Nonlinear vibration absorbers have been widely used for vibration suppression of elastic structures,but they were usually placed within the structures.However,designing such a vibration damping device within an engine...Nonlinear vibration absorbers have been widely used for vibration suppression of elastic structures,but they were usually placed within the structures.However,designing such a vibration damping device within an engineering structure is possibly difficult.In this paper,an inertial nonlinear energy sinks(NES)is mounted on the boundaries of the elastic beam to suppress its vibration.Although this vibration suppression approach is more in line with engineering requirements,it introduces nonlinear oscillators at boundaries.This brings certain difficulties to the structural vibration analysis and the optimal absorber design.An approximate analytical approach for the steady-state response is developed in this work and verified by numerical solutions.The comparison with the uncontrolled system demonstrates the high-efficiency vibration suppression of the inertial NES installed on the boundary.Besides,the optimization of the NES parameters is performed.Resonance amplitude of the elastic structure can be reduced by 98%with the optimized NES.In summary,this paper proposes a novel approach to suppress the bending vibration of elastic structures through boundary NESs.The vibration reduction effect is very significant,and it is more feasible to implement.Therefore,this work is helpful to study the vibration of elastic structures with nonlinear boundaries and to promote the application of nonlinear vibration absorbers.展开更多
The optimal design and effectiveness of three control systems,tuned viscous mass damper(TVMD),tuned inerter damper(TID)and tuned mass damper(TMD),on mitigating the seismic responses of base isolated structures,were sy...The optimal design and effectiveness of three control systems,tuned viscous mass damper(TVMD),tuned inerter damper(TID)and tuned mass damper(TMD),on mitigating the seismic responses of base isolated structures,were systematically studied.First,the seismic responses of the base isolated structure with each control system under white noise excitation were obtained.Then,the structural parameter optimizations of the TVMD,TID and TMD were conducted by using three different objectives.The results show that the three control systems were all effective in minimizing the root mean square value of seismic responses,including the base shear of the BIS,the absolute acceleration of structural SDOF,and the relative displacement between the base isolation floor and the foundation.Finally,considering the superstructure as a structural MDOF,a series of time history analyses were performed to investigate the effectiveness and activation sensitivity of the three control systems under far field and near fault seismic excitations.The results show that the effectiveness of TID and TMD with optimized parameters on mitigating the seismic responses of base isolated structures increased as the mass ratio increases,and the effectiveness of TID was always better than TMD with the same mass ratio.The TVMD with a lower mass ratio was more efficient in reducing the seismic response than the TID and TMD.Furthermore,the TVMD,when compared with TMD and TID,had better activation sensitivity and a smaller stroke.展开更多
A two-degree-of-freedom(2DOF)vibration isolation structure with an integrated geometric nonlinear inerter(NI)device is proposed.The device is integrated into an inertial nonlinear energy sink(INES),and its vibration s...A two-degree-of-freedom(2DOF)vibration isolation structure with an integrated geometric nonlinear inerter(NI)device is proposed.The device is integrated into an inertial nonlinear energy sink(INES),and its vibration suppression performance is examined by the Runge-Kutta(RK)method and verified by the harmonic balance method(HBM).The new isolator is compared with a traditional vibration isolator.The results show a significant improvement in the vibration suppression performance.To investigate the effects of the excitation amplitude and initial condition on the dynamics of the system,a series of transmissibility-frequency response analyses are performed based on the displacement transmissibility.The energy flow of the system is analyzed,and numerous calculations reveal a series of ideal values for the energy sink in the NI-INES system.This study provides new insights for the design of vibration isolators.展开更多
Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to...Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to enhance the dynamic performance. The X-structure is used as a mechanism to realize the nonlinear stiffness characteristic of the NES, which can realize the flexibility, adjustability, high efficiency, and easy operation of nonlinear stiffness, and is convenient to apply in the vehicle suspension, and the inerter is applied to replacing the mass of the NES based on the mass amplification characteristic. The dynamic model of the half-vehicle system coupled with the IX-NES is established with the Lagrange theory, and the harmonic balance method(HBM) and the pseudo-arc-length method(PALM) are used to obtain the dynamic response under road harmonic excitation. The corresponding dynamic performance under road harmonic and random excitation is evaluated by six performance indices, and compared with that of the original half-vehicle system to show the benefits of the IX-NES. Furthermore, the structural parameters of the IX-NES are optimized with the genetic algorithm. The results show that for road harmonic and random excitation, using the IX-NES can greatly reduce the resonance peaks and root mean square(RMS) values of the front and rear suspension deflections and the front and rear dynamic tire loads, while the resonance peaks and RMS values of the vehicle body vertical and pitching accelerations are slightly larger.When the structural parameters of the IX-NES are optimized, the vehicle body vertical and pitching accelerations of the half-vehicle system could reduce by 2.41% and 1.16%,respectively, and the other dynamic performance indices are within the reasonable ranges.Thus, the IX-NES combines the advantages of the inerter, X-structure, and NES, which improves the dynamic performance of the half-vehicle system and provides an effective option for vibration attenuation in the vehicle engineering.展开更多
The diagonal inerter is integrated into a suspension vibration reduction system(SVRS).The dynamic model of the SVRS with diagonal inerter and damping is established.The dynamic model is of strong geometric nonlinearit...The diagonal inerter is integrated into a suspension vibration reduction system(SVRS).The dynamic model of the SVRS with diagonal inerter and damping is established.The dynamic model is of strong geometric nonlinearity.The retaining nonlinearity up to cubic terms is validated under impact excitation.The conditions omitting the static deformation are determined.The effects of the diagonal inerter on the vibration reduction performance of the SVRS are explored under impact and random excitations.The vibration reduction performance of the proposed SVRS with both diagonal inerter and damping is better than that of either the SVRS without them or the SVRS with the diagonal damping only.展开更多
