The rapid advancement of wearable electronic devices has paved the way for a more intelligent and interconnected world.However,ensuring the sustainable energy supply for these devices remains a critical challenge,part...The rapid advancement of wearable electronic devices has paved the way for a more intelligent and interconnected world.However,ensuring the sustainable energy supply for these devices remains a critical challenge,particularly for specialized populations and professionals in demanding environments,where a lack of power can pose life-threatening risks.Herein,we propose a mechanically intelligent biomechanical energy harvesting approach that adapts to complex human motion excitations,thereby improving the energy harvesting performance.Leveraging a mechanical intelligence mechanism,the energy harvester aligns with human physiological habits,selectively activating or deactivating as needed.The system can also adapt to excitations of varying directions,amplitudes,and frequencies.Furthermore,the string tension helps reduce the impact forces on the knee joint during foot strikes.A theoretical model for the biomechanical energy harvesting system is developed to describe its dynamic and electrical characteristics,and a prototype is fabricated and tested under diverse conditions.The experimental results are in good agreement with the simulation trends,validating the effectiveness of the theoretical model.A test subject running at 8 km/h for 90 seconds can successfully power a smartphone for 20 seconds,demonstrating the viability of self-powered applications.This mechanically intelligent biomechanical energy harvesting method holds a promising solution for the sustainable power supply for wearable electronic devices.展开更多
Osteoarthritis(OA),the most common chronic joint disease,leads to remarkable morbidity and disability.The development of preclinical models that accurately recapitulate the bio-chemo-mechanical microenvironment of ost...Osteoarthritis(OA),the most common chronic joint disease,leads to remarkable morbidity and disability.The development of preclinical models that accurately recapitulate the bio-chemo-mechanical microenvironment of osteoarthritic joints is crucial for elucidating OA pathogenesis and facilitating drug development.In this study,we present a microfluidics-based cartilage-on-a-chip model that integrates tunable mechanical stimulation and inter-tissue/cell communication,mimicking the key physiological characteristics of articular cartilage for organ-level OA research.By applying controllable mechanical compression,we established a model that captures healthy and injury hallmarks of the cartilage and directly observed the mechanotransduction responses in chondrocytes.We further demonstrated that mechanically damaged cartilage induces synovial abnormalities and immune dysregulation and explored the potential of our chip as a platform for screening therapeutic targets.This cartilage-on-a-chip offers an in vitro system with a close-to-in vivo microenvironment for investigating complex bio-chemo-mechanical interactions,paving the way for advanced studies on OA pathogenesis and drug screening.展开更多
Two-dimensional(2D)materials have attracted extensive attention from aerospace,integrated circuits,precision sensors,and flexible electronics due to their unique layered structure and excellent physicochemical propert...Two-dimensional(2D)materials have attracted extensive attention from aerospace,integrated circuits,precision sensors,and flexible electronics due to their unique layered structure and excellent physicochemical properties.In practice applications,the components of functional nanodevices are subjected to mechanical stress,which can affect the robust performance and structural reliability of these devices.Therefore,it is imperative to explore the mechanical properties and underlying mechanisms of 2D materials.However,researchers have an inadequate understanding of the accuracy of various in situ microscopy techniques and neglect the significance of high-quality,clean transfer techniques,resulting in deviated measurement results.There is now an urgent need to develop guidelines that allow researchers to select appropriate material transfer techniques and mechanical testing strategies based on the specific properties of 2D materials.Furthermore,the mechanical mechanism of 2D materials lacks systematic and comprehensive studies,which hinders researchers from deeply understanding the relationship between the material structure and the device performance.This work reviews the latest progress in the mechanics of 2D materials,focusing on the challenges of various transfer techniques and in situ microscopy techniques in mechanical testing,and provides effective guidance for the formulation of experimental schemes for mechanical testing.In addition,we offer detailed mechanistic insights into the fracture behavior,geometric dimension effects,edge defects,and interlayer bonding effects of 2D materials.This work is expected to advance the field development of 2D material mechanics.展开更多
The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solutio...The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.展开更多
Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled t...Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.展开更多
Ion-exchange Polymer-Metal Composites(IPMCs)gain huge attentions due to large deformation,rapid electromechanical response,and high energy conversion efficiency.Deflection of IPMC arises from the volumetric swelling e...Ion-exchange Polymer-Metal Composites(IPMCs)gain huge attentions due to large deformation,rapid electromechanical response,and high energy conversion efficiency.Deflection of IPMC arises from the volumetric swelling effect induced by the concentration gradient of hydrated cations between the two electrodes,thus the volume of hydrated cation deter-mines the motion magnitude and direction of IPMC.H ion is one of the most commonly used driving cations for IPMC.However,due to its unique characteristics,particularly the inability to accurately quantify its hydration volume,existing literatures primarily focus on the physical driving models for metallic cations,i.e.,Na+,no driving model for the H ion is reported until now.This paper proposes a novel model of H ion escape from the water's body-centered cubic lattice to count the hydration volume.Number(n)of water molecules carried by the H ion is solved by combining the Lennard-Jones potential energy function with Maxwell's velocity distribution.The specific n value is equivalent to 4.04 for the H ion inside Nafion electrolyte under a 3.0 V DC electric field.Substituting it into the classic Friction Model(proposed by Tadokoro et al.at 2000),actuation behaviors of H ion driven IPMC were therefore achieved through Matlab calculations and Abaqus simulations.The calculated results of dynamic displacement and force highly match to the experimental data form the Nafion IPMC actuator driven by same electric field,showing a highly reliability of the established escape model.展开更多
The paper presents the results of geomechanical and CT-based studies of deformation,fracture and filtration processes in reservoir rocks of the Arctic shelf gas condensate field.The experimental study combines(i)deter...The paper presents the results of geomechanical and CT-based studies of deformation,fracture and filtration processes in reservoir rocks of the Arctic shelf gas condensate field.The experimental study combines(i)determination of mechanical properties,(ii)true triaxial physical modeling of near-wellbore filtration and geomechanical processes,(iii)triaxial sand production studies,and(iv)digital CT-analysis of the rock matrix and sand particles.Based on true triaxial physical modeling,the relationships between permeability,rock deformation,and stresses around a horizontal well during drawdown were determined.Hollow cylinder-type tests were used to determine the stress conditions for sand release initiation,the intensity of sand production under varying stress states,and the total volume of sand produced.Digital particle size analysis of the matrix and released sand provided insights into the dominant mechanisms of hole failure during sand production.A significant strength anisotropy of reservoir rocks was identified,suggesting that drawdown in horizontal wells could lead to asymmetric bottomhole zone fracture,initiated at the upper and lower points on the wellbore contour.The obtained results allowed to determine(i)the drawdowns required to maintain wellbore stability in the given reservoir interval;(ii)the optimal parameters of downhole gravel filter screens for sand control;(iii)to identify the prevailing type of wellbore fracture and to localize failure initiation points on the wellbore walls.The results highlight the importance of integrating modern laboratory core analysis methods to enhance the development of complex reservoirs and reduce the risks of fractures and sand production in weakly cemented formations.展开更多
