This paper presents a new type of triangular Sharp Eagle wave energy converter(WEC)platform.On the basis of the linear potential flow theory and the finite element analysis method,the hydrodynamic performance and stru...This paper presents a new type of triangular Sharp Eagle wave energy converter(WEC)platform.On the basis of the linear potential flow theory and the finite element analysis method,the hydrodynamic performance and structural response of the platform are studied,considering the actual platform motion and free surface rise under extreme sea states.First,the effects of the wave frequency and direction on the wave-induced loads and dynamic responses were examined.The motion at a wave direction angle of 0°is relatively low.On this basis,the angle constrained by the two sides of the Sharp Eagle floaters should be aligned with the main wave direction to avoid significant platform motion under extreme sea states.Additionally,the structural response of the platform,including the wave-absorbing floaters,is investigated.The results highlighted that the conditions or locations where yielding,buckling,and fatigue failures occur were different.In this context,the connection area of the Sharp Eagle floaters and platform is prone to yielding failure under oblique wave action,whereas the pontoon and side of the Sharp Eagle floaters are prone to buckling failure during significant vertical motion.Additionally,fatigue damage is most likely to occur at the connection between the middle column on both sides of the Sharp Eagle floaters and the pontoons.The findings of this paper revealed an intrinsic connection between wave-induced loads and the dynamic and structural responses of the platform,which provides a useful reference for the improved design of WECs.展开更多
The afterburning of TNT and structural constraints in confined spaces significantly amplify the blast load,leading to severe structural damage. This study investigates the mechanisms underlying the enhanced dynamic re...The afterburning of TNT and structural constraints in confined spaces significantly amplify the blast load,leading to severe structural damage. This study investigates the mechanisms underlying the enhanced dynamic response of reinforced concrete blast doors with four-sided restraints in confined space. Explosion tests with TNT charges ranging from 0.15 kg to 0.4 kg were conducted in a confined space,capturing overpressure loads and the dynamic response of the blast door. An internal explosion model incorporating the afterburning effect was developed using LS-DYNA software and validated against experimental data. The results reveal that the TNT afterburning effect amplifies both the initial peak overpressure and the quasi-static overpressure, resulting in increased deformation of the blast door.Within the 0.15-0.4 kg charge range, the initial overpressure peak and quasi-static overpressure increased by an average of 1.79 times and 2.21 times, respectively. Additionally, the afterburning effect enhanced the blast door's deflection by 177%. Compared to open-space scenarios, the cumulative deflection of the blast door due to repeated shock wave impacts is significantly greater in confined spaces. Furthermore, the quasi-static pressure arising from the structural constraints sustains the blast door's deflection at a high level.展开更多
The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were ca...The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.展开更多
The solenoid switching valve(SSV)is the key control component of heavy equipment such as continuous casting machines.However,the incompatibility of structural parameters increases the opening and closing time of the S...The solenoid switching valve(SSV)is the key control component of heavy equipment such as continuous casting machines.However,the incompatibility of structural parameters increases the opening and closing time of the SSV.Therefore,this study proposes an optimized design method for an SSV to improve its dynamic performance.First,a multi-physics field-coupling model of the SSV is built,and the effects of different structural parameters on the electromagnetic characteristics are analyzed.After identifying the key influencing parameters,second-order response surface models are established to efficiently predict the opening and closing time.Subsequently,based on the nondominated sorting genetic algorithmⅡ(NSGA-Ⅱ),multi-objective optimization is applied to obtain the Pareto optimal solution of the structural parameters under the double-voltage driving strategy.The structure of the solenoid and valve as well as the dynamic characteristics of the valve are improved.Compared with those before optimization,the optimization results show that the opening and closing time of the optimized SSV are reduced by 24.38%and 51.8%,respectively,and the volume is reduced by 19.7%.The research results and the influence of the solenoid structural parameters on the electromagnetic force provide significant guidance for the design of this type of valve.展开更多
Multi-axle heavy-duty vehicles(MHVs)are essential for military equipment transport due to their safety and stability.However,braking dynamic responses between MHVs and pavement systems still remain underexplored,parti...Multi-axle heavy-duty vehicles(MHVs)are essential for military equipment transport due to their safety and stability.However,braking dynamic responses between MHVs and pavement systems still remain underexplored,particularly regarding their complex load transfer mechanisms.This paper develops an enhanced model of a multi-axle heavy-duty vehicle(MHV)coupled with the uneven and flexible pavement.An advanced coupling iterative method is proposed to solve the highly dimensional equations of the MHV-pavement coupled system.The proposed method was validated through experimental tests,with characteristic parameters of vertical accelerations showing relative errors between 0.42%and 11.80%.The coupling effect and influence mechanism of the braking process are investigated by characteristic parameters of the dynamic responses.Additionally,the influences of braking conditions and pavement parameters are analyzed in time and frequency domains in order to reveal the vibration mechanisms of the coupled system.Moreover,this study establishes a theoretical foundation for monitoring pavement health via vehicle-mounted acceleration signals,which is necessary in military transportation.展开更多
Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain...Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain poorly understood.In this study,finite element method-based numerical simulations were conducted based on the rock slope at Dagangshan Hydropower Station in Sichuan province,China.Firstly,systematic analysis in both the time and frequency domains were performed to examine the seismic dynamic characteristics of the slope.Subsequently,the transfer function method and the multiple stepwise linear regression method were employed to clarify the underlying mechanism and determine critical factors influencing the slope instability during earthquakes.Time-domain analysis reveals that rock slope dynamic response exhibits notable elevation,surface,and local amplification effects.Specifically,the Peak Ground Acceleration(PGA)amplification coefficient(MPGA)is significantly higher at elevated locations,near the slope surface and in areas with protrusions.Moreover,the existence of fracture zones and anti-shear galleries minimally influences the dynamic responses but considerably affect the rupture.Specifically,fracture zones exacerbate rupture,while anti-shear galleries mitigate it.Frequency-domain analysis indicates that the dynamic responses of the slope are closely correlated with the degree of slope rupture.As earthquake magnitude increases,the rupture degree of the slope intensifies,and the dominant frequency of the response within the slope decreases,e.g.,its value shifts from 3.63 to 2.75 Hz at measurement point 9near the slope surface.The transfer function of rock slope,calculated under the excitation of wide flat spectrum white noise can reflect the interrelationships between the inherent properties and the rupture degree.Notably,the peak of the transfer function undergoes inversion as the degree of rupture increases.Furthermore,through multiple stepwise linear regression analysis,four key factors influencing the surface dynamic response of the slope were identified:rock strength,slope angle,elevation,and seismic dominant frequency.These findings provide valuable insights into the underlying mechanisms of rock slope dynamic responses triggered by earthquakes,offering essential guidance for understanding and mitigating seismic impacts on rock slopes.展开更多
In this paper,a new temporal-spatial fractional order model is proposed to study the dynamic behavior of thermo-viscoelastic nanoplates.Traditional singular kernel in Caputo fractional order differentiation is replace...In this paper,a new temporal-spatial fractional order model is proposed to study the dynamic behavior of thermo-viscoelastic nanoplates.Traditional singular kernel in Caputo fractional order differentiation is replaced by the non-singular kernel and thus leads to a new generalized fractional order differential model with the integer order differential models as a special case.This improved model can more flexibly describe small-scale mechanical behavior and time-dependent heat conduction behavior and provides a clear physical explanation for the fractional order parameters.Spatial nonlocal effects are described in terms of nonlocal strain gradient elasticity and spatial fractional order derivatives,while the time-dependent effects are described in terms of non-Fourier heat conduction,viscoelasticity,and time fractional order derivatives.In addition,it is the first time that the nonlocal characteristic lengths and the memory characteristic times are introduced as two new small-scale parameters in the fractional order derivatives of non-singular kernels to focus on the short-range nonlocal behaviors and the short-term memory behaviors.Numerical examples of the free vibration and the forced vibration under step loading are given,and the effects of the spatial fractional order parameter and the temporal fractional order parameter are both discussed.展开更多
During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile str...During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.展开更多
The structural dynamic response reconstruction technology can extract unmeasured information from limited measured data,significantly impacting vibration control,load identification,parameter identification,fault diag...The structural dynamic response reconstruction technology can extract unmeasured information from limited measured data,significantly impacting vibration control,load identification,parameter identification,fault diagnosis,and related fields.This paper proposes a dynamic response reconstruction method based on the Kalman filter,which simultaneously identifies external excitation and reconstructs dynamic responses at unmeasured positions.The weighted least squares method determines the load weighting matrix for excitation identification,while the minimum variance unbiased estimation determines the Kalman filter gain.The excitation prediction Kalman filter is constructed through time,excitation,and measurement updates.Subsequently,the response at the target point is reconstructed using the state vector,observation matrix,and excitation influence matrix obtained through the excitation prediction Kalman filter algorithm.An algorithm for reconstructing responses in continuous system using the excitation prediction Kalman filtering algorithm in modal space is derived.The proposed structural dynamic response reconstruction method evaluates the response reconstruction and the load identification performance under various load types and errors through simulation examples.Results demonstrate the accurate excitation identification under different load conditions and simultaneous reconstruction of target point responses,verifying the feasibility and reliability of the proposed method.展开更多