When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural dur...When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural durability and ensure the users′comfort level.This study proposed an inerter-based optimal solution to suppress the vibrational forces and energy transmitted to the supporting ground by utilizing the great potential of the inerter.For the external force,which contains various frequency bands,the stochastic response and an energy balance analysis are conducted to evaluate the force transmissibility,structural displacement,and vibration power flow.Given the benefits of the inerter,a transmitted-force-based optimal design framework is proposed for inerter systems,of which the effectiveness is validated by numerical examples.The obtained results show that inerter systems are capable of providing significant reductions in the structural displacement and the force transmitted to the supporting ground.Particularly,the closed-form power equation indicated that a grounded inerter can suppress the force transmission and vibrational energy,thus leading to a less negative impact on the ground and environment.Revealing the working mechanism and optimal design strategy of the inerter can help solve the force-transmission control problem experienced by some practical structures.展开更多
Dynamic impacts such as wind and earthquakes cause loss of life and economic damage.To ensure safety against these effects,various measures have been taken from past to present and solutions have been developed using ...Dynamic impacts such as wind and earthquakes cause loss of life and economic damage.To ensure safety against these effects,various measures have been taken from past to present and solutions have been developed using different technologies.Tall buildings are more susceptible to vibrations such as wind and earthquakes.Therefore,vibration control has become an important issue in civil engineering.This study optimizes tuned mass damper inerter(TMDI)using far-fault ground motion records.This study derives the optimum parameters of TMDI using the Adaptive Harmony Search algorithm.Structure displacement and total acceleration against earthquake load are analyzed to assess the performance of the TMDI system.The effect of the inerter when connected to different floors is observed,and the results are compared to the conventional tuned mass damper(TMD).It is indicated that the case of connecting the inerter force to the 5th floor gives better results.As a result,TMD and TMDI systems reduce the displacement by 21.87%and 25.45%,respectively,and the total acceleration by 25.45%and 19.59%,respectively.These percentage reductions indicated that the structure resilience against dynamic loads can be increased using control systems.展开更多
In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in ...In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in serial or in parallel.The dynamic equations of TID adjacent building damping systems were derived,and the H2 norm criterion was used to optimize and adjust them,so that the system had the optimum damping performance under white noise random excitation.Taking TID frequency ratio and damping ratio as optimization parameters,the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained.The results showed that compared with the classic TMD,TID could obtain a better damping effect in the adjacent buildings.Comparing the TIDs composed of serial or parallel,it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response,while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller.Taking the adjacent building composed of two ten-story frame structures as an example,the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out.It was found that TID had a better damping effect in the full-time range compared with the classic TMD.This paper also studied the potential power of TID in adjacent buildings,which can be converted into available power resources during earthquakes.展开更多
Nonlinear characteristics have demonstrated significant advantages in mitigating vibrations across various engineering applications,particularly in effectively suppressing vibrations over a wide frequency range.This p...Nonlinear characteristics have demonstrated significant advantages in mitigating vibrations across various engineering applications,particularly in effectively suppressing vibrations over a wide frequency range.This paper introduces a novel nonlinear energy sink with a magnetic inerter(MINES).The MINES features a magnetic lead screw that incorporates a pair of helical permanent magnets.When the inner part undergoes linear motion,it is transformed into the rotation of the outer part at a predetermined conversion ratio.Subsequently,the MINES is incorporated into a system with a single degree of freedom,and the corresponding differential equations of motion are derived.The approximate analytical method and the numerical method are used to validate each other.This process clarifies the effectiveness of the MINES in reducing vibrations when subjected to harmonic excitation.The influence of the parameters of the MINES is analyzed.The findings demonstrate that the MINES offers significant benefits in terms of vibration suppression efficiency when the depths of the three barriers are equal.Furthermore,with the increase in excitation amplitude,the MINES enters the nonlinear range,leading to a reduction in system damping.This can effectively prevent the phenomenon of traditional damping stiffening under conditions of high amplitude excitation.Finally,the vibration reduction capability of this nonlinear energy sink was experimentally demonstrated,enhancing its applicability in vibration mitigation.展开更多
As a newly proposed two terminals mechanical element, inerter has been successfully applied in vehicle suspension system to improve its vertical vibration isolation performance. The novelty of this paper is to explore...As a newly proposed two terminals mechanical element, inerter has been successfully applied in vehicle suspension system to improve its vertical vibration isolation performance. The novelty of this paper is to explore the advantages of lateral stability of vehicle suspension by the use of inerter element. A full car model considering the steering condition is built, and the standard fishhook steering input is chosen to test the lateral stability of the suspension system. By considering the ride comfort performance and the rollover resistance performance, three basic suspension layouts incorporating inerter element are optimized by means of genetic algorithm. Constraints of the suspension working space and road holding ability are also taken into account during the optimization. Two steering input condition, namely the sine-steer input and the fishhook steer input are performed to evaluate the vehicle suspension performance. Results show that, the ride comfort and the lateral stability of the vehicle suspension system can be synchronously improved by including the inerter element.展开更多