5xxx Al alloys are widely used in additive manufacturing(AM)components across various industries due to their advantageous properties,including low density,high strength,and excellent corrosion resistance.However,conv...5xxx Al alloys are widely used in additive manufacturing(AM)components across various industries due to their advantageous properties,including low density,high strength,and excellent corrosion resistance.However,conventional melt-based AM methods often introduce defects such as pores,cracks and elemental evaporation.In the present study,a novel screw extrusion-plasticizing friction stir deposition(SEFSD)process,which enables the extrusion plasticization of 5183 particulate feedstocks via a three-stage tapered screw tool,was utilized to fabricate a 20-layer 5183 deposition wall through continuous linear reciprocating deposition in the solid state.The deposition wall exhibited a refined equiaxed microstructure.Due to the low stacking fault energy(SFE)of Al-Mg alloy,the influence of thermal cycles on microstructural evolution was minimal.Overall,the deposition wall demonstrated excellent mechanical properties,though strength and ductility in the deposition direction were reduced due to interlayer defects,which could be mitigated by incorporating stir pins or enhancing interlayer adhesive friction to intensify the material flow.This study confirms the applicability and significant potential of SEFSD for additive manufacturing 5xxx Al alloy components.展开更多
Cold deformation treatment of Cu-bearing stainless steel through a cold rolling process combined with electric pulse treatment(EPT)can significantly improve the microstructure and formability of cold-rolled Cu-bearing...Cold deformation treatment of Cu-bearing stainless steel through a cold rolling process combined with electric pulse treatment(EPT)can significantly improve the microstructure and formability of cold-rolled Cu-bearing stainless steel.The microstructure after EPT was characterized by scanning electron microscopy,transmission electron microscopy,and in-situ tensile testing.It is found that compared with conventional heat treatment,EPT process can significantly promote the nucleation rate and mobility at grain boundaries of the deformed samples,greatly accelerating the recovery and static recrystallization of Cu-bearing stainless steel samples at lower temperatures and contributing to the recovery of anisotropy and the re-molding of deformed samples.Microstructural characterization and theoretical analyses show that the rapid recrystallization during EPT process is caused not only by Joule heating effects but also by non-thermal effects that accelerate grain boundary migration and dislocation destruction and regeneration.In addition,EPT process significantly accelerated the nucleation and precipitation growth of Cu-rich phase.The coarsening of Cu-rich phase during EPT process is due to not only the high vacancy diffusion coefficient under the action of the electric pulse but also the increase in the vacancy diffusion flux induced by the electromigration in the process of the electric pulse.展开更多
(NbZrHfTi)C high-entropy ceramics,as an emerging class of ultra-high-temperature materials,have garnered significant interest due to their unique multi-principal-element crystal structure and exceptional hightemperatu...(NbZrHfTi)C high-entropy ceramics,as an emerging class of ultra-high-temperature materials,have garnered significant interest due to their unique multi-principal-element crystal structure and exceptional hightemperature properties.This study systematically investigates the mechanical properties of(NbZrHfTi)C high-entropy ceramics by employing first-principles density functional theory,combined with the Debye-Grüneisen model,to explore the variations in their thermophysical properties with temperature(0–2000 K)and pressure(0–30 GPa).Thermodynamically,the calculated mixing enthalpy and Gibbs free energy confirm the feasibility of forming a stable single-phase solid solution in(NbZrHfTi)C.The calculated results of the elastic stiffness constant indicate that the material meets the mechanical stability criteria of the cubic crystal system,further confirming the structural stability.Through evaluation of key mechanical parameters—bulk modulus,shear modulus,Young’s modulus,and Poisson’s ratio—we provide comprehensive insight into the macro-mechanical behaviour of the material and its correlation with the underlying microstructure.Notably,compared to traditional binary carbides and their average properties,(NbZrHfTi)C exhibits higher Vickers hardness(Approximately 28.5 GPa)and fracture toughness(Approximately 3.4 MPa⋅m^(1/2)),which can be primarily attributed to the lattice distortion and solid-solution strengthening mechanism.The study also utilizes the quasi-harmonic approximation method to predict the material’s thermophysical properties,including Debye temperature(initial value around 563 K),thermal expansion coefficient(approximately 8.9×10^(−6) K−1 at 2000 K),and other key parameters such as heat capacity at constant volume.The results show that within the studied pressure and temperature ranges,(NbZrHfTi)C consistently maintains a stable phase structure and good thermomechanical properties.The thermal expansion coefficient increasing with temperature,while heat capacity approaches the Dulong-Petit limit at elevated temperatures.These findings underscore the potential of(NbZrHfTi)C applications in ultra-high temperature thermal protection systems,cutting tool coatings,and nuclear structural materials.展开更多
This study presents a framework involving statistical modeling and machine learning to accurately predict and optimize the mechanical and damping properties of hybrid granite-epoxy(G-E)composites reinforced with cast ...This study presents a framework involving statistical modeling and machine learning to accurately predict and optimize the mechanical and damping properties of hybrid granite-epoxy(G-E)composites reinforced with cast iron(CI)filler particles.Hybrid G-E composite with added cast iron(CI)filler particles enhances stiffness,strength,and vibration damping,offering enhanced performance for vibration-sensitive engineering applications.Unlike conventional approaches,this work simultaneously employs Artificial Neural Networks(ANN)for highaccuracy property prediction and Response Surface Methodology(RSM)for in-depth analysis of factor interactions and optimization.A total of 24 experimental test data sets of varying input factors(granite weight%,epoxy weight%,and CI filler weight%)were utilized to train and test the prediction models using an ANN approach and further analyze the interaction effects using RSM.Mechanical properties,including tensile,compressive,and flexural strength,elastic modulus,density and damping properties measured under various testing conditions,were set as output parameters for prediction.This study analyzed and optimized the performance of the ANN model using Bayesian Regularization and Levenberg-Marquardt algorithms to identify the best performing number of neurons in the hidden layer for achieving the highest prediction accuracy.The proposed ANN framework achieved an exceptional average determination coefficient(R2)exceeding 99%,with Bayesian Regularization demonstrating remarkable stability in the 22-neuron range and minimal variation across all properties.RSM and ANN form a powerful framework for predicting and optimizing hybrid G-E composite properties,enabling efficient design for vibration-critical applications with reduced experimental effort and performance optimization.展开更多
