finally,the proposed theory was successfully applied at one iron mine(736 m depth)in Xinjiang,China,and one coal mine(510 m depth)in Ningxia,China.Compared to classical theory,the calculated mean stress values showed accuracy improvements of 6.0%and 9.4%,respectively,validating the applicability and reliability of the proposed theory.展开更多
Deformation prediction for extra-high arch dams is highly important for ensuring their safe operation.To address the challenges of complex monitoring data,the uneven spatial distribution of deformation,and the constru...Deformation prediction for extra-high arch dams is highly important for ensuring their safe operation.To address the challenges of complex monitoring data,the uneven spatial distribution of deformation,and the construction and optimization of a prediction model for deformation prediction,a multipoint ultrahigh arch dam deformation prediction model,namely,the CEEMDAN-KPCA-GSWOA-KELM,which is based on a clustering partition,is pro-posed.First,the monitoring data are preprocessed via variational mode decomposition(VMD)and wavelet denoising(WT),which effectively filters out noise and improves the signal-to-noise ratio of the data,providing high-quality input data for subsequent prediction models.Second,scientific cluster partitioning is performed via the K-means++algorithm to precisely capture the spatial distribution characteristics of extra-high arch dams and ensure the consistency of deformation trends at measurement points within each partition.Finally,CEEMDAN is used to separate monitoring data,predict and analyze each component,combine the KPCA(Kernel Principal Component Analysis)and the KELM(Kernel Extreme Learning Machine)optimized by the GSWOA(Global Search Whale Optimization Algorithm),integrate the predictions of each component via reconstruction methods,and precisely predict the overall trend of ultrahigh arch dam deformation.An extra high arch dam project is taken as an example and validated via a comparative analysis of multiple models.The results show that the multipoint deformation prediction model in this paper can combine data from different measurement points,achieve a comprehensive,precise prediction of the deformation situation of extra high arch dams,and provide strong technical support for safe operation.展开更多
Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study el...Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study elucidates the fundamental mechanisms of ultrafast laser shock imprinting(LSI)in two-dimensional tellurium(Te),establishing a direct relationship between strain field orientation,mold topology,and anisotropic structural evolution.This is the first demonstration of ultrafast LSI on chiral chain Te unveiling orientation-sensitive dislocation networks.By applying controlled strain fields parallel or transverse to Te’s helical chains,we uncover two distinct deformation regimes.Strain aligned parallel to the chain’s direction induces gliding and rotation governed by weak interchain interactions,preserving covalent intrachain bonds and vibrational modes.In contrast,transverse strain drives shear-mediated multimodal deformations—tensile stretching,compression,and bending—resulting in significant lattice distortions and electronic property modulation.We discovered the critical role of mold topology on deformation:sharp-edged gratings generate localized shear forces surpassing those from homogeneous strain fields via smooth CD molds,triggering dislocation tangle formation,lattice reorientation,and inhomogeneous plastic deformation.Asymmetrical strain configurations enable localized structural transformations while retaining single-crystal integrity in adjacent regions—a balance essential for functional device integration.These insights position LSI as a precision tool for nanoscale strain engineering,capable of sculpting 2D material morphologies without compromising crystallinity.By bridging ultrafast mechanics with chiral chain material science,this work advances the design of strain-tunable devices for next-generation electronics and optoelectronics,while establishing a universal framework for manipulating anisotropic 2D systems under extreme strain rates.This work discovered crystallographic orientation-dependent deformation mechanisms in 2D Te,linking parallel strain to chain gliding and transverse strain to shear-driven multimodal distortion.It demonstrates mold geometry as a critical lever for strain localization and dislocation dynamics,with sharp-edged gratings enabling unprecedented control over lattice reorientation.Crucially,the identification of strain field conditions that reconcile severe plastic deformation with single-crystal retention offers a pathway to functional nanostructure fabrication,redefining LSI’s potential in ultrafast strain engineering of chiral chain materials.展开更多
基金support of her postdoctoral research at the GFZ Helmholtz Centre for Geosciences.P.Pan acknowledges the financial support of the National Natural Science Foundation of China(Grant No.52339001)H.Hofmann and Y.Ji acknowledge the financial support of the Helmholtz Association's Initiative and Networking Fund for the Helmholtz Young Investigator Group ARES(contract number VH-NG-1516).