As a newly proposed two-terminal mechanical element, there are many realizations of inerter such as ball-screw, rack and pinion,hydraulic, fluid and mechatronic inerter. This paper concerns about a novel mechatronic i...As a newly proposed two-terminal mechanical element, there are many realizations of inerter such as ball-screw, rack and pinion,hydraulic, fluid and mechatronic inerter. This paper concerns about a novel mechatronic inerter, which is consisted of a hydraulic piston inerter and linear motor, called hydraulic electric inerter(HEI). Firstly, the structural components and the working principles of two types HEI device are introduced, and the dynamic model of the HEI is established. Then, three classifications of mechatronic inerter, namely, the single motor type, the linear inerter-motor type and the rotary inerter-motor type are presented,and in the meanwhile, some comparisons among the three types mechatronic inerter are analyzed. Subsequently, a methodology of designing and experimental tests of the HEI device is proposed by considering the rated working conditions of the linear motor and the electric elements. At last, the HEI device is conducted, and the force tests of the non-loaded HEI and loaded HEI are tested in order to validate their properties. The experimental results are analyzed, and the discrepancies are also further discussed.展开更多
Replacing the viscous damper of tuned mass damper(TMD)with the proposed inerter-enhanced dampers(IEDs),novel vibration mitigation methods,namely the IED-TMDs,are proposed.Unlike the TMD,which brings only one additiona...Replacing the viscous damper of tuned mass damper(TMD)with the proposed inerter-enhanced dampers(IEDs),novel vibration mitigation methods,namely the IED-TMDs,are proposed.Unlike the TMD,which brings only one additional freedom into the system,the proposed IED-TMDs introduce more freedoms into the considered dynamic system.As a result,the traditional fixed-point theory cannot be used.To address this issue,this paper develops an extended fixed-point theory.Firstly,the inerter and the springs of the IED-TMDs are optimized considering that all four fixed points are of the same height.The closed-form solutions for the optimal inerter and springs of the IED-TMDs are obtained.Secondly,to obtain the optimal damping ratio for the IED-TMDs with multi-fixed points,a new optimization criterion is introduced.Different from the traditional fixed-point theory which controls the slope of the transfer function at the fixed points,the new optimization criterion assumes that the local peaks of the transfer function in between the four fixed points have the same height as the fixed points.And,a flat plateau is achieved in the transfer function.Further,the closed-form solutions for the optimal damping ratio are simplified in consideration of actual applications.Finally,the vibration mitigation performance of the IED-TMDs is evaluated.Results show that the vibration mitigation performance of IED-TMDs is superior to that of the conventional TMD.This superior vibration mitigation performance is more significant for the IED-TMDs with a smaller mass ratio.展开更多
Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-car...Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-carbon emissions and no chlorine gas evolution.The clean production stems from the choice of a molten NaCl-Na_(2)CO_(3) electrolyte to prevent chlorine gas evolution,an inert nickel-based anode to produce oxygen,and a liquid metal cathode to make the cathodic product sit at the bottom of the electrolytic cell.We achieve a current efficiency of>90%for the electrolytic production of liquid Na-Sn alloy.Later,Mg-Sn alloy is prepared using the obtained Na-Sn alloy to displace Mg from molten NaCl-MgCl_(2) with a displacement efficiency of>96%.Further,Na and Mg are separated from the electrolytic Na-Sn and displaced Mg-Sn alloys by vacuum distillation with a recovery rate of>92%and Sn can be reused.Using this electrolysisdisplacement-distillation(EDD)approach,we prepare Mg from seawater.The CO_(2)emission of the EDD approach is~20.6 kg CO_(2)per kg Mg,which is less than that of the Australian Magnesium(AM)electrolysis process(~25.0 kg CO_(2)per kg Mg)and less than half that of the Pidgeon process(~45.2 kg CO_(2)per kg Mg).展开更多
The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion...The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.展开更多
A dual-halide solid electrolyte,Li_(3)YCl_(3)Br_(3),was synthesized using a wet-chemistry route instead of the conventional mechanical ball-milling route.Li_(3)YCl_(3)Br_(3) exhibits an ion conductivity of 2.08 mS/cm ...A dual-halide solid electrolyte,Li_(3)YCl_(3)Br_(3),was synthesized using a wet-chemistry route instead of the conventional mechanical ball-milling route.Li_(3)YCl_(3)Br_(3) exhibits an ion conductivity of 2.08 mS/cm and an electro-chemical stability window of 3.8 V.Additionally,an all-solid-state lithium-ion battery using Li_(3)YCl_(3)Br_(3) and LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(NCM811)as the cathode material achieves a capacity retention of 93%after 200 cycles at 0.3C and maintains a specific capacity of 115 mA·h/g during 2C cycling.This exceptional performance is attributed to the high oxidative stability of Li_(3)YCl_(3)Br_(3) and the in-situ formation of Y_(2)O_(3) inert protective layer on the NCM811 surface under high voltage.Consequently,the study demonstrates the feasibility of a simple,cost-effective wet-chemistry route for synthesizing multi-component halides,highlighting its potential for large-scale production of halide solid electrolytes for practical applications.展开更多
Tungsten inert gas(TIG)welding and laser beam welding(LBW)were employed on as-cast and as-forged Mg−8Li−3Al−2Zn−0.5Y(LAZ832-0.5Y)alloys to investigate their weldability.The microstructure and mechanical properties of ...Tungsten inert gas(TIG)welding and laser beam welding(LBW)were employed on as-cast and as-forged Mg−8Li−3Al−2Zn−0.5Y(LAZ832-0.5Y)alloys to investigate their weldability.The microstructure and mechanical properties of solid solution treated samples were investigated for the purpose of further strength improvement,which were treated at 350℃ for 4 h.The ultimate tensile strength(UTS)and yield strength(YS)of the optimal TIG as-cast alloy welding joint were 159 and 122 MPa,which were obtained under the welding current of 80 A,and were lower than the UTS(184 MPa)and YS(146 MPa)of the optimal LBW as-forged welding joint under the power of 2.1 kW/2.0 kW double-side welding.After the solid solution treatment,on the one hand,the growth ofα-Mg grains in the fusion zone(FZ),heat affected zone(HAZ)and base metal(BM)of both the TIG and LBW welding joints was insignificant.On the other hand,the larger Al_(2)Y phases were still present,while the much smaller white AlLi particles were dissolved into the matrix,leading to the solid solution strengthening of the welding joints.As a result,the UTS and YS of the TIG welding joint respectively increased to 216 and 188 MPa after solid solution treatment,and those of the LBW welding joint only increased to 211 and 160 MPa,respectively.展开更多
