A comprehensive treatment of fracture of functionally gradedmaterials (FGMs) is provided. It is assumed that the materialproperties depend only on the coordinate perpendicular to the cracksurface And vary continuously...A comprehensive treatment of fracture of functionally gradedmaterials (FGMs) is provided. It is assumed that the materialproperties depend only on the coordinate perpendicular to the cracksurface And vary continuously along the crack faces. By using alaminated composite plate model to simulate the ma- Terialnon-homogeneity, an algorithm for solving the system based on Laplacetransform and Fourier transform Techniques is presented. Unlikeearlier studies that considered certain assumed propertydistributions and a Single crack problem, the current investigationstudies multiple crack problem in the FGMs with arbitrarily Varyingmaterial properties. Transient thermal stresses are presented.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
High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temp...High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temperature upon shear loading.To better understand the shear fracture behavior and underlying processes of intact granite exposed to thermal-mechanical coupling loading,direct shear tests were conducted utilizing a newly built testing apparatus at varied normal stresses and high temperatures.Influencesof different temperatures and different heating methods(real-time heating and thermal treatment)on the shear mechanical behavior were compared and discussed.Results indicate that shear stress fluctuationswith some small stress drops occur as shear stress is approaching the peak strength under real-time heating,accompanied by more and earlier AE signal uprushes.This suggests that greater cracking events occur earlier during real-time heating than after thermal treatment,resulting in a lower peak shear strength.Furthermore,the peak shear strength,post-peak stress drop,and cohesion rise from room temperature(RT)to 200℃(the peak strength increases by 8%,5.8%,and 9.9%under normal stress of 5 MPa,15 MPa,and 20 MPa,correspondingly),and subsequently decline from 200℃to 400℃.Temperature has a limited impact on shear stiffness from RT to 200℃,but significantlyreduces it from 200℃to 400℃,with drops of 15%,7.9%,and 10%under normal stress of 5 MPa,15 MPa,and 20 MPa,respectively.Moreover,the shear strength and stiffness under real-time heating are lower than those for the thermally treated specimens.The strengthening of intact granite below 200℃upon shear is associated with loss of water and a more compacted structure,while the weakening effect of temperature on shear strength from 200℃to 400℃is due to the new thermal cracks and less brittle and stiff of minerals.展开更多
As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operatio...As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.展开更多
Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early os...Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early osteoarthritis(OA),particularly among exercise enthusiasts,remains controversial.Here,we established in vitro and in vivo models of prolonged moderate mechanical loading(7.5%strain,1 Hz)and analyzed human cartilage from weight-bearing and non-weight-bearing regions using RNA sequencing.Prolonged exposure(≥12 h)significantly increased chondrocyte apoptosis(2.3-fold),reduced expression of the chondrogenic transcription factor SOX9 and the matrix markers COL2A1,and elevated nerve growth factor(NGF)expression(1.8-fold),accompanied by enrichment of neural sensitization and inflammatory pathways.Immunofluorescence staining revealed NGF accumulation in mechanically stressed cartilage.Unlike high-intensity stress,which led to immediate apoptosis,moderate loading induced a delayed pro-apoptotic response after 12 h.These findings indicate that prolonged moderate mechanical loading may promote chondrocyte apoptosis through an NGFmediated inflammatory microenvironment and provide mechanistic evidence suggesting that patients with early OA may benefit from limiting high-impact or prolonged moderate-intensity exercise sessions to prevent cartilage damage and guide rehabilitation.展开更多
In electrochemical energy storage systems,the sodium-ion battery is typically integrated in the form of a“cell-module-cluster”,but its cross-scale thermal runaway triggering risk and the propagation mechanism remain...In electrochemical energy storage systems,the sodium-ion battery is typically integrated in the form of a“cell-module-cluster”,but its cross-scale thermal runaway triggering risk and the propagation mechanism remain unclear.This study reveals the cross-scale thermal runaway triggering and propagation behavior of sodium-ion batteries of“cell-module-cluster”under overcharge conditions,and investigates the effects of key factors,including module spacing,triggering cell location,and heat dissipation condition,on the thermal runaway propagation behavior.Results demonstrate that the thermal runaway propagation in a module containing the overcharged cell follows a sequential triggering mode,while thermal runaway in the downstream module exhibits a simultaneous triggering mode with greater severity.Furthermore,increasing the module spacing or enhancing the heat dissipation capacity can effectively reduce the heat accumulation and prevent the trigger of thermal runaway.On the above basis,the multi-dimensional evaluation strategy is proposed to quantitatively assess the hazard of sodium-ion battery cluster thermal runaway.The findings serve as a foundation for the safe design of sodium-ion batteries in energy storage systems.展开更多
Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a ser...Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a series of dynamic compression tests were conducted on granite treated by cyclic thermal shocks at different temperatures.We analyzed the effects of cyclic thermal shock on the thermal-related physical and dynamic mechanical behaviors of granite.Specifically,the P-wave velocity,dynamic strength,and elastic modulus of the tested granite decrease with increasing temperature and cycle number,while porosity and peak strain increase.The degradation law of dynamic mechanical properties could be described by a cubic polynomial.Cyclic thermal shock promotes shear cracks propagation,causing dynamic failure mode of granite to transition from splitting to tensile-shear composite failure,accompanied by surface spalling and debris splashing.Moreover,the thermal shock damage evolution and coupled failure mechanism of tested granite are discussed.The evolution of thermal shock damage with thermal shock cycle numbers shows an obvious S-shaped surface,featured by an exponential correlation with dynamic mechanical parameters.In addition,with increasing thermal shock temperature and cycles,granite mineral species barely change,but the length and width of thermal cracks increase significantly.The non-uniform expansion of minerals,thermal shock-induced cracking,and water-rock interaction are primary factors for deteriorating dynamic mechanical properties of granite under cyclic thermal shock.展开更多
The effects of channel segregation on the macro-and micro-scale chemical composition,microstructure,hardness,and tensile deformation behavior of Ti45Nb wires were investigated.The results show that wires with severe c...The effects of channel segregation on the macro-and micro-scale chemical composition,microstructure,hardness,and tensile deformation behavior of Ti45Nb wires were investigated.The results show that wires with severe channel segregation exhibit a macroscopic chemical composition identical to those without segregation,and 3D X-ray imaging result also reveals no abnormalities.After annealing,both types of wires exhibit an equiaxed single-phase microstructure with comparable grain sizes,suggesting that channel segregation has negligible influence on the macroscopic composition and grain size.Metallographic examination reveals that channel segregation manifests as spot-like features in the transverse section and band-like structures in the longitudinal section.EDS analysis identifies these regions as Ti-enriched segregations,with a Ti content higher than that of the surrounding matrix by approximately 4.42wt%.Compared to segregation-free wires,those containing extensive channel segregation demonstrate a 15.5%increase in ultimate tensile strength and a 12.3%increase in yield strength,but suffer a reduction in elongation and reduction of area by 19.8%and 18.9%,respectively.Furthermore,the mechanical properties of wires with segregation show significant fluctuations.Fractographic analysis reveals a larger fracture surface area in segregated wires.Severe dislocation pile-ups occur at the interfaces of these segregated regions,initiating microcrack nucleation.This promotes rapid crack propagation of the Ti45Nb wire,leading to a significant decrease in plasticity and reduction of area.展开更多
Silicon carbide fibers are considered ideal reinforcing materials for ceramic matrix composites due to their excellent mechanical properties and high-temperature performance.Different types of fibers necessitate indiv...Silicon carbide fibers are considered ideal reinforcing materials for ceramic matrix composites due to their excellent mechanical properties and high-temperature performance.Different types of fibers necessitate individual investigation due to variations in their composition and fabrication processes.This study presents a comprehensive investigation into evolution of the mechanical properties,surface microstructure,and composition of Shicolon-Ⅱ fibers subjected to argon heat treatment at temperatures ranging from 1300℃to 1700℃.The Shicolon-Ⅱ fibers are composed of small-sized β-SiC grains,SiC_(x)O_(y) amorphous phase,and a minor amount of graphite microcrystals.Following treatment in an argon atmosphere at 1300℃,the fibers maintain a monofilament tensile strength of 3.620 GPa,corresponding to a retention of 98.32%.This strength diminishes to 2.875 GPa,equating to a retention of 78.08%,after treatment at 1500℃.The reduction in mechanical properties of the fibers can be ascribed to the decomposition of the amorphous phase and the growth of β-SiC grains.Furthermore,creep resistance is an essential factor influencing the long-term performance of composite materials.After treatment at temperatures above 1400℃,the high-temperature creep resistance of the fibers is significantly enhanced due to growth of β-SiC grains.This study offers valuable theoretical insights into high-temperature applications of second-generation fibers,contributing to an enhanced understanding of their performance under extreme conditions.展开更多
Micrometer-sized,irregularly shaped Ti particles(0.5wt%and 1.0wt%)were mixed with an Al-Si-Mg-Zr matrix powder,and a novel Ti-modified Al-Si-Mg-Zr aluminum alloy was subsequently fabricated via laser-powder bed fusion...Micrometer-sized,irregularly shaped Ti particles(0.5wt%and 1.0wt%)were mixed with an Al-Si-Mg-Zr matrix powder,and a novel Ti-modified Al-Si-Mg-Zr aluminum alloy was subsequently fabricated via laser-powder bed fusion(L-PBF).The results demonstrated that the introduction of Ti particles promoted the formation of near-fully equiaxed grains in the alloy owing to the strong grain refinement of the primary(Al,Si)3(Ti,Zr)nanoparticles.Furthermore,the presence of(Al,Si)3(Ti,Zr)nanoparticles inhibited the decomposition of Si-rich cell boundaries and the precipitation of Si nanoparticles in theα-Al cells.The ultimate tensile strength(UTS),yield strength(YS),and elongation of the asbuilt 0.5wt%Ti(0.5Ti)alloy were(468±11),(350±1)MPa,and(10.0±1.4)%,respectively,which are comparable to those of the L-PBF Al-Si-Mg-Zr matrix alloy and significantly higher than those of traditional L-PBF Al-Si-Mg alloys.After direct aging treatment at 150°C,the precipitation of secondary nanoparticles notably enhanced the strength of the 0.5Ti alloy.Specifically,the 0.5Ti alloy achieved a maximum UTS of(479±11)MPa and YS of(376±10)MPa.At 250°C,the YS of the L-PBF Ti/Al-Si-Mg-Zr alloy was higher than that of the L-PBF Al-Si-Mg-Zr matrix alloy due to the retention of Si-rich cell boundaries,indicating a higher thermal stability.As the aging temperature was increased to 300°C,the dissolution of Si-rich cell boundaries,desolvation of solid-solution elements,and coarsening of nanoprecipitates led to a decrease in the UTS and YS of the alloy to below 300 and 200 MPa,respectively.However,the elongation increased significantly.展开更多