文摘A multi-stage stress relaxation test was performed on a granodiorite sample to understand the deformation process prior to the macroscopic failure of brittle rocks,as well as the transient response during stress relaxation.Distributed optical fiber sensing was used to measure strains across the sample surface by helically wrapping the single-mode fiber around the cylindrical sample.Close agreement was observed between the circumferential strains obtained from the optical fibers and the extensometer.The reconstructed full-field strain contours show strain heterogeneity from the crack closure phase,and the strains in the later deformation phase are dominantly localized within the former high-strain zone.The Gini coefficient was used to quantify the degree of strain localization and shows an initial increase during the crack closure phase,a decrease during the linear elastic phase,and a subsequent increase during the post-yielding phase.This behavior corresponds to a process of initial localization from an imperfect boundary condition,homogenization,and eventual relocalization prior to the macroscopic failure of the sample.The transient strain rate decay during the stress relaxation phase was quantified using the p-value in the“Omori-like"power law function.A higher initial stress at the onset of relaxation results in a lower p-value,indicating a slower strain rate decay.As the sample approaches macroscopic failure,the lowest p-value shifts from the most damaged zone to adjacent areas,suggesting stress redistribution or crack propagation in deformed crystalline rocks under stress relaxation conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.41877267,41877260)the Priority Research Program of the Chinese Academy of Science(Grant No.XDA13010201).
文摘Catastrophic failure in engineering structures of island reefs would occur when the tertiary creep initiates in coral reef limestone with a transition from short-to long-term load.Due to the complexity of biological structures,the underlying micro-behaviors involving time-dependent deformation are poorly understood.For this,an abnormal phenomenon was observed where the axial and lateral creep deformations were mutually independent by a series of triaxial tests under constant stress and strain rate conditions.The significantly large lateral creep deformation implies that the creep process cannot be described in continuum mechanics regime.Herein,it is hypothesized that sliding mechanism of crystal cleavages dominates the lateral creep deformation in coral reef limestone.Then,approaches of polarizing microscope(PM)and scanning electronic microscope(SEM)are utilized to validate the hypothesis.It shows that the sliding behavior of crystal cleavages combats with conventional creep micro-mechanisms at certain condition.The former is sensitive to time and strain rate,and is merely activated in the creep regime.
基金Authors are thankful to Dr.Chen Xu of Ningbo University for his instructive discussions.The authors are also grateful for the support provided by the National Natural Science Foundation of China(Grant Nos.41972274 and 42207176)Ningbo Natural Science Foundation(Grant No.2022J116)for this research work.
文摘Excavation and control of tunneling responses in swelling soft-rock tunnels of Sichuan-Xizang railway under seepage conditions were studied.For this,a fractional viscoplastic(FVP)model for swelling soft rocks was established by introducing Abel dashpot and unsteady viscosity coefficient,considering additional swelling deformation and damage of rock caused by humidity effect.In view of the FVP model,the viscoplastic deformation solutions for rock mass surrounding tunnel under seepage conditions were derived and long-term mechanical responses of swelling rocks upon tunnel excavation were analyzed.Next,a stress release coefficient considering seepage and creep was proposed,based on which control responses considering stress release and failure mechanism of stress release measures were analyzed.The results showed that:(i)The one-dimensional(1D)FVP model has a good application for swelling rock and the three-dimensional(3D)FVP model could well describe the whole creep process of rock mass despite a much higher creep attenuation rate in the first stage of creep;and(ii)An appropriate stress release and deformation of surrounding rocks could effectively reduce the supporting resistance.However,upon a large stress release,the radius of plastic region could increase significantly,and the strength of the surrounding rock mass decreases greatly.The proposed solution could provide a theoretical framework for capturing the excavation and support responses for tunneling in swelling rock mass in consideration of time effect.