CaO-based heat carriers have shown great prospects for thermochemical energy storage in concentrated solar power systems due to the features such as rich reserves,environmental safety,high energy storage densities and...CaO-based heat carriers have shown great prospects for thermochemical energy storage in concentrated solar power systems due to the features such as rich reserves,environmental safety,high energy storage densities and high operation temperatures.However,the density decay because of sintering and poor direct solar absorption of white CaO based heat carriers are the two main obstacles lying on the way to the realistic applications.This work introduced dark Mn-based inert support into calcium heat carriers,attempting to solve the above problems simultaneously.As an inert support,the finely dispersed Ca_(2)MnO_(4) functioned as the metal framework to resist CaCO_(3)/CaO sintering.Consequently,the cyclic stability of CaO-based heat carriers,resulting in the high energy storage densities of~2000 kJ/kg even over 20 cycles.As a dark material,Ca_(2)MnO_(4) successfully darkened CaO-based heat carriers,thereby greatly enhanced the direct solar absorption.In addition,the granulation of CaO-based heat carriers was also studied.The pellets showed satisfactory attrition resistance with only 9.85 wt% mass loss over 3200 cycles.In general,good physicochemical performance of Mn-doped CaO-based heat carrier endows it with great prospects for solar energy storage.展开更多
Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operati...Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operational costs,particularly for hydrocarbons with high boiling points or strong host-vip interactions[2].This is the same case in the newly-developed macrocyclebased crystalline adsorbents,namely nonporous adaptive crystals(NACs).To address these challenges,a recent study published in Angewandte Chemie International Edition by Jie,Ma,and co-workers reported an innovative molecular-"squeeze"triggered desorption mechanism in NACs[3-5].Specifically,ethyl acetate(EA)triggers vip desorption without penetrating the crystal pores or voids.Instead,EA molecules interact with the crystal surface through supramolecular forces,causing the adaptive closure of voids and the subsequent release of vip molecules.Unlike conventional sponges that rely on mechanical squeeze to deform themselves in the bulk for vip release,these macrocycle crystals undergo structural deformation at the molecular level and condensed phase when exposed to vaporized molecules.Because of the similar behavior between sponges and such NACs,the authors name them as sponge-likemacrocyclecrystals.展开更多
The investigation of thermal transport properties of materials has become increasingly important in technological applications,including thermal management and energy conversion.Recently,ultrahigh or low thermal condu...The investigation of thermal transport properties of materials has become increasingly important in technological applications,including thermal management and energy conversion.Recently,ultrahigh or low thermal conductivity has been reported in nitride,boride,and chalcogenide by different strategies.However,the strategy to design oxide crystals with unique thermal properties is also a challenge.In this work,a new ternary oxide crystal Ga_(2)TeO_(6) is designed and expected to show high thermal conductivity due to its lone pairs-free octahedra connected along the caxis by sharing edges.The thermal conductivities of Ga_(2)TeO_(6) crystal are determined to be 19.2 and 23.9Wm^(-1) K^(-1) along the a-and c-axis directions at 323 K,respectively,which are significantly higher than those of most reported oxide crystals.First-principles calculations and crystal structure analyses reveal that the Ga_(2)TeO_(6) crystal shows high sound velocity and weak lattice anharmonicity due to lone pairs-free octahedra and highly symmetric group arrangement.The results suggest that much attention must be paid to the polyhedron with lone pairs and its arrangement in materials design to balance the functions and thermal properties.展开更多
During the tungsten inert gas(TIG)welding process of Ti_(2)AlNb alloy,high heat input leads to the formation of coarse grains,which are detrimental to the mechanical properties of welded joints.To address this problem...During the tungsten inert gas(TIG)welding process of Ti_(2)AlNb alloy,high heat input leads to the formation of coarse grains,which are detrimental to the mechanical properties of welded joints.To address this problem,Ta microalloyed welding wires were developed to enhance the strength of the welded joints.The Ta-modifed fusion zone(FZ)exhibited a well-defned structure with a smooth,defect-free surface.Systematic analysis of the microstructure evolution and mechanical properties of the welded joints revealed that the Ta element completely dissolves into the FZ.During solidifcation,a signifcant constitutional undercooling efect occurs,promoting the columnar-to-equiaxed transition(CET)and reducing grain size from 187.42 to 133.49μm.Mechanical properties tests indicated that with increased Ta content,the strength of the welded joints initially increased and then decreased.When the Ta content in the welding wire was 1 wt%,the joints showed the best performance,with a tensile strength of 909.36 MPa and an elongation of 1.21%.Compared to the welded samples without Ta,the tensile strength and elongation increased by 153.01 MPa and 0.53%,respectively.Grain refnement and increased dislocation density were the main reasons for the improved mechanical properties.However,excessive Ta content led to signifcant the intragrain misorientation,increasing the joint’s anisotropy and causing uneven deformation during tensile testing.Therefore,further addition of Ta did not substantially enhance the tensile properties of the joint.Additionally,the paper provides a detailed analysis of the low elongation observed in the joint.After welding,dislocations were neatly arranged in the FZ,forming numerous parallel dislocation walls,leading to local stress concentration and accelerating crack initiation and propagation.Consequently,the elongation at the weld was lower than that of the base metal(BM).This research ofers a new approach to improve the mechanical properties of Ti2AlNb alloy during welding.展开更多
基金The authors gratefully acknowledge the support of the National Natural Science Foundation of China(Grants 12025204 and 12002217)the Program of Shanghai Municipal Education Commission(Grant 2019-01-07-00-09-E00018)the Key Research Projects of Shanghai Science and Technology Commission(Grant 18010500100).
文摘Nonlinear vibration absorbers have been widely used for vibration suppression of elastic structures,but they were usually placed within the structures.However,designing such a vibration damping device within an engineering structure is possibly difficult.In this paper,an inertial nonlinear energy sinks(NES)is mounted on the boundaries of the elastic beam to suppress its vibration.Although this vibration suppression approach is more in line with engineering requirements,it introduces nonlinear oscillators at boundaries.This brings certain difficulties to the structural vibration analysis and the optimal absorber design.An approximate analytical approach for the steady-state response is developed in this work and verified by numerical solutions.The comparison with the uncontrolled system demonstrates the high-efficiency vibration suppression of the inertial NES installed on the boundary.Besides,the optimization of the NES parameters is performed.Resonance amplitude of the elastic structure can be reduced by 98%with the optimized NES.In summary,this paper proposes a novel approach to suppress the bending vibration of elastic structures through boundary NESs.The vibration reduction effect is very significant,and it is more feasible to implement.Therefore,this work is helpful to study the vibration of elastic structures with nonlinear boundaries and to promote the application of nonlinear vibration absorbers.