High entropy alloys(HEAs),particularly CoCrNiFeMn system,have emerged as a transformative class of high-performance alloys due to their exceptional mechanical and functional properties.However,traditional manufacturin...High entropy alloys(HEAs),particularly CoCrNiFeMn system,have emerged as a transformative class of high-performance alloys due to their exceptional mechanical and functional properties.However,traditional manufacturing methods for HEAs are limited by inefficiencies and high costs,restricting their widespread applications.Additive manufacturing(AM),specifically laser powder bed fusion(LPBF),offers a promising alternative by enabling the fabrication of HEAs with unique microstructures and enhanced properties.This study investigates the thermal stability and mechanical performance of LPBF-printed CoCrNiFeMn HEA across a wide temperature range.The as-built LPBF HEA with a hierarchically heterogeneous microstructure,featured by columnar grains and ultrafine dislocation cellular structure,demonstrates exceptional thermal stability,with minimal hardness reduction and no apparent recrystallisation even after prolonged exposure to high temperatures(up to 1373 K),in stark contrast to the significant property degradation observed in conventionally processed HEAs.This stability is attributed to the unique dislocation cellular structures and the intrinsic thermal self-stabilizing effects induced by the LPBF process and the inhibition of recrystallisation due to the low stored energy and columnar grain morphology.The LPBF-fabricated HEA also exhibits outstanding strength-ductility synergy across a broad temperature spectrum,with cryogenic deformation enhancing both strength and ductility due to the activation of deformation twinning.At elevated temperatures,the alloy undergoes a slight reduction in strength but retains good ductility,except at 873 K,where a sharp decline in ductility is observed likely due to grain boundary decohesion and porosity-related crack initiation manifested by the cleavage fracture surface and the cracks at grain boundaries.These findings provide new insights into the temperature-dependent mechanical behavior of AM HEAs,highlight the critical role of dislocation cellular structures in achieving superior thermal and mechanical performance,and underscore the potential of additively manufactured HEAs with tailored microstructures for extreme environments.展开更多
Mg alloy matrix composites reinforced with short carbon fibers(C_(sf)/Mg)are considered as potential candidates for integrated structural-functional electronic parts that satisfy the requirements of lightweight,excell...Mg alloy matrix composites reinforced with short carbon fibers(C_(sf)/Mg)are considered as potential candidates for integrated structural-functional electronic parts that satisfy the requirements of lightweight,excellent mechanical properties,and heat dissipation.However,the different characteristics of C_(sf)and Mg alloy make the interface a critical issue affecting the synergistic improvement of thermal and mechanical properties of the composites.Here,Cu coating with different thicknesses is introduced to modify the C_(sf)/Mg interface,so as to simultaneously enhance the thermal and mechanical performances,which can combine the advantages of coating modification and matrix alloying.Results reveal that thermal diffusivity(TD)of 3-C_(sf)-Cu/Mg composites is as high as 22.12 mm^(2)/s and an enhancement of 52.97%is achieved compared with C_(sf)/Mg composites,as well as 16.3%enhancement of ultimate compressive strength(UCS)in the longitudinal direction,8.84%improvement of UCS in the transverse direction,and 53.08%increasement of ultimate tensile strength(UTS).Such improvement can be ascribed to the formation of intermetallic compounds.The formation of intermetallic compounds can not only effectively alleviate the lattice distortion of the matrix and decrease interfacial thermal resistance,but also bear the loads.Our work is of great significance for designing C_(sf)/Mg composites with integrated structure and function.展开更多
With the increasing application of lithium-ion batteries under high-rate operation,safety concerns such as thermal runaway(TR)and thermal runaway propagation(TRP)have become critical.In this study,the TRP action of ba...With the increasing application of lithium-ion batteries under high-rate operation,safety concerns such as thermal runaway(TR)and thermal runaway propagation(TRP)have become critical.In this study,the TRP action of batteries undergoing high-rate cycling is systematically investigated.Microanalysis results reveal that the crystallinity and I_((003))/I_((104))of the cathode are decreased by 32.95%and 13.01%after 4 C cycling,while the layered structure of the anode is seriously damaged.As revealed,the TR interval time(At)of batteries cycled at 4 C is decreased by 83.23%compared with that for batteries cycled at 1 C.Meanwhile,the maximum mass loss(ML)rate of Battery 2#is increased by 32.35%.We have further investigated the influence of battery spacing on TRP action.The maximum TR temperature of Battery2#at 1.5 cm spacing is reduced by 26.21%compared with the value at 0 cm spacing.When increasing the spacing from 0 to 1.5 cm,the ML of batteries is reduced by 20.73%.ML increases and decreases with the elevation of the charging rate and battery spacing,respectively.Compared with a battery cycled at1 C,a battery cycled at 4 C shows reduced heat required to trigger TR.The corresponding decreases can reach 68.28%,70.10%,76.88%,and 26.15%when setting the spacing at 0,0.6,1.5,and 2.1 cm,respectively.This indicates that Battery 2#can enter TR with much lower heat after high-rate cycling.Overall,high-rate cycling and low spacing accelerate the TRP of the battery and aggravate the TR severity of the battery.This work can provide insights for the practical safety design of energy storage systems.展开更多
The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical sim...The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.展开更多