基金This paper is dedicated to Benedito Bueno(in memoriam),a brilliant researcher and former professor at University of São Paulo,to whom the authors are indebted for his vision and enormous contribution during the development of this work.This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(CAPES),Brazil(finance code 001).
文摘A new experimental approach to assess the impact of soil confinement on the long-term behavior of geosynthetics is presented in this paper.The experimental technique described herein includes a novel laboratory apparatus and the use of different types of tests that allow generation of experimental data suitable for evaluation of the time-dependent behavior of geosynthetics under soil confinement.The soil-geosynthetic interaction equipment involves a rigid box capable of accommodating a cubic soil mass under plane strain conditions.A geosynthetic specimen placed horizontally at the mid-height of the soil mass is subjected to sustained vertical pressures that,in turn,induce reinforcement axial loads applied from the soil to the geosynthetic.Unlike previously reported studies on geosynthetic behavior under soil confinement,the equipment was found to be particularly versatile.With minor setup modifications,not only interaction tests but also in-isolation geosynthetic stress relaxation tests and soil-only tests under a constant strain rate can be conducted using the same device.Also,the time histories of the reinforcement loads and corresponding strains are generated throughout the test.Results from typical tests conducted using sand and a polypropylene woven geotextile are presented to illustrate the proposed experimental approach.The testing procedure was found to provide adequate measurements during tests,including good repeatability of test results.The soilegeosynthetic interaction tests were found to lead to increasing geotextile strains with time and decreasing reinforcement tension with time.The test results highlighted the importance of measuring not only the time history of displacements but also that of reinforcement loads during testing.The approach of using different types of tests to analyze the soilegeosynthetic interaction behavior is an innovation that provides relevant insight into the impact of soil confinement on the time-dependent deformations of geosynthetics.
基金Sichuan Science and Technology Program(2025ZNSFSC1341)Fundamental Research Funds for the Central Universities(J2022-090,25CAFUC04087)。
文摘The hot compression deformation behavior of Mg-6Zn-1Mn-0.5Ca(ZM61-0.5Ca)and Mg-6Zn-1Mn-2Sn-0.5Ca(ZMT612-0.5Ca)alloys was investigated at deformation temperatures ranging from 250℃to 400℃and strain rates varying from 0.001 s^(-1) to 1 s^(-1).The results show that the addition of Sn promotes dynamic recrystallization(DRX),and CaMgSn phases can act as nucleation sites during the compression deformation.Flow stress increases with increasing the strain rate and decreasing the temperature.Both the ZM61-0.5Ca and ZMT612-0.5Ca alloys exhibit obvious DRX characteristics.CaMgSn phases can effectively inhibit dislocation motion with the addition of Sn,thus increasing the peak fl ow stress of the alloy.The addition of Sn increases the hot deformation activation energy of the ZM61-0.5Ca alloy from 199.654 kJ/mol to 276.649 kJ/mol,thus improving the thermal stability of the alloy.For the ZMT612-0.5Ca alloy,the optimal hot deformation parameters are determined to be a deformation temperature range of 350–400℃and a strain rate range of 0.001–0.01 s^(-1).
文摘The strength and damping properties of Co-Ni-Cr-Mo-based alloys with 0.5wt%Nb addition after various plastic deformation and heat treatment processes were investigated.Through Vickers hardness tests,free resonance Young's modulus measurements,and microstructure analysis,the effects of dislocation density,vacancy formation,and recrystallization on the alloy performance were clarified.Results indicate that increasing the rolling reduction enhances damping property due to higher dislocation density,whereas aging below the recrystallization temperature reduces damping property via dislocation pinning by the Suzuki effect.Recrystallization heat treatment restores the original structure and damping level.This alloy possesses tensile strength of approximately 1500 MPa and logarithmic decrement valueδ^(-1) in the range of 2×10^(-4)–3×10^(-4),demonstrating superior mechanical properties compared with the Ti-based alloys,which makes it an excellent candidate material for ultrasonic tools and medical applications.