基金National Key Research and Development Program of China under Grant No.2017YFC0703600 and No.2017YFC0703604。
文摘The optimal design and effectiveness of three control systems,tuned viscous mass damper(TVMD),tuned inerter damper(TID)and tuned mass damper(TMD),on mitigating the seismic responses of base isolated structures,were systematically studied.First,the seismic responses of the base isolated structure with each control system under white noise excitation were obtained.Then,the structural parameter optimizations of the TVMD,TID and TMD were conducted by using three different objectives.The results show that the three control systems were all effective in minimizing the root mean square value of seismic responses,including the base shear of the BIS,the absolute acceleration of structural SDOF,and the relative displacement between the base isolation floor and the foundation.Finally,considering the superstructure as a structural MDOF,a series of time history analyses were performed to investigate the effectiveness and activation sensitivity of the three control systems under far field and near fault seismic excitations.The results show that the effectiveness of TID and TMD with optimized parameters on mitigating the seismic responses of base isolated structures increased as the mass ratio increases,and the effectiveness of TID was always better than TMD with the same mass ratio.The TVMD with a lower mass ratio was more efficient in reducing the seismic response than the TID and TMD.Furthermore,the TVMD,when compared with TMD and TID,had better activation sensitivity and a smaller stroke.
基金Project supported by the National Natural Science Foundation of China(Nos.12232014 and 12072221)the Fundamental Research Funds for the Central Universities of China(No.2013017)。
文摘A two-degree-of-freedom(2DOF)vibration isolation structure with an integrated geometric nonlinear inerter(NI)device is proposed.The device is integrated into an inertial nonlinear energy sink(INES),and its vibration suppression performance is examined by the Runge-Kutta(RK)method and verified by the harmonic balance method(HBM).The new isolator is compared with a traditional vibration isolator.The results show a significant improvement in the vibration suppression performance.To investigate the effects of the excitation amplitude and initial condition on the dynamics of the system,a series of transmissibility-frequency response analyses are performed based on the displacement transmissibility.The energy flow of the system is analyzed,and numerous calculations reveal a series of ideal values for the energy sink in the NI-INES system.This study provides new insights for the design of vibration isolators.
基金Project supported by the National Natural Science Foundation of China (Nos. 12172153 and51805216)the China Postdoctoral Science Foundation (No. 2023M731668)the Major Project of Basic Science (Natural Science) of the Jiangsu Higher Education Institutions of China(No. 22KJA410001)。
文摘Inspired by the demand of improving the riding comfort and meeting the lightweight design of the vehicle, an inerter-based X-structure nonlinear energy sink(IXNES) is proposed and applied in the half-vehicle system to enhance the dynamic performance. The X-structure is used as a mechanism to realize the nonlinear stiffness characteristic of the NES, which can realize the flexibility, adjustability, high efficiency, and easy operation of nonlinear stiffness, and is convenient to apply in the vehicle suspension, and the inerter is applied to replacing the mass of the NES based on the mass amplification characteristic. The dynamic model of the half-vehicle system coupled with the IX-NES is established with the Lagrange theory, and the harmonic balance method(HBM) and the pseudo-arc-length method(PALM) are used to obtain the dynamic response under road harmonic excitation. The corresponding dynamic performance under road harmonic and random excitation is evaluated by six performance indices, and compared with that of the original half-vehicle system to show the benefits of the IX-NES. Furthermore, the structural parameters of the IX-NES are optimized with the genetic algorithm. The results show that for road harmonic and random excitation, using the IX-NES can greatly reduce the resonance peaks and root mean square(RMS) values of the front and rear suspension deflections and the front and rear dynamic tire loads, while the resonance peaks and RMS values of the vehicle body vertical and pitching accelerations are slightly larger.When the structural parameters of the IX-NES are optimized, the vehicle body vertical and pitching accelerations of the half-vehicle system could reduce by 2.41% and 1.16%,respectively, and the other dynamic performance indices are within the reasonable ranges.Thus, the IX-NES combines the advantages of the inerter, X-structure, and NES, which improves the dynamic performance of the half-vehicle system and provides an effective option for vibration attenuation in the vehicle engineering.
文摘The diagonal inerter is integrated into a suspension vibration reduction system(SVRS).The dynamic model of the SVRS with diagonal inerter and damping is established.The dynamic model is of strong geometric nonlinearity.The retaining nonlinearity up to cubic terms is validated under impact excitation.The conditions omitting the static deformation are determined.The effects of the diagonal inerter on the vibration reduction performance of the SVRS are explored under impact and random excitations.The vibration reduction performance of the proposed SVRS with both diagonal inerter and damping is better than that of either the SVRS without them or the SVRS with the diagonal damping only.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant Nos.2019EEVL03,2019D14 and 2020EEEVL0401National Natural Science Foundation of China under Grant No.51978525National Key R&D Program of China 2021YFE0112200。
文摘When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural durability and ensure the users′comfort level.This study proposed an inerter-based optimal solution to suppress the vibrational forces and energy transmitted to the supporting ground by utilizing the great potential of the inerter.For the external force,which contains various frequency bands,the stochastic response and an energy balance analysis are conducted to evaluate the force transmissibility,structural displacement,and vibration power flow.Given the benefits of the inerter,a transmitted-force-based optimal design framework is proposed for inerter systems,of which the effectiveness is validated by numerical examples.The obtained results show that inerter systems are capable of providing significant reductions in the structural displacement and the force transmitted to the supporting ground.Particularly,the closed-form power equation indicated that a grounded inerter can suppress the force transmission and vibrational energy,thus leading to a less negative impact on the ground and environment.Revealing the working mechanism and optimal design strategy of the inerter can help solve the force-transmission control problem experienced by some practical structures.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP)and the Ministry of Trade,Industry&Energy,Republic of Korea (RS-2024-00441420RS-2024-00442817).