To comprehensively explore the impact of binder content on the mechanical properties of the Polymer bonded explosive(PBX)substitute material(Polymer-bonded Analogue Explosive(PAE)—it is renowned for its outstanding h...To comprehensively explore the impact of binder content on the mechanical properties of the Polymer bonded explosive(PBX)substitute material(Polymer-bonded Analogue Explosive(PAE)—it is renowned for its outstanding high-temperature resistance,exceptional mechanical properties,excellent chemical stability,and superior electrical insulation),a series of experiments are meticulously carried out.The dynamic and static mechanical properties,along with the microstructure of PAE,are precisely measured through the Split Hopkinson Pressure Bar(SHPB)test,static compression tests,and Scanning Electron Microscopy(SEM).The dynamic performance test outcomes clearly indicate that both the binder content(2%,4%,6%)and temperature(25℃,45℃,70℃)exert a substantial influence on the dynamic mechanical properties of PAE.Specifically,as the binder content increases,the elasticmodulus increases,demonstrating higher stiffness,and the longer failure duration represents a prolonged fracture process rather than an improved deformation strain to failure.This means the strength-related stiffness rises with binder content,but the overall ductility does not increase.Notably,PAE with 2%the Ethylene-Vinyl Acetate Copolymer(EVA)—it bonds well with a variety ofmaterials,such asmetal,wood,and plastic—exhibits distinct plastic deformation behavior,while PAE samples with 4%and 6%EVA display evident brittle fracture characteristics.Additionally,the mechanical properties of PAE are highly sensitive to temperature variations.Among the tested temperatures,PAE showcases the most favorable performance at 45℃.The static performance test results reveal that an increment in binder content effectively helps to reduce the temperature sensitivity of temperature(-40℃,25℃,50℃,70℃)on PAE and enhance its static mechanical properties.The maximum compressive strength gradually diminishes as the temperature rises.However,it should be noted that an excessively high binder content will undermine the mechanical properties of PAE.With the increase in binder content,the compressive modulus demonstrates relatively stable changes under both lowtemperature and high-temperature conditions.The SEM analysis results demonstrate that,aside fromthe initial defects inherent in the material preparation process,the components of PAE are firmly combined.Throughout the tests,no new pores or microcracks emerge,which strongly indicates that the mechanical properties of PAE remain stable.展开更多
The high hydrophilicity of pineapple leaf fibres(PALF)limits their use in cement-and gypsum-based composites exposed to moisture.This study evaluates,for the first time,the combined effect of palm kernel oil and beesw...The high hydrophilicity of pineapple leaf fibres(PALF)limits their use in cement-and gypsum-based composites exposed to moisture.This study evaluates,for the first time,the combined effect of palm kernel oil and beeswax on the hygroscopic resistance and mechanical stability of PALF.The fibres were functionalised with three formulations(oil,wax,and a 1:2 oil/wax blend)applied at different mass ratios(CR=0.5-2).Treatments increased the average bundle diameter by up to+46%(238μm)and reduced density down to 1.06 g/cm^(3).Hygroscopically,water absorption decreased from 202.4%(raw fibres)to 76.3%(CR=2),representing a maximum reduction of 59.4%in saline medium,while moisture regain dropped from 27.9%to 14.6%(−47.7%).The oil/wax blend proved most effective,simultaneously reducing water absorption(−51.2%)and moisture regain(−46.8%)at CR=1.Mechanically,the fibres retained tensile strength(415.2 vs.460.8 MPa,+11%at CR=1)and exhibited enhanced ductility(+62.5%,with elongation at break increasing from 1.6%to 2.6%),without significantly altering Young’s modulus(12.3 to 10 GPa).Water absorption kinetics were accurately described by the Czel and Mohsenin models(R^(2)>0.98).These findings clearly demonstrate that bio-based lipid coatings can provide an eco-friendly alternative to conventional chemical treatments.They improve hygroscopic resistance and preserve mechanical integrity of PALF,providing original quantitative data for their integration into durable cement-and gypsum-based composites subjected to humid or cyclic wet-dry conditions.展开更多
Deep rock engineering is affected by coupled thermo-hydro-mechanical(THM)-dynamic fields,necessitating the elucidation of the dynamic mechanical behavior and failure mechanisms.This study utilized a Multi-field Couple...Deep rock engineering is affected by coupled thermo-hydro-mechanical(THM)-dynamic fields,necessitating the elucidation of the dynamic mechanical behavior and failure mechanisms.This study utilized a Multi-field Coupled Controlled Split Hopkinson Pressure Bar(MCC-SHPB)system to elucidate the cross-scale dynamic responses of rocks and the boundaries of failure modes under THM coupling.Impact tests were conducted on green sandstone under coupled conditions of temperature(25℃-80℃),confining pressure(0-15 MPa),and seepage water pressure(0-15 MPa).Scanning electron microscopy(SEM)microstructural characterization and COMSOL Multiphysics numerical simulations were conducted,and a dynamic constitutive theoretical framework and failure-prediction methodology were established.We investigated the impact toughness index(I_(t)),dynamic modulus(E_(d)),dynamic triaxial compressive strength(TCS_(d)),fragmentation degree(W),and failure modes of green sandstone under thermo-confining pressure-seepage-impact loading conditions.The key findings reveal that the(I_(t))reflects different energy regulation mechanisms across different confining pressure regimes.Thermal-microcrack interactions dominate at low pressure,and energy absorption prevails at high pressure.A triphasic dynamic modulus model captures stiffness evolution under energy-driven conditions,revealing cross-scale crack nucleation-propagation and fragment reorganization.The TCSd inflection point signifies energy dissipation shifts,causing nonlinear skeleton bearing-capacity degradation.A critical criterion based on the W was established to distinguish between the two failure modes and predict the unstable failure initiation.Numerical simulations were used to elucidate the effects of inertia-dominated crack propagation and stress wave interference,validating the critical criterion and the predictive accuracy of the theoretical model during cross-scale failure.This study provides a theoretical foundation for assessing the dynamic stability of rock masses subjected to multi-field coupling during deep resource exploitation.展开更多
The influence of oscillation amplitude on molten pool thermal history,weld morphology characteristics,microstructural evolution,and mechanical properties during laser oscillating welding of QP980 steel was systematica...The influence of oscillation amplitude on molten pool thermal history,weld morphology characteristics,microstructural evolution,and mechanical properties during laser oscillating welding of QP980 steel was systematically investigated.Results show that laser beam oscillation significantly regulates molten pool thermomechanical behavior through optimized spatial energy distribution,thereby enabling microstructural reconstruction and joint performance enhancement.As the oscillation amplitude increases from 0 to 0.8 mm,the molten pool duration extends to 1.7 times the original value,while peak temperature and average cooling rate decrease by 19%and 39%,respectively.This thermal regulation promotes weld surface width expansion from 0.72 to 1.07 mm.The welding mode undergoes a progressive transition from keyhole mode→transitional mode→conduction mode.This transformation effectively suppresses porosity defects,substantially reducing porosity from 1.8%to 0.15%.Microstructural analysis indicates that oscillation modifies the maximum temperature gradient direction within the molten pool,facilitating preferential growth of coarse columnar grains along the welding centerline to establish load-transfer-favorable crystallographic orientations.The synergistic effects of these factors substantially improve joint mechanical properties:lap joint shear load increases by 81.5%(7.6→13.8 kN),and fracture elongation is enhanced by 135%(0.98→2.3 mm).The operational principles of laser oscillation parameters on the welding quality of QP980 steel were elucidated,providing theoretical foundations for joining process optimization.展开更多
To investigate the complex relationship between rolling process parameters and mechanical properties of AZ31 magnesium alloy rolled sheets,the Leave-One-Out Cross-Validation(LOOCV)and parameter tuning were applied to ...To investigate the complex relationship between rolling process parameters and mechanical properties of AZ31 magnesium alloy rolled sheets,the Leave-One-Out Cross-Validation(LOOCV)and parameter tuning were applied to optimizing hyper-parameters for the four(BPNN,SVR,RF,and KNN)machine learning models.An interpretable prediction model based on machine learning and SHapley Additive exPlanations(SHAP),as well as an analytical method combining the SHAP model and the Pearson Correlation Coefficient(PCC),were proposed.The results showed that among the four models,the SVR model was able to simultaneously and accurately predict the ultimate tensile strength(UTS)and elongation(EL).According to the combination analysis of PCC and the magnesium alloy rolling forming mechanism,it was found that strain rate and reduction displayed a negative and positive correlation with UTS,respectively,while rolling temperature and reduction illustrated a positive and negative correlation with EL,respectively.Through the SHAP method,which could interpret the output results of the SVR machine learning model,it was deduced that reduction and strain rate played an important role in the SVR model of the outputs of the UTS and EL,respectively.Combining SHAP with PCC,it was found that strain rate and reduction had a greater influence on the UTS than rolling temperature,whereas strain rate and rolling temperature had more influence on the EL compared to reduction.展开更多