基金National Key R&D Program of China(2023YFB3711904,2022YFA1603801)National Natural Science Foundation of China(12404230,52471181,52301213,52130108,52471005)+2 种基金National Nature Science Foundation of Zhejiang Province(LY23E010002)Open Fund of the China Spallation Neutron Source,Songshan Lake Science City(KFKT2023B11)Guangdong Basic and Applied Basic Research Foundation(2022A1515110805,2024A1515010878)。
文摘The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.
基金funding support from the National Natural Science Foundation of China(Nos.52304101 and 52204153)the China Postdoctoral Science Foundation(No.2023MD734215)+2 种基金the Youth Talent Support Program of Xi’an Association for Science and Technology(No.959202413070)the Key Research and Development Program of Shaanxi(No.2023-LL-QY-07)the Key Research and Development Program of Zhejiang(No.2023C03182).
文摘Backfill is routinely adopted as a ground support measure for underground mines.However,ground stability enhancement by backfill has received limited research attention.This is likely to be because of the conventional assumption that the fill material exhibits a significantly lower stiffness than the host rocks.Significantly,a recent pioneering work revealed the time-dependent ground stability around a backfilled stope with vertical walls through numerical modeling.In practice,underground stopes typically exhibit a higher or lower degree of inclination.This alters the stress state in peripheral rocks and may induce severe instability and dilution,particularly in stope-hanging walls.Hence,it is imperative to analyze the time-dependent ground stability of inclined backfilled stopes for backfill structure design.Therefore,comprehensive numerical simulations were performed using FLAC3D to address this knowledge deficiency by incorporating a coupled analysis of the backfill consolidation behavior and long-term creep deformation in surrounding rocks.The ground stability was evaluated based on the confinement effectiveness,strength-stress ratio,stress path relative to the yield surface,and time-dependent stress redistribution in the rocks.A parametric study revealed that the inclination angle of the backfilled stope reduced the confinement effectiveness in the host rocks when the wall creep was minor.This exacerbated the rock mass sloughing potential.However,a backfilled stope with a shallower dip angle achieved superior ground stability enhancement when the creep deformation was substantial,by applying a more significant compression on the backfill and effectively mobilizing its passive support performance during consolidation.Additional simulations were conducted to analyze the effects of stope height and width,mine depth,mechanical properties of rocks,backfill compressibility,and filling gap on the time-dependent stress redistribution and stability around the inclined backfilled stope.
基金funded by the National Natural Science Foundation of China(Nos.52004098,U24B2041,and 52274079)the Key Research and Development Program of Henan Province(No.251111320400)+1 种基金the Key Research Project Plan for Higher Education Institutions in Henan Province(Nos.24A570006 and 25A570002)the Scientific and Technological Research Project in Henan Province(No.242102320061).
文摘In deep coal mining,surrounding rock is subjected to both high in-situ stress and intense mining disturbances,leading to significant time-dependent behavior.Accurately capturing this behavior is essential for predicting long-term roadway stability,necessitating the development of a reliable constitutive creep model and numerical simulation approach.In this study,creep experiments were conducted on pre-damaged rock with varying initial damage levels to investigate the time-dependent mechanical properties.Based on the experimental results,an accelerated-creep criterion was proposed,and an elastic-viscoplastic creep damage model(EVPCD)was established that simultaneously considers the effects of time-dependent damage and instantaneous damage caused by stress disturbances on rock creep behavior.Subsequently,the effectiveness of the proposed creep model was verified using experimental data,and the secondary development of the EVPCD model was completed based on the FLAC3D platform.Following this,a long-term stability analysis method of deep surrounding rock that accounts for excavation-and mining-induced disturbances was proposed.Using the main roadway of Xutuan Coal Mine as a case study,numerical simulations were carried out to investigate the time-dependent deformation and failure characteristics of the surrounding rock following excavation and mining disturbance.Combined with on-site monitoring of the surrounding rock damage areas,the results indicate that the EVPCD outperforms the CVISC and Nishihara models in predicting the time-dependent behavior of deep surrounding rock.