A multi-stimuli-responsive hydrogel,P(VI-co-MAAC-NE),was successfully constructed by covalently integrating the aggregation-induced emission(AIE)moiety(Z)-N-(4-(1-cyano-2-(4-(diethylamino)phenyl)vinyl)-phenyl)methacry...A multi-stimuli-responsive hydrogel,P(VI-co-MAAC-NE),was successfully constructed by covalently integrating the aggregation-induced emission(AIE)moiety(Z)-N-(4-(1-cyano-2-(4-(diethylamino)phenyl)vinyl)-phenyl)methacrylamide(NE)into a dynamic hydrogen-bonding network composed of 1-vinylimidazole(VI)and methacrylic acid(MAAC)groups.The dense hydrogen-bonding network not only provides enhanced mechanical robustness,but also significantly enhances the AIE effect of NE by restricting its molecular motion.Under various external stimuli,the hydrogen bonds within the hydrogel network undergo reversible dissociation and reformation,thus enabling synergistic modulation of the hydrogel’s mechanical properties and luminescence behavior.Specifically,organic solvents disrupt the hydrogen-bonding network and the aggregation of the AIE moiety NE,resulting in macroscopic swelling and fluorescence quenching of the hydrogel.In strongly acidic conditions,protonation of NE molecules suppresses the intramolecular charge transfer(ICT)process,yielding a blue-shifted emission band accompanied by intense blue fluorescence;in highly alkaline environments,deprotonation of carboxyl groups induces hydrogel swelling and disperses NE aggregates,leading to pronounced fluorescence quenching.Moreover,the system exhibits thermally activated shape-memory behavior:heating above the glass transition temperature(T_(g):ca.62℃)softens the hydrogel to allow programmable reshaping,and subsequent hydrogen bond reformation at ambient conditions locks in the resultant geometries without sacrificing the hydrogel’s fluorescence performance.By capitalizing on these multi-stimuli-responsive characteristics and shape-memory behavior,the potential of hydrogel P(VI-co-MAAC-NE)for advanced information encryption and anti-counterfeiting applications is demonstrated.This work not only provides a versatile material platform for sensing and information storage,but also offers new insights into the design of intelligent soft materials integrating AIE features with dynamically regulated supramolecular network structures.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 binder phase performs critically on the comprehensive properties of cemented carbides,especially the hardness(HV)and fracture toughness(K_(IC))relationship.There are strong motivations in both research community a...The binder phase performs critically on the comprehensive properties of cemented carbides,especially the hardness(HV)and fracture toughness(K_(IC))relationship.There are strong motivations in both research community and industry for developing alternative binders to Co in cemented carbide system,due to the reasons such as price instability,property degeneration,and toxicity.Herein,six kinds of high entropy alloys(HEA)including CoCrFeNiMn,CoCrFeMnAl,CoCrFeNiAl,CoCrNiMnAl,CoFeNiMnAl,and CrFeNiMnAl were employed as the alternative binder for the preparation of WC-HEA cemented carbides through mechanical alloying and two-step spark plasma sintering.The impacts of HEA on the microstructures,mechanical properties,and thermal conductivity of WC-HEA hardmetals were determined and discussed.WC-HEA hardmetals exhibited both superior HV and K_(IC)to WC-metal or WC-intermetallic cemented carbides,indicating that HEA alloys were not only harder but also tougher in comparison with traditional metal or intermetallic binders.The HEA bonded hardmetals yielded thermal conductivities much lower than that of traditional WC-Co cemented carbide.The excellent HV-K_(IC)relationship of WC-HEA facilitated the potential engineering structural application of cemented carbides.展开更多
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
Utilization of ceramic wastes to fabricate concrete can not only effectively dispose the wastes,but also reduce the energy and source consumptions.Therefore,we fabricated a green ultra high performance concrete using ...Utilization of ceramic wastes to fabricate concrete can not only effectively dispose the wastes,but also reduce the energy and source consumptions.Therefore,we fabricated a green ultra high performance concrete using ceramic waste powder(CWP)to replace 55%of cement,and ceramic waste aggregate(CWA)to replace 100%natural quartz sand.However,high content of ceramic wastes will harm the concrete performance including workability and mechanical properties.Therefore,a low-cost and low carbon nano-calcium carbonate(NC)was introduced to compensate for the defects caused by large amounts of CWP and CWA to workability and mechanical behavior.The experimental results show that the workability of ultra high performance concrete with large amounts of CWP and CWA(UHPCLCC)increases by 28.57%with NC content of 5%.Moreover,the flexural strengths,fracture energy,compressive strengths,and compressive toughness of UHPCLCC increase up to 29.6%,56.5%,20.4%,and 37.6%,respectively,which is caused by the nano-core effect of NC.展开更多
基金the National Natural Science Foundation of China (Nos.10102004 and 19902003).
文摘A comprehensive treatment of fracture of functionally gradedmaterials (FGMs) is provided. It is assumed that the materialproperties depend only on the coordinate perpendicular to the cracksurface And vary continuously along the crack faces. By using alaminated composite plate model to simulate the ma- Terialnon-homogeneity, an algorithm for solving the system based on Laplacetransform and Fourier transform Techniques is presented. Unlikeearlier studies that considered certain assumed propertydistributions and a Single crack problem, the current investigationstudies multiple crack problem in the FGMs with arbitrarily Varyingmaterial properties. Transient thermal stresses are presented.
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support from the Taishan Scholars Program,Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS),Grant No.ZDBS-LY-DQC022Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Grant No.SKLGME023003.