文摘Dynamic impacts such as wind and earthquakes cause loss of life and economic damage.To ensure safety against these effects,various measures have been taken from past to present and solutions have been developed using different technologies.Tall buildings are more susceptible to vibrations such as wind and earthquakes.Therefore,vibration control has become an important issue in civil engineering.This study optimizes tuned mass damper inerter(TMDI)using far-fault ground motion records.This study derives the optimum parameters of TMDI using the Adaptive Harmony Search algorithm.Structure displacement and total acceleration against earthquake load are analyzed to assess the performance of the TMDI system.The effect of the inerter when connected to different floors is observed,and the results are compared to the conventional tuned mass damper(TMD).It is indicated that the case of connecting the inerter force to the 5th floor gives better results.As a result,TMD and TMDI systems reduce the displacement by 21.87%and 25.45%,respectively,and the total acceleration by 25.45%and 19.59%,respectively.These percentage reductions indicated that the structure resilience against dynamic loads can be increased using control systems.
基金This research was funded by the Natural Science Research Project of Higher Education Institutions in Anhui Province(Grant No.2022AH040045)the Anhui Provincial Natural Science Foundation(Grant No.2008085QE245)the Project of Science and Technology Plan of Department of Housing and Urban-Rural Development of Anhui Province(Grant No.2021-YF22).
文摘In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in serial or in parallel.The dynamic equations of TID adjacent building damping systems were derived,and the H2 norm criterion was used to optimize and adjust them,so that the system had the optimum damping performance under white noise random excitation.Taking TID frequency ratio and damping ratio as optimization parameters,the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained.The results showed that compared with the classic TMD,TID could obtain a better damping effect in the adjacent buildings.Comparing the TIDs composed of serial or parallel,it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response,while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller.Taking the adjacent building composed of two ten-story frame structures as an example,the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out.It was found that TID had a better damping effect in the full-time range compared with the classic TMD.This paper also studied the potential power of TID in adjacent buildings,which can be converted into available power resources during earthquakes.
基金supported by the National Natural Science Foundation of China(Grant Nos.62203076,62103065,61922053,62325302,and U2013202)China Postdoctoral Science Foundation(Grant Nos.2021M700584 and 2022M710514)+2 种基金Program of Shanghai Academic/Technology Research Leader(Grant No.21XD1421400)Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyjzdxmX0014)the“Shuguang Program”(18SG36)supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission.
文摘Nonlinear characteristics have demonstrated significant advantages in mitigating vibrations across various engineering applications,particularly in effectively suppressing vibrations over a wide frequency range.This paper introduces a novel nonlinear energy sink with a magnetic inerter(MINES).The MINES features a magnetic lead screw that incorporates a pair of helical permanent magnets.When the inner part undergoes linear motion,it is transformed into the rotation of the outer part at a predetermined conversion ratio.Subsequently,the MINES is incorporated into a system with a single degree of freedom,and the corresponding differential equations of motion are derived.The approximate analytical method and the numerical method are used to validate each other.This process clarifies the effectiveness of the MINES in reducing vibrations when subjected to harmonic excitation.The influence of the parameters of the MINES is analyzed.The findings demonstrate that the MINES offers significant benefits in terms of vibration suppression efficiency when the depths of the three barriers are equal.Furthermore,with the increase in excitation amplitude,the MINES enters the nonlinear range,leading to a reduction in system damping.This can effectively prevent the phenomenon of traditional damping stiffening under conditions of high amplitude excitation.Finally,the vibration reduction capability of this nonlinear energy sink was experimentally demonstrated,enhancing its applicability in vibration mitigation.
基金supported by the National Natural Science Foundation of China(Grant No.51705209)the Natural Science Foundation of Jiangsu Province(Grant No.BK20160533)+1 种基金Scientific Research Innovation Projects of Jiangsu Province(Grant No.KYLX15_1081)Yujie Shen is also supported by the China Scholarship Council
文摘As a newly proposed two terminals mechanical element, inerter has been successfully applied in vehicle suspension system to improve its vertical vibration isolation performance. The novelty of this paper is to explore the advantages of lateral stability of vehicle suspension by the use of inerter element. A full car model considering the steering condition is built, and the standard fishhook steering input is chosen to test the lateral stability of the suspension system. By considering the ride comfort performance and the rollover resistance performance, three basic suspension layouts incorporating inerter element are optimized by means of genetic algorithm. Constraints of the suspension working space and road holding ability are also taken into account during the optimization. Two steering input condition, namely the sine-steer input and the fishhook steer input are performed to evaluate the vehicle suspension performance. Results show that, the ride comfort and the lateral stability of the vehicle suspension system can be synchronously improved by including the inerter element.
基金supported by the China Postdoctoral Science Foundation(Grant No.2019M651723)the National Natural Science Foundation of China(Grant No.51705209)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20160533)the Foundation for Jiangsu Key Laboratory of Traffic and Transportation Security(Grant No.TTS2018-01)
文摘As a newly proposed two-terminal mechanical element, there are many realizations of inerter such as ball-screw, rack and pinion,hydraulic, fluid and mechatronic inerter. This paper concerns about a novel mechatronic inerter, which is consisted of a hydraulic piston inerter and linear motor, called hydraulic electric inerter(HEI). Firstly, the structural components and the working principles of two types HEI device are introduced, and the dynamic model of the HEI is established. Then, three classifications of mechatronic inerter, namely, the single motor type, the linear inerter-motor type and the rotary inerter-motor type are presented,and in the meanwhile, some comparisons among the three types mechatronic inerter are analyzed. Subsequently, a methodology of designing and experimental tests of the HEI device is proposed by considering the rated working conditions of the linear motor and the electric elements. At last, the HEI device is conducted, and the force tests of the non-loaded HEI and loaded HEI are tested in order to validate their properties. The experimental results are analyzed, and the discrepancies are also further discussed.