基金supported by the Natural Science Foundation of China(No.12372176)the National Science and Technology Major Project of China(No.J2019-IV-0007-0075)。
文摘Quantitative assessment of microscale slip activities and plastic localizations is essential for understanding the complex deformation mechanisms in crystalline materials.However,few experimental studies have been able to dynamically measure the deformation fields of rapidly evolving slip activities at the microscale.In this study,we used the Sampling Moire?Method(SMM)to directly measure the dynamic deformation fields of slip activities in Nickel-Based Single-Crystal(NBSC)superalloy under in-situ tensile test,and the strain and displacement fields under the evolving microplastic events with intense slip activities around the notch of the NBSC superalloy specimen were obtained for the first time.The dynamic evolution of slip bands was quantitatively characterized through detailed statistical analysis of strains and displacements under different loads.The locations of the initial appearance of slip traces were successfully predicted by the regions of plasticity localization.The results show that the deformation fields exhibit both high spatial and temporal resolutions,enabling the capture of nanometer-scale displacement fields and visualization of the dynamic fluidity of slip accumulation.This method demonstrates the superiority of the dynamic characterization of the plastic deformation field at the microscale and the promise of its application for characterizing the slip activities of various crystalline metals.
基金supported by the National Science and Technology Major Project,China(No.2017-II-0006-0019)the National Natural Science Foundation of China(No.52375266)the Shaanxi Science Foundation for Distinguished Young Scholars,China(No.2022JC-36)。
文摘A Hybrid Free-Form Deformation(HFFD)method is developed to improve shape preservation in mesh deformation for perforated surfaces,which traditional Free-Form Deformation(FFD)techniques struggle to handle effectively.The proposed method enables high-fidelity parameterized deformation for both flat and curved perforated surfaces while maintaining mesh quality with minimal geometric distortion.To evaluate its effectiveness,comparative studies between HFFD and conventional FFD methods are conducted,demonstrating superior performance in mesh quality and geometric fidelity.The HFFD-based framework is further applied to the Multidisciplinary Design Optimization(MDO)of a double-wall turbine blade leading edge.Results indicate an 11.6%increase in cooling efficiency and a 16.21%reduction in maximum stress.Additionally,compared to traditional geometry-based parameterization in MDO,the HFFD approach improves model processing efficiency by 84.15%and overall optimization efficiency by20.05%.These findings demonstrate HFFD's potential to significantly improve complex engineering design optimization by achieving precise shape preservation and improving computational efficiency.
基金Project supported by the National Natural Science Foundation of China(Nos.124B2043,U2241267,12172155,and 12302278)the Science and Technology Leading Talent Project of Gansu Province of China(No.23ZDKA0009)the Natural Science Foundation of Gansu Province of China(Nos.24JRRA473 and 24JRRA489)。
文摘The contact deformation and buckling of elastic rods against rigid surfaces represent a prevalent phenomenon in applications such as oil drilling,arterial stents,and energy harvesting.This has attracted widespread attention from researchers.In this paper,the deformation and buckling behaviors of a circular arch subject to compression by a rigid plate are investigated with a planar elastic rod model that incorporates tension,shearing,and bending.In comparison with the existing models that solely consider the bending energy,the deflection curve,the internal force distribution,and the critical load of the present model show good agreement with the finite element results.Through the dimensional analysis and order-of-magnitude estimation,we examine the factors influencing the critical load.The study reveals that the semi-central angle of the arch has the most significant effect.The dimensionless geometric parameter describing arch slenderness becomes prominent when the semi-central angle is less than 30°,while Poisson's ratio and the cross-sectional shear correction factor exhibit negligible influence.Furthermore,the variation in the proportions of strain energy components during critical buckling is presented with respect to the semi-central angle and the geometric parameter,thereby delineating the applicable ranges of both the original model(OM)and the modified model(MM).
基金supported in part by the Mining Hydraulic Technology and Equipment Engineering Research Center,Liaoning Technical University,Fuxin,China(Grant No.MHTE23-R04)the Fundamental Research Funds for the Central Universities(ID N25BSS068).