文摘High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temperature upon shear loading.To better understand the shear fracture behavior and underlying processes of intact granite exposed to thermal-mechanical coupling loading,direct shear tests were conducted utilizing a newly built testing apparatus at varied normal stresses and high temperatures.Influencesof different temperatures and different heating methods(real-time heating and thermal treatment)on the shear mechanical behavior were compared and discussed.Results indicate that shear stress fluctuationswith some small stress drops occur as shear stress is approaching the peak strength under real-time heating,accompanied by more and earlier AE signal uprushes.This suggests that greater cracking events occur earlier during real-time heating than after thermal treatment,resulting in a lower peak shear strength.Furthermore,the peak shear strength,post-peak stress drop,and cohesion rise from room temperature(RT)to 200℃(the peak strength increases by 8%,5.8%,and 9.9%under normal stress of 5 MPa,15 MPa,and 20 MPa,correspondingly),and subsequently decline from 200℃to 400℃.Temperature has a limited impact on shear stiffness from RT to 200℃,but significantlyreduces it from 200℃to 400℃,with drops of 15%,7.9%,and 10%under normal stress of 5 MPa,15 MPa,and 20 MPa,respectively.Moreover,the shear strength and stiffness under real-time heating are lower than those for the thermally treated specimens.The strengthening of intact granite below 200℃upon shear is associated with loss of water and a more compacted structure,while the weakening effect of temperature on shear strength from 200℃to 400℃is due to the new thermal cracks and less brittle and stiff of minerals.
基金funded by Nansha District Science and Technology Project(Grant Number.2024ZD008)funded by China Geological Survey(Grant number:No.DD20230066,DD20242659).
文摘As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.
基金supported by the Zhejiang Medical and Health Innovation Talent Support Project(Grant No.2021RC128 to S.S.)Zhejiang Medicine and Health Science and Technology Project(2025KY1540 to J.J.L.)+3 种基金Zhejiang Province Health Science and Technology Project(2024KY409 and 2021KY1086 to J.Y.L.)Huzhou Science and Technology Planning Project(2020GY10 to W.L.,2022GZ65 to J.Y.L.)Huzhou Basic and Clinical Translation of Orthopedics Key Laboratory(Grant No.HZGKSYS01Y to S.S.)South Taihu Lake Outstanding Young Health Talents Cultivation Program(Grant No.rsk2023001 to S.S.).
文摘Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early osteoarthritis(OA),particularly among exercise enthusiasts,remains controversial.Here,we established in vitro and in vivo models of prolonged moderate mechanical loading(7.5%strain,1 Hz)and analyzed human cartilage from weight-bearing and non-weight-bearing regions using RNA sequencing.Prolonged exposure(≥12 h)significantly increased chondrocyte apoptosis(2.3-fold),reduced expression of the chondrogenic transcription factor SOX9 and the matrix markers COL2A1,and elevated nerve growth factor(NGF)expression(1.8-fold),accompanied by enrichment of neural sensitization and inflammatory pathways.Immunofluorescence staining revealed NGF accumulation in mechanically stressed cartilage.Unlike high-intensity stress,which led to immediate apoptosis,moderate loading induced a delayed pro-apoptotic response after 12 h.These findings indicate that prolonged moderate mechanical loading may promote chondrocyte apoptosis through an NGFmediated inflammatory microenvironment and provide mechanistic evidence suggesting that patients with early OA may benefit from limiting high-impact or prolonged moderate-intensity exercise sessions to prevent cartilage damage and guide rehabilitation.
基金supported by the Anhui Quality Infrastructure Standardization Project(Grant No.2024MKSO7)the Science and Technology Project of State Grid(SGAHDK00DJJS2310027)the Anhui Provincial Natural Science Foundation(Grant No.2208085UD03).
文摘In electrochemical energy storage systems,the sodium-ion battery is typically integrated in the form of a“cell-module-cluster”,but its cross-scale thermal runaway triggering risk and the propagation mechanism remain unclear.This study reveals the cross-scale thermal runaway triggering and propagation behavior of sodium-ion batteries of“cell-module-cluster”under overcharge conditions,and investigates the effects of key factors,including module spacing,triggering cell location,and heat dissipation condition,on the thermal runaway propagation behavior.Results demonstrate that the thermal runaway propagation in a module containing the overcharged cell follows a sequential triggering mode,while thermal runaway in the downstream module exhibits a simultaneous triggering mode with greater severity.Furthermore,increasing the module spacing or enhancing the heat dissipation capacity can effectively reduce the heat accumulation and prevent the trigger of thermal runaway.On the above basis,the multi-dimensional evaluation strategy is proposed to quantitatively assess the hazard of sodium-ion battery cluster thermal runaway.The findings serve as a foundation for the safe design of sodium-ion batteries in energy storage systems.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Grant Nos.52225904 and 52039007)the Natural Science Foundation of Sichuan Province(Grant No.2023NSFSC0377)supported by the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Exploring dynamic mechanical responses and failure behaviors of hot dry rock(HDR)is significant for geothermal exploitation and stability assessment.In this study,via the split Hopkinson pressure bar(SHPB)system,a series of dynamic compression tests were conducted on granite treated by cyclic thermal shocks at different temperatures.We analyzed the effects of cyclic thermal shock on the thermal-related physical and dynamic mechanical behaviors of granite.Specifically,the P-wave velocity,dynamic strength,and elastic modulus of the tested granite decrease with increasing temperature and cycle number,while porosity and peak strain increase.The degradation law of dynamic mechanical properties could be described by a cubic polynomial.Cyclic thermal shock promotes shear cracks propagation,causing dynamic failure mode of granite to transition from splitting to tensile-shear composite failure,accompanied by surface spalling and debris splashing.Moreover,the thermal shock damage evolution and coupled failure mechanism of tested granite are discussed.The evolution of thermal shock damage with thermal shock cycle numbers shows an obvious S-shaped surface,featured by an exponential correlation with dynamic mechanical parameters.In addition,with increasing thermal shock temperature and cycles,granite mineral species barely change,but the length and width of thermal cracks increase significantly.The non-uniform expansion of minerals,thermal shock-induced cracking,and water-rock interaction are primary factors for deteriorating dynamic mechanical properties of granite under cyclic thermal shock.