A parametric study was performed to explore the effect of runner thickness,filtration,and hydrogen content on the mechanical properties and defect formation in Al-7%Si-0.3%Mg(2L99)sand castings.A two-level full factor...A parametric study was performed to explore the effect of runner thickness,filtration,and hydrogen content on the mechanical properties and defect formation in Al-7%Si-0.3%Mg(2L99)sand castings.A two-level full factorial design of experiments was used to statistically evaluate these parameters and the tensile properties were characterized via Weibull distribution analysis.The findings reveal that decreasing the runner thickness from25 mm to 10 mm and using 10 PPI ceramic filters improve mechanical properties by minimizing double oxide film entrainment as confirmed by electron microscopy examination.In addition,lowering hydrogen concentrations within the Al alloy from 0.24 cm^(3)/100 g Al to 0.12 cm^(3)/100 g Al is also shown to enhance casting integrity by suppressing bifilm inflation and subsequent pore formation.ANOVA results indicate that the hydrogen content is the most important factor,contributing 53%to the variability in mechanical properties,followed by filtration(25%)and runner thickness(17%).The optimized casting conditions including thin runners(10 mm thick),melt filtration,and a low hydrogen level(0.12 cm^(3)/100 g Al),result in an approximately 474%increase in the shape factor and a 107%increase in the characteristic life of UTS,as well as an approximately 413%increase in the shape factor and a 149%increase in characteristic life of elongation.The outcomes suggest that controlled filling systems and melt treatment are critical for producing consistent,high integrity aluminum castings in industrial applications.展开更多
Biodegradable metals(BMs)have shown significant potential for applications in the field of orthopedic implants.These materials gradually degrade after implantation,eventually disappear without residue,provide necessar...Biodegradable metals(BMs)have shown significant potential for applications in the field of orthopedic implants.These materials gradually degrade after implantation,eventually disappear without residue,provide necessary mechanical support during degradation,and closely integrate with bone tissues.Fe-based BMs are particularly notable for their good mechanical properties and biocompatibility.However,their slow degradation rate is a limitation.The emergence of Mn-incorporated Fe-based alloys(Fe-Mn alloys)offers the possibilities for addressing issues of slow degradation rate and incompatibility of magnetic resonance imaging(MRI)for Fe alloys.This review summarizes the advantages of Fe-Mn alloys as orthopedic implants,and the cutting-edge advances in degradation,mechanical and magnetic properties,and osteogenic performance.The cytotoxicity issue is addressed for the porous structured Fe-Mn alloys caused by the enrichment of manganese ions,and thus the main challenge and the development are involved for the Fe-Mn alloys to achieve a balance among biocompatibility,structure,and degradation rate.Also the perspectives are proposed for Fe-Mn alloys as orthopedic implants.展开更多
Snap-through instability-based mechanical metamaterials(SIMMs)with bistability,multistability,negative stiffness,or excellent energy absorption and dissipation performance play an important role in various advanced fu...Snap-through instability-based mechanical metamaterials(SIMMs)with bistability,multistability,negative stiffness,or excellent energy absorption and dissipation performance play an important role in various advanced functional applications.They can serve as energy absorbers,energy dampers,or mechanical memory and logic computing devices,while also providing amplified force output and faster response time in flexible robots,or implementing sensing functions combined with piezoelectric or triboelectric electricity.However,thus far,research on SIMMs that have non-fixed boundary constraints,proactive responsiveness,multi-physical field cross-coupling,and deep information processing capabilities is still facing significant challenges,potentially hindering the development and cross-field comprehensive applications of truly intelligent SIMMs.Our objective is to furnish a concise categorization of SIMMs and offer direction for innovative design and functional implementations.We have emphasized that the non-fixed boundary constraint will expand the design possibilities,while the use of stimulus-responsive materials and 4D printing technology will create novel opportunities for the design of SIMMs.These advancements are expected to achieve innovative mechanical properties and functions.展开更多
High geo-stress and high temperature in deep rock engineering increase the possibility of engineering and geological disasters in discontinuous rocks.However,the influence of thermomechanical coupling on the shear beh...High geo-stress and high temperature in deep rock engineering increase the possibility of engineering and geological disasters in discontinuous rocks.However,the influence of thermomechanical coupling on the shear behavior and damage evolution of prefractured granite remains immature.In this context,true triaxial laboratory tests and discrete element method simulations under different confining pressures(σ3=3 MPa,σ2=4 MPa,andσ3=80 MPa,σ2=100 MPa)and temperatures(25℃-500℃)were carried out on rough granite fractures with two different orientations.Results indicate that high temperature and high confining pressure increase the peak strength of the prefractured specimen,leading to more microcracks in the host rock and more gouges between the surfaces.Thermal strengthening at low temperatures(<300℃)and residual stick-slip only occur under a greater confining pressure for prefractured specimens.High confining pressure suppresses generation of the thermal microcracks in the heating stage.Cracks first initiate in the asperities on the fracture surfaces,and then propagate into the rock matrix during the mechanical loading stage.In addition,prefractured granite with a larger fracture angle is characterized by smaller peak and residual strength,faster residual slip,fewer new cracks on the specimen surface,and a more pronounced thermal strengthening effect on peak strength.The slip tendency analysis indicates that a higher maximum principal stress(s1)and a large fracture angle(45°-75°)generally result in a higher potential for fracture slip or activation.This study will contribute to a better understanding of the fracture shear mechanism under true triaxial thermomechanical coupling conditions and provides new insights into the stability evaluation of deep dynamic geological hazards.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.12202262,12172127,12032015,and 12121002)the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(No.2023QNRC001)the Hunan Province Science and Technology Innovation Program of China(Nos.2025JJ20012 and 2025RC4022)。
文摘The rapid advancement of wearable electronic devices has paved the way for a more intelligent and interconnected world.However,ensuring the sustainable energy supply for these devices remains a critical challenge,particularly for specialized populations and professionals in demanding environments,where a lack of power can pose life-threatening risks.Herein,we propose a mechanically intelligent biomechanical energy harvesting approach that adapts to complex human motion excitations,thereby improving the energy harvesting performance.Leveraging a mechanical intelligence mechanism,the energy harvester aligns with human physiological habits,selectively activating or deactivating as needed.The system can also adapt to excitations of varying directions,amplitudes,and frequencies.Furthermore,the string tension helps reduce the impact forces on the knee joint during foot strikes.A theoretical model for the biomechanical energy harvesting system is developed to describe its dynamic and electrical characteristics,and a prototype is fabricated and tested under diverse conditions.The experimental results are in good agreement with the simulation trends,validating the effectiveness of the theoretical model.A test subject running at 8 km/h for 90 seconds can successfully power a smartphone for 20 seconds,demonstrating the viability of self-powered applications.This mechanically intelligent biomechanical energy harvesting method holds a promising solution for the sustainable power supply for wearable electronic devices.