文摘This study presents an implicit multiphysics coupling method integrating Computational Fluid Dynamics(CFD),the Multiphase Particle-in-Cell(MPPIC)model,and the Finite Element Method(FEM),implemented with OpenFOAM,CalculiX,and preCICE to simulate fluid-particle-structure interactions with large deformations.Mesh motion in the fluid field is handled using the radial basis function(RBF)method.The particle phase is modeled by MPPIC,where fluid-particle interaction is described through momentum exchange,and inter-particle collisions are characterized by collision stress.The structural field is solved by nonlinear FEM to capture large deformations induced by geometric nonlinearity.Coupling among fields is realized through a partitioned,parallel,and non-intrusive iterative strategy,ensuring stable transfer and convergence of interface forces and displacements.Notably,the influence of particles on the structure is not direct but mediated by the fluid,while structural motion directly affects particle dynamics.The results demonstrate that the proposed approach effectively captures multiphysics interaction processes and provides a valuable reference for numerical modeling of coupled fluid-particle-structure systems.
文摘Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted drug delivery.For implants,mechanical properties are key performance characteristics,so understanding the deformation and failure mechanisms is essential for selecting the appropriate implant structure.The deformation and fracture processes in PLA samples with different interior architectures have been studied through computer simulation and experimental research.Two TPMS topologies,the Schwarz Diamond and Gyroid architectures,were used for the sample construction by 3D printing.ANSYS software was utilized to simulate compressive deformation.It was found that under the same load,the vonMises stresses in the Gyroid structure are higher than those in the Schwartz Diamond structure,which was associated with the different orientations of the cells in the studied structures in relation to the direction of the loading axis.The deformation process occurs in the local regions of the studied TPMS structures.Maximum von Mises stresses were observed in the vertical parts of the structures oriented along the load direction.It was found that,unlike the Gyroid,the Schwartz Diamond structure contains a frame that forms unique stiffening ribs,which ensures the redistribution of the load under the vertical loading direction.An analysis of the mechanical characteristics of PLA samples with the Schwartz Diamond and Gyroid structures produced by the Fused Deposition Modeling(FDM)method was correlated with computer simulation.The Schwarz Diamond-type structure was shown to have a higher absorption energy than the Gyroid one.A study of the fracture in PLA samples with various cell sizes revealed a particular feature related to the samples’periodic surface topology and the 3D printing process.Scanning electron microscopic(SEM)studies of the samples deformed by compression showed thatwith an increase in the density of the samples,the failure mechanism changes from ductile to quasi-brittle due to the complex participation of both cell deformation and fiber deformation.
基金supported by the China Postdoctoral Science Foundation(CPSF)(Grant No.2024M762769)the Natural Science Basic Research Program of Shaanxi(Grant No.2024JC-YBQN-0333)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20232230).
文摘Slopes are likely to fail in areas with frequent rainfall and earthquakes.The deformation characteristics of unsaturated slopes subjected to post-rainfall earthquakes are investigated using centrifuge model tests and finite element analyses.Three tests of the slope deformation under earthquake and post-rainfall earthquakes are first studied using image analysis techniques.Then,based on an elastoplastic constitutive model,numerical simulations are carried out using the finite element method and compared with the centrifuge test results.Finally,a parametric study is performed to clarify the effects of antecedent rainfall on earthquake-induced slope deformation.The results show that slope deformation caused by post-rainfall earthquakes differs from that caused by earthquakes without antecedent rainfall.The seepage flow and soil strength of the slope are affected by previous rainfall conditions,such as intensity and duration,which directly influence the slope deformation caused by the subsequent earthquake.Soil displacement and strain become greater and the slip surface is more noticeable during the post-rainfall earthquake of higher intensity.In addition,the time interval between the rainfall and the earthquake has a considerable impact on the detailed characteristics of the slope deformation,and the significant deformation occurs at the time of lowest soil strength when seepage flow reaches the lower part of the slope.Moreover,the repeated intermittent rainfall greatly affects the subsequent earthquake-induced slope deformation,the main characteristics of which are closely related to the changes in saturation and strength of the slope.However,with the prolonged time gap between each round of rainfall,the earthquake-induced slope deformation becomes insignificant.