基金National Natural Science Foundation of China(U24A2038)。
文摘The effects of channel segregation on the macro-and micro-scale chemical composition,microstructure,hardness,and tensile deformation behavior of Ti45Nb wires were investigated.The results show that wires with severe channel segregation exhibit a macroscopic chemical composition identical to those without segregation,and 3D X-ray imaging result also reveals no abnormalities.After annealing,both types of wires exhibit an equiaxed single-phase microstructure with comparable grain sizes,suggesting that channel segregation has negligible influence on the macroscopic composition and grain size.Metallographic examination reveals that channel segregation manifests as spot-like features in the transverse section and band-like structures in the longitudinal section.EDS analysis identifies these regions as Ti-enriched segregations,with a Ti content higher than that of the surrounding matrix by approximately 4.42wt%.Compared to segregation-free wires,those containing extensive channel segregation demonstrate a 15.5%increase in ultimate tensile strength and a 12.3%increase in yield strength,but suffer a reduction in elongation and reduction of area by 19.8%and 18.9%,respectively.Furthermore,the mechanical properties of wires with segregation show significant fluctuations.Fractographic analysis reveals a larger fracture surface area in segregated wires.Severe dislocation pile-ups occur at the interfaces of these segregated regions,initiating microcrack nucleation.This promotes rapid crack propagation of the Ti45Nb wire,leading to a significant decrease in plasticity and reduction of area.
基金National Natural Science Foundation of China(52172108)National Key R&D Program of China(2022YFB3707700)Strategic Priority Research Program of the Chinese Academy of Sciences(XDC0144005)。
文摘Silicon carbide fibers are considered ideal reinforcing materials for ceramic matrix composites due to their excellent mechanical properties and high-temperature performance.Different types of fibers necessitate individual investigation due to variations in their composition and fabrication processes.This study presents a comprehensive investigation into evolution of the mechanical properties,surface microstructure,and composition of Shicolon-Ⅱ fibers subjected to argon heat treatment at temperatures ranging from 1300℃to 1700℃.The Shicolon-Ⅱ fibers are composed of small-sized β-SiC grains,SiC_(x)O_(y) amorphous phase,and a minor amount of graphite microcrystals.Following treatment in an argon atmosphere at 1300℃,the fibers maintain a monofilament tensile strength of 3.620 GPa,corresponding to a retention of 98.32%.This strength diminishes to 2.875 GPa,equating to a retention of 78.08%,after treatment at 1500℃.The reduction in mechanical properties of the fibers can be ascribed to the decomposition of the amorphous phase and the growth of β-SiC grains.Furthermore,creep resistance is an essential factor influencing the long-term performance of composite materials.After treatment at temperatures above 1400℃,the high-temperature creep resistance of the fibers is significantly enhanced due to growth of β-SiC grains.This study offers valuable theoretical insights into high-temperature applications of second-generation fibers,contributing to an enhanced understanding of their performance under extreme conditions.
基金supported by the National Natural Science Foundation of China(Nos.52001140 and 52475361).
文摘Micrometer-sized,irregularly shaped Ti particles(0.5wt%and 1.0wt%)were mixed with an Al-Si-Mg-Zr matrix powder,and a novel Ti-modified Al-Si-Mg-Zr aluminum alloy was subsequently fabricated via laser-powder bed fusion(L-PBF).The results demonstrated that the introduction of Ti particles promoted the formation of near-fully equiaxed grains in the alloy owing to the strong grain refinement of the primary(Al,Si)3(Ti,Zr)nanoparticles.Furthermore,the presence of(Al,Si)3(Ti,Zr)nanoparticles inhibited the decomposition of Si-rich cell boundaries and the precipitation of Si nanoparticles in theα-Al cells.The ultimate tensile strength(UTS),yield strength(YS),and elongation of the asbuilt 0.5wt%Ti(0.5Ti)alloy were(468±11),(350±1)MPa,and(10.0±1.4)%,respectively,which are comparable to those of the L-PBF Al-Si-Mg-Zr matrix alloy and significantly higher than those of traditional L-PBF Al-Si-Mg alloys.After direct aging treatment at 150°C,the precipitation of secondary nanoparticles notably enhanced the strength of the 0.5Ti alloy.Specifically,the 0.5Ti alloy achieved a maximum UTS of(479±11)MPa and YS of(376±10)MPa.At 250°C,the YS of the L-PBF Ti/Al-Si-Mg-Zr alloy was higher than that of the L-PBF Al-Si-Mg-Zr matrix alloy due to the retention of Si-rich cell boundaries,indicating a higher thermal stability.As the aging temperature was increased to 300°C,the dissolution of Si-rich cell boundaries,desolvation of solid-solution elements,and coarsening of nanoprecipitates led to a decrease in the UTS and YS of the alloy to below 300 and 200 MPa,respectively.However,the elongation increased significantly.