基金supported by the National Natural Science Foundation of China(Nos.12072010 and 11674019)the Fundamental Research Funds for the Central Universities(No.YWF22-K-101)the National Key Research and Development Program of China(No.2022YFB3804300).
文摘Osteoarthritis(OA),the most common chronic joint disease,leads to remarkable morbidity and disability.The development of preclinical models that accurately recapitulate the bio-chemo-mechanical microenvironment of osteoarthritic joints is crucial for elucidating OA pathogenesis and facilitating drug development.In this study,we present a microfluidics-based cartilage-on-a-chip model that integrates tunable mechanical stimulation and inter-tissue/cell communication,mimicking the key physiological characteristics of articular cartilage for organ-level OA research.By applying controllable mechanical compression,we established a model that captures healthy and injury hallmarks of the cartilage and directly observed the mechanotransduction responses in chondrocytes.We further demonstrated that mechanically damaged cartilage induces synovial abnormalities and immune dysregulation and explored the potential of our chip as a platform for screening therapeutic targets.This cartilage-on-a-chip offers an in vitro system with a close-to-in vivo microenvironment for investigating complex bio-chemo-mechanical interactions,paving the way for advanced studies on OA pathogenesis and drug screening.
基金National Natural Science Foundation of China(Grant.Nos.52422505,12274124)the Shanghai Pilot Program for Basic Research(Grant.No.22TQ14001006)+2 种基金National Natural Science Foundation of China(Grant No.52275149)the Scientific Research Innovation Capability Support Project for Young Faculty(Grant No.ZYGXQNJSKYCXNLZCXM-D5)Innovative Research Group Project of the National Natural Science Foundation of China(Grant.No.52321002)。
文摘Two-dimensional(2D)materials have attracted extensive attention from aerospace,integrated circuits,precision sensors,and flexible electronics due to their unique layered structure and excellent physicochemical properties.In practice applications,the components of functional nanodevices are subjected to mechanical stress,which can affect the robust performance and structural reliability of these devices.Therefore,it is imperative to explore the mechanical properties and underlying mechanisms of 2D materials.However,researchers have an inadequate understanding of the accuracy of various in situ microscopy techniques and neglect the significance of high-quality,clean transfer techniques,resulting in deviated measurement results.There is now an urgent need to develop guidelines that allow researchers to select appropriate material transfer techniques and mechanical testing strategies based on the specific properties of 2D materials.Furthermore,the mechanical mechanism of 2D materials lacks systematic and comprehensive studies,which hinders researchers from deeply understanding the relationship between the material structure and the device performance.This work reviews the latest progress in the mechanics of 2D materials,focusing on the challenges of various transfer techniques and in situ microscopy techniques in mechanical testing,and provides effective guidance for the formulation of experimental schemes for mechanical testing.In addition,we offer detailed mechanistic insights into the fracture behavior,geometric dimension effects,edge defects,and interlayer bonding effects of 2D materials.This work is expected to advance the field development of 2D material mechanics.
基金Tianjin Municipal Natural Science Foundation(23JCYBJC00040)National Natural Science Foundation of China(52175369)。
文摘The TiB+TiC dual-reinforced B_(4)C/TC4 composite was in-situ fabricated via incorporating 0.5wt%B_(4)C reinforcement during the laser melting deposition process.Different heat treatments of annealing and solid solution were used to regulate the microstructure,mechanical properties,and corrosion properties of B_(4)C/TC4 composite.Results show that with the increase in temperature from 500℃to 800°C,partial lamellarα-Ti in the as-deposited sample is gradually transformed into equiaxedα-Ti,accompanied by the disappearance of basketweave microstructure.At 1100°C,a small portion of TiC phase suffers fusion.This composite exhibits the optimal combination of strength and plasticity after annealing at 500℃for 4 h followed by furnace cooling,which is attributed to the stress release effect and the refined basketweave microstructure.However,this composite shows a decline in corrosion resistance after various heat treatments due to grain coarsening and micro-galvanic corrosion.
基金supported by the Research Project on Strengthening the Construction of an Important Ecological Security Barrier in Northern China by Higher Education Institutions in the Inner Mongolia Autonomous Region(STAQZX202313)the Inner Mongolia Autonomous Region Education Science‘14th Five-Year Plan’2024 Annual Research Project(NGJGH2024635).
文摘Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.
基金National Natural Science Foundations of China(52275295)Central Plains Science and Technology Innovation Leading Talents(234200510026).
文摘Ion-exchange Polymer-Metal Composites(IPMCs)gain huge attentions due to large deformation,rapid electromechanical response,and high energy conversion efficiency.Deflection of IPMC arises from the volumetric swelling effect induced by the concentration gradient of hydrated cations between the two electrodes,thus the volume of hydrated cation deter-mines the motion magnitude and direction of IPMC.H ion is one of the most commonly used driving cations for IPMC.However,due to its unique characteristics,particularly the inability to accurately quantify its hydration volume,existing literatures primarily focus on the physical driving models for metallic cations,i.e.,Na+,no driving model for the H ion is reported until now.This paper proposes a novel model of H ion escape from the water's body-centered cubic lattice to count the hydration volume.Number(n)of water molecules carried by the H ion is solved by combining the Lennard-Jones potential energy function with Maxwell's velocity distribution.The specific n value is equivalent to 4.04 for the H ion inside Nafion electrolyte under a 3.0 V DC electric field.Substituting it into the classic Friction Model(proposed by Tadokoro et al.at 2000),actuation behaviors of H ion driven IPMC were therefore achieved through Matlab calculations and Abaqus simulations.The calculated results of dynamic displacement and force highly match to the experimental data form the Nafion IPMC actuator driven by same electric field,showing a highly reliability of the established escape model.
基金supported by the Russian Science Foundation(Grant No.23-77-01037,https://rscf.ru/en/project/23-77-01037/).