基金financially supported by the National Natural Science Foundation of China(Nos.51909023 and 51775077)the Natural Science Foundation of Liaoning Province(No.2021-MS-140)the Fundamental Research Funds for the Central Universities(No.3132025114)。
文摘Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic deformation in seawater.In this study,we performed a comparative analysis of the UHMWPE dynamics under seawater and water conditions to investigate the plastic deformation of UHMWPE induced by seawater.The results show that the plastic deformation of UHMWPE is amplified in seawater relative to the water conditions.Under thin fluid conditions,frictional interfaces exhibit a higher interfacial friction force and interaction energy in seawater than in water.Compared to freely diffused water molecules,hydrated ions occupy larger interchain spaces within polyethylene.Furthermore,the diffusion of hydrated ions weakens the interchain interactions,promoting more severe polyethylene chain rearrangement and accelerating seawater-induced plastic deformation in UHMWPE during friction.Furthermore,the diffused seawater accelerated the disentangling of the polyethylene chains and enhanced the orderly orientation distribution of polyethylene.Compared to free water molecules,the water molecules of hydrated ions exhibit enhanced attraction to free-flowing water molecules,thereby accelerating seawater flow across submerged UHMWPE surfaces.This flow enhancement promotes surface polyethylene chain mobility in seawater.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea Program(No.RS-2025-02603127,Innovation Research Center for Zero-carbon Fuel Gas Turbine Design,Manufacture,and Safety)。
文摘Understanding the temperature dependent deformation behavior of Mg alloys is crucial for their expanding use in the aerospace sector.This study investigates the deformation mechanisms of hot-rolled AZ61 Mg alloy under uniaxial tension along rolling direction(RD)and transverse direction(TD)at-50,25,50,and 150℃.Results reveal a transition from high strength with limited elongation at-50℃ to significant softening and maximum ductility at 150℃.TD samples consistently showed 2%-6%higher strength than RD;however,this yield anisotropy diminished at 150℃ due to the shift from twinning to thermally activated slip and recovery.Fractography indicated a change from semi-brittle to fully ductile fracture with increasing temperature.Electron backscattered diffraction(EBSD)analysis confirmed twinning-driven grain refinement at low temperatures,while deformation at high temperatures involved grain elongation along shear zones,enabling greater strain accommodation before material failure.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2024ZD1700201)the National Natural Science Foundation of China(Nos.U2034206,51974014 and 51574014)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011631)the National Key Research and Development Project of China(No.2022YFC3004601)。
文摘In-situ stress is a key parameter for underground mine design and rock stability analysis.The borehole overcoring technique is widely used for in-situ stress measurement,but the rheological recovery deformation of rocks after stress relief introduces errors.To improve accuracy,this study proposes an in-situ stress solution theory that incorporates time-dependent stress relief effects.Triaxial stepwise loadingunloading rheological tests on granite and siltstone established quantitative relationships between instantaneous elastic recovery and viscoelastic recovery under different stress levels,confirming their impact on measurement accuracy.By integrating a dual-class elastic deformation recovery model,an improved in-situ stress solution theory was derived.Additionally,accounting for the nonlinear characteristics of rock masses,a determination method for time-dependent nonlinear mechanical parameters was proposed.Based on the CSIRO hollow inclusion strain cell,time-dependent strain correction equations and long-term confining pressure calibration equations were formulated.Finally,the proposed theory was successfully applied at one iron mine(736 m depth)in Xinjiang,China,and one coal mine(510 m depth)in Ningxia,China.Compared to classical theory,the calculated mean stress values showed accuracy improvements of 6.0%and 9.4%,respectively,validating the applicability and reliability of the proposed theory.