基金support from the Australian Centre for Microscopy and Microanalysis(ACMM)as well as the Microscopy Australian node at the University of Sydneysupport from the Australian Research Council under DP23010228,from The University of Sydney under the Robinson Fellowship Scheme and from The University of Sydney Nano Institute under the Kickstarter Funding and Student Ambassador Scholarshipsupport from the National Natural Science Foundation of China(Grant number 52274381).
文摘High entropy alloys(HEAs),particularly CoCrNiFeMn system,have emerged as a transformative class of high-performance alloys due to their exceptional mechanical and functional properties.However,traditional manufacturing methods for HEAs are limited by inefficiencies and high costs,restricting their widespread applications.Additive manufacturing(AM),specifically laser powder bed fusion(LPBF),offers a promising alternative by enabling the fabrication of HEAs with unique microstructures and enhanced properties.This study investigates the thermal stability and mechanical performance of LPBF-printed CoCrNiFeMn HEA across a wide temperature range.The as-built LPBF HEA with a hierarchically heterogeneous microstructure,featured by columnar grains and ultrafine dislocation cellular structure,demonstrates exceptional thermal stability,with minimal hardness reduction and no apparent recrystallisation even after prolonged exposure to high temperatures(up to 1373 K),in stark contrast to the significant property degradation observed in conventionally processed HEAs.This stability is attributed to the unique dislocation cellular structures and the intrinsic thermal self-stabilizing effects induced by the LPBF process and the inhibition of recrystallisation due to the low stored energy and columnar grain morphology.The LPBF-fabricated HEA also exhibits outstanding strength-ductility synergy across a broad temperature spectrum,with cryogenic deformation enhancing both strength and ductility due to the activation of deformation twinning.At elevated temperatures,the alloy undergoes a slight reduction in strength but retains good ductility,except at 873 K,where a sharp decline in ductility is observed likely due to grain boundary decohesion and porosity-related crack initiation manifested by the cleavage fracture surface and the cracks at grain boundaries.These findings provide new insights into the temperature-dependent mechanical behavior of AM HEAs,highlight the critical role of dislocation cellular structures in achieving superior thermal and mechanical performance,and underscore the potential of additively manufactured HEAs with tailored microstructures for extreme environments.
基金supported by the National Natural Science Foundation of China(grant no.52231004 and 52072305).
文摘Mg alloy matrix composites reinforced with short carbon fibers(C_(sf)/Mg)are considered as potential candidates for integrated structural-functional electronic parts that satisfy the requirements of lightweight,excellent mechanical properties,and heat dissipation.However,the different characteristics of C_(sf)and Mg alloy make the interface a critical issue affecting the synergistic improvement of thermal and mechanical properties of the composites.Here,Cu coating with different thicknesses is introduced to modify the C_(sf)/Mg interface,so as to simultaneously enhance the thermal and mechanical performances,which can combine the advantages of coating modification and matrix alloying.Results reveal that thermal diffusivity(TD)of 3-C_(sf)-Cu/Mg composites is as high as 22.12 mm^(2)/s and an enhancement of 52.97%is achieved compared with C_(sf)/Mg composites,as well as 16.3%enhancement of ultimate compressive strength(UCS)in the longitudinal direction,8.84%improvement of UCS in the transverse direction,and 53.08%increasement of ultimate tensile strength(UTS).Such improvement can be ascribed to the formation of intermetallic compounds.The formation of intermetallic compounds can not only effectively alleviate the lattice distortion of the matrix and decrease interfacial thermal resistance,but also bear the loads.Our work is of great significance for designing C_(sf)/Mg composites with integrated structure and function.
基金supported by the National Key Research and Development Plan(2023YFC30099000)the National Natural Science Foundation of China(52104197,52272396,52474233)+2 种基金the Major Basic Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions(2020240521)the Open Fund of the State Key Laboratory of Fire Science(SKLFS)Program(HZ2025-KF03)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX25_0595)。
文摘With the increasing application of lithium-ion batteries under high-rate operation,safety concerns such as thermal runaway(TR)and thermal runaway propagation(TRP)have become critical.In this study,the TRP action of batteries undergoing high-rate cycling is systematically investigated.Microanalysis results reveal that the crystallinity and I_((003))/I_((104))of the cathode are decreased by 32.95%and 13.01%after 4 C cycling,while the layered structure of the anode is seriously damaged.As revealed,the TR interval time(At)of batteries cycled at 4 C is decreased by 83.23%compared with that for batteries cycled at 1 C.Meanwhile,the maximum mass loss(ML)rate of Battery 2#is increased by 32.35%.We have further investigated the influence of battery spacing on TRP action.The maximum TR temperature of Battery2#at 1.5 cm spacing is reduced by 26.21%compared with the value at 0 cm spacing.When increasing the spacing from 0 to 1.5 cm,the ML of batteries is reduced by 20.73%.ML increases and decreases with the elevation of the charging rate and battery spacing,respectively.Compared with a battery cycled at1 C,a battery cycled at 4 C shows reduced heat required to trigger TR.The corresponding decreases can reach 68.28%,70.10%,76.88%,and 26.15%when setting the spacing at 0,0.6,1.5,and 2.1 cm,respectively.This indicates that Battery 2#can enter TR with much lower heat after high-rate cycling.Overall,high-rate cycling and low spacing accelerate the TRP of the battery and aggravate the TR severity of the battery.This work can provide insights for the practical safety design of energy storage systems.