文摘The paper presents the results of geomechanical and CT-based studies of deformation,fracture and filtration processes in reservoir rocks of the Arctic shelf gas condensate field.The experimental study combines(i)determination of mechanical properties,(ii)true triaxial physical modeling of near-wellbore filtration and geomechanical processes,(iii)triaxial sand production studies,and(iv)digital CT-analysis of the rock matrix and sand particles.Based on true triaxial physical modeling,the relationships between permeability,rock deformation,and stresses around a horizontal well during drawdown were determined.Hollow cylinder-type tests were used to determine the stress conditions for sand release initiation,the intensity of sand production under varying stress states,and the total volume of sand produced.Digital particle size analysis of the matrix and released sand provided insights into the dominant mechanisms of hole failure during sand production.A significant strength anisotropy of reservoir rocks was identified,suggesting that drawdown in horizontal wells could lead to asymmetric bottomhole zone fracture,initiated at the upper and lower points on the wellbore contour.The obtained results allowed to determine(i)the drawdowns required to maintain wellbore stability in the given reservoir interval;(ii)the optimal parameters of downhole gravel filter screens for sand control;(iii)to identify the prevailing type of wellbore fracture and to localize failure initiation points on the wellbore walls.The results highlight the importance of integrating modern laboratory core analysis methods to enhance the development of complex reservoirs and reduce the risks of fractures and sand production in weakly cemented formations.
基金the support received from the National Key Research and Development Program of China(Grant No.2023YFB3407400)the National Natural Science Foundation of China(Grant No.52475386,Grant No.52025058).
文摘5xxx Al alloys are widely used in additive manufacturing(AM)components across various industries due to their advantageous properties,including low density,high strength,and excellent corrosion resistance.However,conventional melt-based AM methods often introduce defects such as pores,cracks and elemental evaporation.In the present study,a novel screw extrusion-plasticizing friction stir deposition(SEFSD)process,which enables the extrusion plasticization of 5183 particulate feedstocks via a three-stage tapered screw tool,was utilized to fabricate a 20-layer 5183 deposition wall through continuous linear reciprocating deposition in the solid state.The deposition wall exhibited a refined equiaxed microstructure.Due to the low stacking fault energy(SFE)of Al-Mg alloy,the influence of thermal cycles on microstructural evolution was minimal.Overall,the deposition wall demonstrated excellent mechanical properties,though strength and ductility in the deposition direction were reduced due to interlayer defects,which could be mitigated by incorporating stir pins or enhancing interlayer adhesive friction to intensify the material flow.This study confirms the applicability and significant potential of SEFSD for additive manufacturing 5xxx Al alloy components.
基金supported by the National Natural Science Foundation of China(Nos.52305401 and 52475391)National Key Research and Development Program of China(2024YFB3714301)+1 种基金the Fundamental Research Program of Shanxi Province(202303011211004,TZLH20230818001)Engineering Research Center of the Ministry of Education.
文摘Cold deformation treatment of Cu-bearing stainless steel through a cold rolling process combined with electric pulse treatment(EPT)can significantly improve the microstructure and formability of cold-rolled Cu-bearing stainless steel.The microstructure after EPT was characterized by scanning electron microscopy,transmission electron microscopy,and in-situ tensile testing.It is found that compared with conventional heat treatment,EPT process can significantly promote the nucleation rate and mobility at grain boundaries of the deformed samples,greatly accelerating the recovery and static recrystallization of Cu-bearing stainless steel samples at lower temperatures and contributing to the recovery of anisotropy and the re-molding of deformed samples.Microstructural characterization and theoretical analyses show that the rapid recrystallization during EPT process is caused not only by Joule heating effects but also by non-thermal effects that accelerate grain boundary migration and dislocation destruction and regeneration.In addition,EPT process significantly accelerated the nucleation and precipitation growth of Cu-rich phase.The coarsening of Cu-rich phase during EPT process is due to not only the high vacancy diffusion coefficient under the action of the electric pulse but also the increase in the vacancy diffusion flux induced by the electromigration in the process of the electric pulse.
基金supported by the National Natural Science Foundation of China(Nos.92166105 and 52005053)High-Tech Industry Science and Technology Innovation Leading Program of Hunan Province(No.2020GK2085)the Science and Technology Innovation Program of Hunan Province(No.2021RC3096).
文摘(NbZrHfTi)C high-entropy ceramics,as an emerging class of ultra-high-temperature materials,have garnered significant interest due to their unique multi-principal-element crystal structure and exceptional hightemperature properties.This study systematically investigates the mechanical properties of(NbZrHfTi)C high-entropy ceramics by employing first-principles density functional theory,combined with the Debye-Grüneisen model,to explore the variations in their thermophysical properties with temperature(0–2000 K)and pressure(0–30 GPa).Thermodynamically,the calculated mixing enthalpy and Gibbs free energy confirm the feasibility of forming a stable single-phase solid solution in(NbZrHfTi)C.The calculated results of the elastic stiffness constant indicate that the material meets the mechanical stability criteria of the cubic crystal system,further confirming the structural stability.Through evaluation of key mechanical parameters—bulk modulus,shear modulus,Young’s modulus,and Poisson’s ratio—we provide comprehensive insight into the macro-mechanical behaviour of the material and its correlation with the underlying microstructure.Notably,compared to traditional binary carbides and their average properties,(NbZrHfTi)C exhibits higher Vickers hardness(Approximately 28.5 GPa)and fracture toughness(Approximately 3.4 MPa⋅m^(1/2)),which can be primarily attributed to the lattice distortion and solid-solution strengthening mechanism.The study also utilizes the quasi-harmonic approximation method to predict the material’s thermophysical properties,including Debye temperature(initial value around 563 K),thermal expansion coefficient(approximately 8.9×10^(−6) K−1 at 2000 K),and other key parameters such as heat capacity at constant volume.The results show that within the studied pressure and temperature ranges,(NbZrHfTi)C consistently maintains a stable phase structure and good thermomechanical properties.The thermal expansion coefficient increasing with temperature,while heat capacity approaches the Dulong-Petit limit at elevated temperatures.These findings underscore the potential of(NbZrHfTi)C applications in ultra-high temperature thermal protection systems,cutting tool coatings,and nuclear structural materials.
文摘This study presents a framework involving statistical modeling and machine learning to accurately predict and optimize the mechanical and damping properties of hybrid granite-epoxy(G-E)composites reinforced with cast iron(CI)filler particles.Hybrid G-E composite with added cast iron(CI)filler particles enhances stiffness,strength,and vibration damping,offering enhanced performance for vibration-sensitive engineering applications.Unlike conventional approaches,this work simultaneously employs Artificial Neural Networks(ANN)for highaccuracy property prediction and Response Surface Methodology(RSM)for in-depth analysis of factor interactions and optimization.A total of 24 experimental test data sets of varying input factors(granite weight%,epoxy weight%,and CI filler weight%)were utilized to train and test the prediction models using an ANN approach and further analyze the interaction effects using RSM.Mechanical properties,including tensile,compressive,and flexural strength,elastic modulus,density and damping properties measured under various testing conditions,were set as output parameters for prediction.This study analyzed and optimized the performance of the ANN model using Bayesian Regularization and Levenberg-Marquardt algorithms to identify the best performing number of neurons in the hidden layer for achieving the highest prediction accuracy.The proposed ANN framework achieved an exceptional average determination coefficient(R2)exceeding 99%,with Bayesian Regularization demonstrating remarkable stability in the 22-neuron range and minimal variation across all properties.RSM and ANN form a powerful framework for predicting and optimizing hybrid G-E composite properties,enabling efficient design for vibration-critical applications with reduced experimental effort and performance optimization.