基金supported by the Beijing Natural Science Foundation(8232010)the Fundamental Research Funds for the Central Universities(2024JBKY002)the National Natural Science Foundation of China(52178269).
文摘Replacing the viscous damper of tuned mass damper(TMD)with the proposed inerter-enhanced dampers(IEDs),novel vibration mitigation methods,namely the IED-TMDs,are proposed.Unlike the TMD,which brings only one additional freedom into the system,the proposed IED-TMDs introduce more freedoms into the considered dynamic system.As a result,the traditional fixed-point theory cannot be used.To address this issue,this paper develops an extended fixed-point theory.Firstly,the inerter and the springs of the IED-TMDs are optimized considering that all four fixed points are of the same height.The closed-form solutions for the optimal inerter and springs of the IED-TMDs are obtained.Secondly,to obtain the optimal damping ratio for the IED-TMDs with multi-fixed points,a new optimization criterion is introduced.Different from the traditional fixed-point theory which controls the slope of the transfer function at the fixed points,the new optimization criterion assumes that the local peaks of the transfer function in between the four fixed points have the same height as the fixed points.And,a flat plateau is achieved in the transfer function.Further,the closed-form solutions for the optimal damping ratio are simplified in consideration of actual applications.Finally,the vibration mitigation performance of the IED-TMDs is evaluated.Results show that the vibration mitigation performance of IED-TMDs is superior to that of the conventional TMD.This superior vibration mitigation performance is more significant for the IED-TMDs with a smaller mass ratio.
基金support from the National Natural Science Foundation of China(No’s.U22B2071,51874211,52031008)the Chilwee Group(CWDY-ZH-YJY-202101-001).
文摘Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-carbon emissions and no chlorine gas evolution.The clean production stems from the choice of a molten NaCl-Na_(2)CO_(3) electrolyte to prevent chlorine gas evolution,an inert nickel-based anode to produce oxygen,and a liquid metal cathode to make the cathodic product sit at the bottom of the electrolytic cell.We achieve a current efficiency of>90%for the electrolytic production of liquid Na-Sn alloy.Later,Mg-Sn alloy is prepared using the obtained Na-Sn alloy to displace Mg from molten NaCl-MgCl_(2) with a displacement efficiency of>96%.Further,Na and Mg are separated from the electrolytic Na-Sn and displaced Mg-Sn alloys by vacuum distillation with a recovery rate of>92%and Sn can be reused.Using this electrolysisdisplacement-distillation(EDD)approach,we prepare Mg from seawater.The CO_(2)emission of the EDD approach is~20.6 kg CO_(2)per kg Mg,which is less than that of the Australian Magnesium(AM)electrolysis process(~25.0 kg CO_(2)per kg Mg)and less than half that of the Pidgeon process(~45.2 kg CO_(2)per kg Mg).
基金financially supported by the Science and Technology Innovation Program of Hunan Province,China(No.2023RC3055)the Natural Science Foundation of Hunan Province,China(Nos.2023JJ30671,2020JJ4114)+5 种基金the Natural Science Foundation of Changsha City,China(No.Kq2208264)National Key Project of Research and Development Plan of China(Nos.2021YFC1910505,2021YFC1910504)the Young Core Teacher Foundation of Hunan Province,China(No.150220001)Key Research and Development Program of Guangdong Province,China(No.2020B010186002)the National Natural Science Foundation of China(No.51601229)the Key-Area Research and Development Program of Foshan City,China(No.2230032004640).
文摘The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.
基金financially supported by Hunan Provincial Science and Technology Department,China(No.2021JJ10058)Key Research and Development Program of Hunan Province,China(No.2023GK2016)。
文摘A dual-halide solid electrolyte,Li_(3)YCl_(3)Br_(3),was synthesized using a wet-chemistry route instead of the conventional mechanical ball-milling route.Li_(3)YCl_(3)Br_(3) exhibits an ion conductivity of 2.08 mS/cm and an electro-chemical stability window of 3.8 V.Additionally,an all-solid-state lithium-ion battery using Li_(3)YCl_(3)Br_(3) and LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(NCM811)as the cathode material achieves a capacity retention of 93%after 200 cycles at 0.3C and maintains a specific capacity of 115 mA·h/g during 2C cycling.This exceptional performance is attributed to the high oxidative stability of Li_(3)YCl_(3)Br_(3) and the in-situ formation of Y_(2)O_(3) inert protective layer on the NCM811 surface under high voltage.Consequently,the study demonstrates the feasibility of a simple,cost-effective wet-chemistry route for synthesizing multi-component halides,highlighting its potential for large-scale production of halide solid electrolytes for practical applications.
基金supported by the National Defense Basic Research Program of China(No.JCKY2023204A005)the Research Program of Joint Research Center of Advanced Spaceflight Technologies of China(No.USCAST2023-3)+2 种基金the National Natural Science Foundation of China(No.U2037601)the Major Scientific and Technological Innovation Project of Luoyang,Henan Province,China(No.2201029A)the Foundation Strengthening Plan Technical Field Fund,China(No.2021-JJ-0112).
文摘Tungsten inert gas(TIG)welding and laser beam welding(LBW)were employed on as-cast and as-forged Mg−8Li−3Al−2Zn−0.5Y(LAZ832-0.5Y)alloys to investigate their weldability.The microstructure and mechanical properties of solid solution treated samples were investigated for the purpose of further strength improvement,which were treated at 350℃ for 4 h.The ultimate tensile strength(UTS)and yield strength(YS)of the optimal TIG as-cast alloy welding joint were 159 and 122 MPa,which were obtained under the welding current of 80 A,and were lower than the UTS(184 MPa)and YS(146 MPa)of the optimal LBW as-forged welding joint under the power of 2.1 kW/2.0 kW double-side welding.After the solid solution treatment,on the one hand,the growth ofα-Mg grains in the fusion zone(FZ),heat affected zone(HAZ)and base metal(BM)of both the TIG and LBW welding joints was insignificant.On the other hand,the larger Al_(2)Y phases were still present,while the much smaller white AlLi particles were dissolved into the matrix,leading to the solid solution strengthening of the welding joints.As a result,the UTS and YS of the TIG welding joint respectively increased to 216 and 188 MPa after solid solution treatment,and those of the LBW welding joint only increased to 211 and 160 MPa,respectively.