基金Project(51879135)supported by the Taishan Scholars Program,ChinaProject(52309130)supported by the National Natural Science Foundation of China+1 种基金Project(SKLGME023003)supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,ChinaProject(2022AH051754)supported by the Natural Science Research Project of Anhui Universities,China。
文摘The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.
文摘A multi-stimuli-responsive hydrogel,P(VI-co-MAAC-NE),was successfully constructed by covalently integrating the aggregation-induced emission(AIE)moiety(Z)-N-(4-(1-cyano-2-(4-(diethylamino)phenyl)vinyl)-phenyl)methacrylamide(NE)into a dynamic hydrogen-bonding network composed of 1-vinylimidazole(VI)and methacrylic acid(MAAC)groups.The dense hydrogen-bonding network not only provides enhanced mechanical robustness,but also significantly enhances the AIE effect of NE by restricting its molecular motion.Under various external stimuli,the hydrogen bonds within the hydrogel network undergo reversible dissociation and reformation,thus enabling synergistic modulation of the hydrogel’s mechanical properties and luminescence behavior.Specifically,organic solvents disrupt the hydrogen-bonding network and the aggregation of the AIE moiety NE,resulting in macroscopic swelling and fluorescence quenching of the hydrogel.In strongly acidic conditions,protonation of NE molecules suppresses the intramolecular charge transfer(ICT)process,yielding a blue-shifted emission band accompanied by intense blue fluorescence;in highly alkaline environments,deprotonation of carboxyl groups induces hydrogel swelling and disperses NE aggregates,leading to pronounced fluorescence quenching.Moreover,the system exhibits thermally activated shape-memory behavior:heating above the glass transition temperature(T_(g):ca.62℃)softens the hydrogel to allow programmable reshaping,and subsequent hydrogen bond reformation at ambient conditions locks in the resultant geometries without sacrificing the hydrogel’s fluorescence performance.By capitalizing on these multi-stimuli-responsive characteristics and shape-memory behavior,the potential of hydrogel P(VI-co-MAAC-NE)for advanced information encryption and anti-counterfeiting applications is demonstrated.This work not only provides a versatile material platform for sensing and information storage,but also offers new insights into the design of intelligent soft materials integrating AIE features with dynamically regulated supramolecular network structures.
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supported by the National Natural Science Foundation of China(No.52375451)the Shandong Provincial Natural Science Foundation,China(Nos.ZR2023YQ052 and ZR2023ME087)+5 种基金the Shandong Provincial Technological SME Innovation Capability Promotion Project,China(No.2023TSGC0375)the Young Taishan Scholars Program of Shandong Province,China(No.tsqn202306041)the Guangdong Basic and Applied Basic Research Foundation,China(No.2023A1515010044)the Shandong Provincial Youth Innovation Team,China(No.2022KJ038)the Open project of State Key Laboratory of Solid Lubrication,China(No.LSL-22-11)Qilu Youth Scholar Project Funding of Shandong University,China.
文摘The binder phase performs critically on the comprehensive properties of cemented carbides,especially the hardness(HV)and fracture toughness(K_(IC))relationship.There are strong motivations in both research community and industry for developing alternative binders to Co in cemented carbide system,due to the reasons such as price instability,property degeneration,and toxicity.Herein,six kinds of high entropy alloys(HEA)including CoCrFeNiMn,CoCrFeMnAl,CoCrFeNiAl,CoCrNiMnAl,CoFeNiMnAl,and CrFeNiMnAl were employed as the alternative binder for the preparation of WC-HEA cemented carbides through mechanical alloying and two-step spark plasma sintering.The impacts of HEA on the microstructures,mechanical properties,and thermal conductivity of WC-HEA hardmetals were determined and discussed.WC-HEA hardmetals exhibited both superior HV and K_(IC)to WC-metal or WC-intermetallic cemented carbides,indicating that HEA alloys were not only harder but also tougher in comparison with traditional metal or intermetallic binders.The HEA bonded hardmetals yielded thermal conductivities much lower than that of traditional WC-Co cemented carbide.The excellent HV-K_(IC)relationship of WC-HEA facilitated the potential engineering structural application of cemented carbides.
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Funded by the National Science Foundation of China(No.52368031)the China Postdoctoral Science Foundation(No.2022M713497)+1 种基金the Jiangxi Provincial Natural Science Foundation(No.20252BAC250115)the Jiangxi Provincial Department of Transportation Science and Technology Project(No.2022H0017)。
文摘Utilization of ceramic wastes to fabricate concrete can not only effectively dispose the wastes,but also reduce the energy and source consumptions.Therefore,we fabricated a green ultra high performance concrete using ceramic waste powder(CWP)to replace 55%of cement,and ceramic waste aggregate(CWA)to replace 100%natural quartz sand.However,high content of ceramic wastes will harm the concrete performance including workability and mechanical properties.Therefore,a low-cost and low carbon nano-calcium carbonate(NC)was introduced to compensate for the defects caused by large amounts of CWP and CWA to workability and mechanical behavior.The experimental results show that the workability of ultra high performance concrete with large amounts of CWP and CWA(UHPCLCC)increases by 28.57%with NC content of 5%.Moreover,the flexural strengths,fracture energy,compressive strengths,and compressive toughness of UHPCLCC increase up to 29.6%,56.5%,20.4%,and 37.6%,respectively,which is caused by the nano-core effect of NC.