文摘To comprehensively explore the impact of binder content on the mechanical properties of the Polymer bonded explosive(PBX)substitute material(Polymer-bonded Analogue Explosive(PAE)—it is renowned for its outstanding high-temperature resistance,exceptional mechanical properties,excellent chemical stability,and superior electrical insulation),a series of experiments are meticulously carried out.The dynamic and static mechanical properties,along with the microstructure of PAE,are precisely measured through the Split Hopkinson Pressure Bar(SHPB)test,static compression tests,and Scanning Electron Microscopy(SEM).The dynamic performance test outcomes clearly indicate that both the binder content(2%,4%,6%)and temperature(25℃,45℃,70℃)exert a substantial influence on the dynamic mechanical properties of PAE.Specifically,as the binder content increases,the elasticmodulus increases,demonstrating higher stiffness,and the longer failure duration represents a prolonged fracture process rather than an improved deformation strain to failure.This means the strength-related stiffness rises with binder content,but the overall ductility does not increase.Notably,PAE with 2%the Ethylene-Vinyl Acetate Copolymer(EVA)—it bonds well with a variety ofmaterials,such asmetal,wood,and plastic—exhibits distinct plastic deformation behavior,while PAE samples with 4%and 6%EVA display evident brittle fracture characteristics.Additionally,the mechanical properties of PAE are highly sensitive to temperature variations.Among the tested temperatures,PAE showcases the most favorable performance at 45℃.The static performance test results reveal that an increment in binder content effectively helps to reduce the temperature sensitivity of temperature(-40℃,25℃,50℃,70℃)on PAE and enhance its static mechanical properties.The maximum compressive strength gradually diminishes as the temperature rises.However,it should be noted that an excessively high binder content will undermine the mechanical properties of PAE.With the increase in binder content,the compressive modulus demonstrates relatively stable changes under both lowtemperature and high-temperature conditions.The SEM analysis results demonstrate that,aside fromthe initial defects inherent in the material preparation process,the components of PAE are firmly combined.Throughout the tests,no new pores or microcracks emerge,which strongly indicates that the mechanical properties of PAE remain stable.
文摘The high hydrophilicity of pineapple leaf fibres(PALF)limits their use in cement-and gypsum-based composites exposed to moisture.This study evaluates,for the first time,the combined effect of palm kernel oil and beeswax on the hygroscopic resistance and mechanical stability of PALF.The fibres were functionalised with three formulations(oil,wax,and a 1:2 oil/wax blend)applied at different mass ratios(CR=0.5-2).Treatments increased the average bundle diameter by up to+46%(238μm)and reduced density down to 1.06 g/cm^(3).Hygroscopically,water absorption decreased from 202.4%(raw fibres)to 76.3%(CR=2),representing a maximum reduction of 59.4%in saline medium,while moisture regain dropped from 27.9%to 14.6%(−47.7%).The oil/wax blend proved most effective,simultaneously reducing water absorption(−51.2%)and moisture regain(−46.8%)at CR=1.Mechanically,the fibres retained tensile strength(415.2 vs.460.8 MPa,+11%at CR=1)and exhibited enhanced ductility(+62.5%,with elongation at break increasing from 1.6%to 2.6%),without significantly altering Young’s modulus(12.3 to 10 GPa).Water absorption kinetics were accurately described by the Czel and Mohsenin models(R^(2)>0.98).These findings clearly demonstrate that bio-based lipid coatings can provide an eco-friendly alternative to conventional chemical treatments.They improve hygroscopic resistance and preserve mechanical integrity of PALF,providing original quantitative data for their integration into durable cement-and gypsum-based composites subjected to humid or cyclic wet-dry conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272411 and 42007259).
文摘Deep rock engineering is affected by coupled thermo-hydro-mechanical(THM)-dynamic fields,necessitating the elucidation of the dynamic mechanical behavior and failure mechanisms.This study utilized a Multi-field Coupled Controlled Split Hopkinson Pressure Bar(MCC-SHPB)system to elucidate the cross-scale dynamic responses of rocks and the boundaries of failure modes under THM coupling.Impact tests were conducted on green sandstone under coupled conditions of temperature(25℃-80℃),confining pressure(0-15 MPa),and seepage water pressure(0-15 MPa).Scanning electron microscopy(SEM)microstructural characterization and COMSOL Multiphysics numerical simulations were conducted,and a dynamic constitutive theoretical framework and failure-prediction methodology were established.We investigated the impact toughness index(I_(t)),dynamic modulus(E_(d)),dynamic triaxial compressive strength(TCS_(d)),fragmentation degree(W),and failure modes of green sandstone under thermo-confining pressure-seepage-impact loading conditions.The key findings reveal that the(I_(t))reflects different energy regulation mechanisms across different confining pressure regimes.Thermal-microcrack interactions dominate at low pressure,and energy absorption prevails at high pressure.A triphasic dynamic modulus model captures stiffness evolution under energy-driven conditions,revealing cross-scale crack nucleation-propagation and fragment reorganization.The TCSd inflection point signifies energy dissipation shifts,causing nonlinear skeleton bearing-capacity degradation.A critical criterion based on the W was established to distinguish between the two failure modes and predict the unstable failure initiation.Numerical simulations were used to elucidate the effects of inertia-dominated crack propagation and stress wave interference,validating the critical criterion and the predictive accuracy of the theoretical model during cross-scale failure.This study provides a theoretical foundation for assessing the dynamic stability of rock masses subjected to multi-field coupling during deep resource exploitation.
基金supported by the National Natural Science Foundation of China(Grant Nos.51805084 and 52474401)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2023B1515120086 and 2025A1515012873).
文摘The influence of oscillation amplitude on molten pool thermal history,weld morphology characteristics,microstructural evolution,and mechanical properties during laser oscillating welding of QP980 steel was systematically investigated.Results show that laser beam oscillation significantly regulates molten pool thermomechanical behavior through optimized spatial energy distribution,thereby enabling microstructural reconstruction and joint performance enhancement.As the oscillation amplitude increases from 0 to 0.8 mm,the molten pool duration extends to 1.7 times the original value,while peak temperature and average cooling rate decrease by 19%and 39%,respectively.This thermal regulation promotes weld surface width expansion from 0.72 to 1.07 mm.The welding mode undergoes a progressive transition from keyhole mode→transitional mode→conduction mode.This transformation effectively suppresses porosity defects,substantially reducing porosity from 1.8%to 0.15%.Microstructural analysis indicates that oscillation modifies the maximum temperature gradient direction within the molten pool,facilitating preferential growth of coarse columnar grains along the welding centerline to establish load-transfer-favorable crystallographic orientations.The synergistic effects of these factors substantially improve joint mechanical properties:lap joint shear load increases by 81.5%(7.6→13.8 kN),and fracture elongation is enhanced by 135%(0.98→2.3 mm).The operational principles of laser oscillation parameters on the welding quality of QP980 steel were elucidated,providing theoretical foundations for joining process optimization.