基金supported by the National Natural Science Foundation of China(Grant Nos.52069029,52369026)the Belt and Road Special Foundation of National Key Laboratory of Water Disaster Preven-tion(Grant No.2023490411)+2 种基金the Yunnan Agricultural Basic Research Joint Special General Project(Grant Nos.202501BD070001-060,202401BD070001-071)Construction Project of the Yunnan Key Laboratory of Water Security(No.20254916CE340051)the Youth Talent Project of“Xingdian Talent Support Plan”in Yunnan Province(Grant No.XDYC-QNRC-2023-0412).
文摘Deformation prediction for extra-high arch dams is highly important for ensuring their safe operation.To address the challenges of complex monitoring data,the uneven spatial distribution of deformation,and the construction and optimization of a prediction model for deformation prediction,a multipoint ultrahigh arch dam deformation prediction model,namely,the CEEMDAN-KPCA-GSWOA-KELM,which is based on a clustering partition,is pro-posed.First,the monitoring data are preprocessed via variational mode decomposition(VMD)and wavelet denoising(WT),which effectively filters out noise and improves the signal-to-noise ratio of the data,providing high-quality input data for subsequent prediction models.Second,scientific cluster partitioning is performed via the K-means++algorithm to precisely capture the spatial distribution characteristics of extra-high arch dams and ensure the consistency of deformation trends at measurement points within each partition.Finally,CEEMDAN is used to separate monitoring data,predict and analyze each component,combine the KPCA(Kernel Principal Component Analysis)and the KELM(Kernel Extreme Learning Machine)optimized by the GSWOA(Global Search Whale Optimization Algorithm),integrate the predictions of each component via reconstruction methods,and precisely predict the overall trend of ultrahigh arch dam deformation.An extra high arch dam project is taken as an example and validated via a comparative analysis of multiple models.The results show that the multipoint deformation prediction model in this paper can combine data from different measurement points,achieve a comprehensive,precise prediction of the deformation situation of extra high arch dams,and provide strong technical support for safe operation.
基金financial support from NSF ExpandQISE program.The synthesis of tellurene was supported by NSF under grant no.CMMI-2046936supports from Purdue Research Foundation.
文摘Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study elucidates the fundamental mechanisms of ultrafast laser shock imprinting(LSI)in two-dimensional tellurium(Te),establishing a direct relationship between strain field orientation,mold topology,and anisotropic structural evolution.This is the first demonstration of ultrafast LSI on chiral chain Te unveiling orientation-sensitive dislocation networks.By applying controlled strain fields parallel or transverse to Te’s helical chains,we uncover two distinct deformation regimes.Strain aligned parallel to the chain’s direction induces gliding and rotation governed by weak interchain interactions,preserving covalent intrachain bonds and vibrational modes.In contrast,transverse strain drives shear-mediated multimodal deformations—tensile stretching,compression,and bending—resulting in significant lattice distortions and electronic property modulation.We discovered the critical role of mold topology on deformation:sharp-edged gratings generate localized shear forces surpassing those from homogeneous strain fields via smooth CD molds,triggering dislocation tangle formation,lattice reorientation,and inhomogeneous plastic deformation.Asymmetrical strain configurations enable localized structural transformations while retaining single-crystal integrity in adjacent regions—a balance essential for functional device integration.These insights position LSI as a precision tool for nanoscale strain engineering,capable of sculpting 2D material morphologies without compromising crystallinity.By bridging ultrafast mechanics with chiral chain material science,this work advances the design of strain-tunable devices for next-generation electronics and optoelectronics,while establishing a universal framework for manipulating anisotropic 2D systems under extreme strain rates.This work discovered crystallographic orientation-dependent deformation mechanisms in 2D Te,linking parallel strain to chain gliding and transverse strain to shear-driven multimodal distortion.It demonstrates mold geometry as a critical lever for strain localization and dislocation dynamics,with sharp-edged gratings enabling unprecedented control over lattice reorientation.Crucially,the identification of strain field conditions that reconcile severe plastic deformation with single-crystal retention offers a pathway to functional nanostructure fabrication,redefining LSI’s potential in ultrafast strain engineering of chiral chain materials.