基金Project(2024BAB094)supported by the Key Research and Development Program of Hubei Province,ChinaProject(2024040801020296)supported by the Natural Science Foundation of Wuhan City,ChinaProject(52276113)supported by the National Natural Science Foundation of China。
文摘CaO-based heat carriers have shown great prospects for thermochemical energy storage in concentrated solar power systems due to the features such as rich reserves,environmental safety,high energy storage densities and high operation temperatures.However,the density decay because of sintering and poor direct solar absorption of white CaO based heat carriers are the two main obstacles lying on the way to the realistic applications.This work introduced dark Mn-based inert support into calcium heat carriers,attempting to solve the above problems simultaneously.As an inert support,the finely dispersed Ca_(2)MnO_(4) functioned as the metal framework to resist CaCO_(3)/CaO sintering.Consequently,the cyclic stability of CaO-based heat carriers,resulting in the high energy storage densities of~2000 kJ/kg even over 20 cycles.As a dark material,Ca_(2)MnO_(4) successfully darkened CaO-based heat carriers,thereby greatly enhanced the direct solar absorption.In addition,the granulation of CaO-based heat carriers was also studied.The pellets showed satisfactory attrition resistance with only 9.85 wt% mass loss over 3200 cycles.In general,good physicochemical performance of Mn-doped CaO-based heat carrier endows it with great prospects for solar energy storage.
基金the Natural Science Foundation of Jiangsu Province(No.BK20240679)National Natural Science Foundation of China(No.22101134)are greatly acknowledged。
文摘Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operational costs,particularly for hydrocarbons with high boiling points or strong host-vip interactions[2].This is the same case in the newly-developed macrocyclebased crystalline adsorbents,namely nonporous adaptive crystals(NACs).To address these challenges,a recent study published in Angewandte Chemie International Edition by Jie,Ma,and co-workers reported an innovative molecular-"squeeze"triggered desorption mechanism in NACs[3-5].Specifically,ethyl acetate(EA)triggers vip desorption without penetrating the crystal pores or voids.Instead,EA molecules interact with the crystal surface through supramolecular forces,causing the adaptive closure of voids and the subsequent release of vip molecules.Unlike conventional sponges that rely on mechanical squeeze to deform themselves in the bulk for vip release,these macrocycle crystals undergo structural deformation at the molecular level and condensed phase when exposed to vaporized molecules.Because of the similar behavior between sponges and such NACs,the authors name them as sponge-likemacrocyclecrystals.
基金supported by the National Natural Science Foundation of China(No.62175129)the Taishan Scholar of Shandong Province(No.tsqn202306014)the Qilu Young Scholar of Shandong University.
文摘The investigation of thermal transport properties of materials has become increasingly important in technological applications,including thermal management and energy conversion.Recently,ultrahigh or low thermal conductivity has been reported in nitride,boride,and chalcogenide by different strategies.However,the strategy to design oxide crystals with unique thermal properties is also a challenge.In this work,a new ternary oxide crystal Ga_(2)TeO_(6) is designed and expected to show high thermal conductivity due to its lone pairs-free octahedra connected along the caxis by sharing edges.The thermal conductivities of Ga_(2)TeO_(6) crystal are determined to be 19.2 and 23.9Wm^(-1) K^(-1) along the a-and c-axis directions at 323 K,respectively,which are significantly higher than those of most reported oxide crystals.First-principles calculations and crystal structure analyses reveal that the Ga_(2)TeO_(6) crystal shows high sound velocity and weak lattice anharmonicity due to lone pairs-free octahedra and highly symmetric group arrangement.The results suggest that much attention must be paid to the polyhedron with lone pairs and its arrangement in materials design to balance the functions and thermal properties.
基金supported by the National Natural Science Foundation of China(No.52171041)the Science and Technology Special Project(K19168).
文摘During the tungsten inert gas(TIG)welding process of Ti_(2)AlNb alloy,high heat input leads to the formation of coarse grains,which are detrimental to the mechanical properties of welded joints.To address this problem,Ta microalloyed welding wires were developed to enhance the strength of the welded joints.The Ta-modifed fusion zone(FZ)exhibited a well-defned structure with a smooth,defect-free surface.Systematic analysis of the microstructure evolution and mechanical properties of the welded joints revealed that the Ta element completely dissolves into the FZ.During solidifcation,a signifcant constitutional undercooling efect occurs,promoting the columnar-to-equiaxed transition(CET)and reducing grain size from 187.42 to 133.49μm.Mechanical properties tests indicated that with increased Ta content,the strength of the welded joints initially increased and then decreased.When the Ta content in the welding wire was 1 wt%,the joints showed the best performance,with a tensile strength of 909.36 MPa and an elongation of 1.21%.Compared to the welded samples without Ta,the tensile strength and elongation increased by 153.01 MPa and 0.53%,respectively.Grain refnement and increased dislocation density were the main reasons for the improved mechanical properties.However,excessive Ta content led to signifcant the intragrain misorientation,increasing the joint’s anisotropy and causing uneven deformation during tensile testing.Therefore,further addition of Ta did not substantially enhance the tensile properties of the joint.Additionally,the paper provides a detailed analysis of the low elongation observed in the joint.After welding,dislocations were neatly arranged in the FZ,forming numerous parallel dislocation walls,leading to local stress concentration and accelerating crack initiation and propagation.Consequently,the elongation at the weld was lower than that of the base metal(BM).This research ofers a new approach to improve the mechanical properties of Ti2AlNb alloy during welding.