基金supported by the National Natural Science Foundation of China(Nos.52471132,52475356,52071139,U21A20130)the National Social Science Fund of China(No.21BJL075)+1 种基金the Natural Science Foundation of Fujian Province for Distinguished Young Scholars,China(No.2024J010031)the Natural Science Foundation of Chongqing,China(No.CSTB2023NSCQ-MSX0886)。
文摘To investigate the complex relationship between rolling process parameters and mechanical properties of AZ31 magnesium alloy rolled sheets,the Leave-One-Out Cross-Validation(LOOCV)and parameter tuning were applied to optimizing hyper-parameters for the four(BPNN,SVR,RF,and KNN)machine learning models.An interpretable prediction model based on machine learning and SHapley Additive exPlanations(SHAP),as well as an analytical method combining the SHAP model and the Pearson Correlation Coefficient(PCC),were proposed.The results showed that among the four models,the SVR model was able to simultaneously and accurately predict the ultimate tensile strength(UTS)and elongation(EL).According to the combination analysis of PCC and the magnesium alloy rolling forming mechanism,it was found that strain rate and reduction displayed a negative and positive correlation with UTS,respectively,while rolling temperature and reduction illustrated a positive and negative correlation with EL,respectively.Through the SHAP method,which could interpret the output results of the SVR machine learning model,it was deduced that reduction and strain rate played an important role in the SVR model of the outputs of the UTS and EL,respectively.Combining SHAP with PCC,it was found that strain rate and reduction had a greater influence on the UTS than rolling temperature,whereas strain rate and rolling temperature had more influence on the EL compared to reduction.
基金supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University(IMSIU)(Grant number IMSIU-DDRSP2603)。
文摘A parametric study was performed to explore the effect of runner thickness,filtration,and hydrogen content on the mechanical properties and defect formation in Al-7%Si-0.3%Mg(2L99)sand castings.A two-level full factorial design of experiments was used to statistically evaluate these parameters and the tensile properties were characterized via Weibull distribution analysis.The findings reveal that decreasing the runner thickness from25 mm to 10 mm and using 10 PPI ceramic filters improve mechanical properties by minimizing double oxide film entrainment as confirmed by electron microscopy examination.In addition,lowering hydrogen concentrations within the Al alloy from 0.24 cm^(3)/100 g Al to 0.12 cm^(3)/100 g Al is also shown to enhance casting integrity by suppressing bifilm inflation and subsequent pore formation.ANOVA results indicate that the hydrogen content is the most important factor,contributing 53%to the variability in mechanical properties,followed by filtration(25%)and runner thickness(17%).The optimized casting conditions including thin runners(10 mm thick),melt filtration,and a low hydrogen level(0.12 cm^(3)/100 g Al),result in an approximately 474%increase in the shape factor and a 107%increase in the characteristic life of UTS,as well as an approximately 413%increase in the shape factor and a 149%increase in characteristic life of elongation.The outcomes suggest that controlled filling systems and melt treatment are critical for producing consistent,high integrity aluminum castings in industrial applications.
基金financially supported by the Shandong Province Natural Science Foundation(No.ZR2023ME181)the National Natural Science Foundation of China(No.52305313)the Natural Science Foundation of Hunan Province(Nos.2023JJ40553 and 2023JJ60433)。
文摘Biodegradable metals(BMs)have shown significant potential for applications in the field of orthopedic implants.These materials gradually degrade after implantation,eventually disappear without residue,provide necessary mechanical support during degradation,and closely integrate with bone tissues.Fe-based BMs are particularly notable for their good mechanical properties and biocompatibility.However,their slow degradation rate is a limitation.The emergence of Mn-incorporated Fe-based alloys(Fe-Mn alloys)offers the possibilities for addressing issues of slow degradation rate and incompatibility of magnetic resonance imaging(MRI)for Fe alloys.This review summarizes the advantages of Fe-Mn alloys as orthopedic implants,and the cutting-edge advances in degradation,mechanical and magnetic properties,and osteogenic performance.The cytotoxicity issue is addressed for the porous structured Fe-Mn alloys caused by the enrichment of manganese ions,and thus the main challenge and the development are involved for the Fe-Mn alloys to achieve a balance among biocompatibility,structure,and degradation rate.Also the perspectives are proposed for Fe-Mn alloys as orthopedic implants.
基金financial support provided by the National Key R&D Program of China(2022YFB3805700)the National Natural Science Foundation of China(Grant Nos.12072094 and 12172106)+1 种基金the open research fund of Suzhou Laboratory(No.SZLAB-1508-2024ZD016)the Self-Planned Task(No.SL20230101)of Songjiang Laboratory,Harbin Institute of Technology。
文摘Snap-through instability-based mechanical metamaterials(SIMMs)with bistability,multistability,negative stiffness,or excellent energy absorption and dissipation performance play an important role in various advanced functional applications.They can serve as energy absorbers,energy dampers,or mechanical memory and logic computing devices,while also providing amplified force output and faster response time in flexible robots,or implementing sensing functions combined with piezoelectric or triboelectric electricity.However,thus far,research on SIMMs that have non-fixed boundary constraints,proactive responsiveness,multi-physical field cross-coupling,and deep information processing capabilities is still facing significant challenges,potentially hindering the development and cross-field comprehensive applications of truly intelligent SIMMs.Our objective is to furnish a concise categorization of SIMMs and offer direction for innovative design and functional implementations.We have emphasized that the non-fixed boundary constraint will expand the design possibilities,while the use of stimulus-responsive materials and 4D printing technology will create novel opportunities for the design of SIMMs.These advancements are expected to achieve innovative mechanical properties and functions.
基金support from the National Key Research and Development Program of China(Grant No.2022YFE0137200)supported by the Taishan Scholars Program and Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety(Grant No.SKLGME023003).
文摘High geo-stress and high temperature in deep rock engineering increase the possibility of engineering and geological disasters in discontinuous rocks.However,the influence of thermomechanical coupling on the shear behavior and damage evolution of prefractured granite remains immature.In this context,true triaxial laboratory tests and discrete element method simulations under different confining pressures(σ3=3 MPa,σ2=4 MPa,andσ3=80 MPa,σ2=100 MPa)and temperatures(25℃-500℃)were carried out on rough granite fractures with two different orientations.Results indicate that high temperature and high confining pressure increase the peak strength of the prefractured specimen,leading to more microcracks in the host rock and more gouges between the surfaces.Thermal strengthening at low temperatures(<300℃)and residual stick-slip only occur under a greater confining pressure for prefractured specimens.High confining pressure suppresses generation of the thermal microcracks in the heating stage.Cracks first initiate in the asperities on the fracture surfaces,and then propagate into the rock matrix during the mechanical loading stage.In addition,prefractured granite with a larger fracture angle is characterized by smaller peak and residual strength,faster residual slip,fewer new cracks on the specimen surface,and a more pronounced thermal strengthening effect on peak strength.The slip tendency analysis indicates that a higher maximum principal stress(s1)and a large fracture angle(45°-75°)generally result in a higher potential for fracture slip or activation.This study will contribute to a better understanding of the fracture shear mechanism under true triaxial thermomechanical coupling conditions and provides new insights into the stability evaluation of deep dynamic geological hazards.