Underground engineering in extreme environments necessitates understanding rock mechanical behavior under coupled high-temperature and dynamic loading conditions.This study presents an innovative multi-scale cross-pla...Underground engineering in extreme environments necessitates understanding rock mechanical behavior under coupled high-temperature and dynamic loading conditions.This study presents an innovative multi-scale cross-platform PFC-FDEM coupling methodology that bridges microscopic thermal damage mechanisms with macroscopic dynamic fracture responses.The breakthrough coupling framework introduces:(1)bidirectional information transfer protocols enabling seamless integration between PFC’s particle-scale thermal damage characterization and FDEM’s continuum-scale fracture propagation,(2)multi-physics mapping algorithms that preserve crack network geometric invariants during scale transitions,and(3)cross-platform cohesive zone implementations for accurate SHTB dynamic loading simulation.The coupled approach reveals distinct three-stage crack evolution characteristics with temperature-dependent density following an exponential model.High-temperature exposure significantly reduces dynamic strength ratio(60%at 800℃)and diminishes strain-rate sensitivity,with dynamic increase factor decreasing from 1.0 to 2.2(25℃)to 1.0-1.3(800℃).Critically,the coupling methodology captures fundamental energy redistribution mechanisms:thermal crack networks alter elastic energy proportion from 75%to 35%while increasing fracture energy from 5%to 30%.Numerical predictions demonstrate excellent experimental agreement(±8%peak stress-strain errors),validating the PFC-FDEM coupling accuracy.This integrated framework provides essential computational tools for predicting complex thermal-mechanical rock behavior in underground engineering applications.展开更多
The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich i...The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.展开更多
Foamed concrete is widely employed in highway transition sections,due to its lightweight,high-strength,and effective settlement control.It is crucial to investigate its dynamic response linked to the traffic-loading i...Foamed concrete is widely employed in highway transition sections,due to its lightweight,high-strength,and effective settlement control.It is crucial to investigate its dynamic response linked to the traffic-loading influence zone of embankment and transition section smoothness.In this study,in-situ truck tests were conducted in the road-culvert-bridge transition section to obtain the spatio-temporal response patterns.Based on the vertical response,the influence zone was ascertained.Depending on the longitudinal response,the smoothness was evaluated by equivalent dynamic stiffness(EDS)and acceleration variation rate(AVR).Furthermore,the response discrepancies of embankments with different fillings were compared.Findings reveal exponential attenuation of dynamic stress and acceleration with increasing depth.The acceleration and dynamic displacement exhibit U-shaped patterns in the culvert subsection and abrupt changes in the bridgehead subsection.The influence zone determined by the acceleration attenuation coefficient method,dynamic stress attenuation method,and stress diffusion angle method was 1.55 m,2.05 m,and 2.89 m,respectively.The maximum disparity in EDS occurs at the culvert subsection and bridge abutment,and the AVR ranges from 0 to 0.52 s^(-2).Moreover,94.1%attenuation of the dynamic stress occurred within the 1.5-meter foamed concrete embankment under the setting of 100 kN-60 km/h.展开更多
Low collateral damage weapons achieve controlled personnel injury through the coupling of shock waves and particle swarms,where the particle swarms arise from the high-explosive dispersion of compacted metal particle ...Low collateral damage weapons achieve controlled personnel injury through the coupling of shock waves and particle swarms,where the particle swarms arise from the high-explosive dispersion of compacted metal particle ring.To investigate the dynamic response of the human target under combined shock waves and particle swarms loading,a physical human surrogate torso model(HSTM)was developed,and the dynamic response test experiment was conducted under the combined loading.The effects of particle size on the loading parameters,the damage patterns of the ballistic plate and HSTM,and the dynamic response parameters of the HSTM with and without protection are mainly analyzed.Our findings revealed that particle swarms can effectively delay the shock wave attenuation,especially the best effect when the particle size was 0.28–0.45 mm.The ballistic plate mainly exhibited dense perforation of the outer fabric and impacted crater damage of ceramic plates,whereas the unprotected HSTM was mainly dominated by high-density and small-size ballistic cavity group damage.The peak values of the dynamic response parameters for the HSTM under combined loading were significantly larger than those under bare charge loading,with multiple peaks observed.Under unprotected conditions,the peak acceleration of skeletons and peak pressure of organs increased with the particle size.Under protected conditions,the particle size,the number of particles hit,and the fit of the ballistic plate to the HSTM together affected the dynamic response parameters of the HSTM.展开更多
This study designs four types of liquid-filled cylindrical shell structures to investigate their protection characteristics against explosive shock waves and high-speed fragments.Bare charge and charge-driven prefabri...This study designs four types of liquid-filled cylindrical shell structures to investigate their protection characteristics against explosive shock waves and high-speed fragments.Bare charge and charge-driven prefabricated fragments are employed to examine the damage under blast shock waves and combined blast and fragments loading on various liquid-filled cylindrical shell structures.The test results are compared to numerical calculations and theoretical analysis for the structure's deformation,the liquid medium's movement,and the pressure waves'propagation characteristics under different liquid-filling methods.The results showed that the filling method influences the blast protection and the struc-ture's energy absorption performance.The external filling method reduces the structural deformation,and the internal filling method increases the damage effect.The gapped internal filling method improves the structure's energy absorption efficiency.The pressure wave loading on the liquid-filled cylindrical shell structure differs depending on filling methods.Explosive shock waves and high-speed fragments show a damage enhancement effect on the liquid-filled cylindrical shell structure,depending on the thickness of the internal liquid container layer.The specific impulse on the inner surface of the cylindrical shell positively correlates to the radial deformation of the cylindrical shell structure,and the external liquid layer limits the radial structural deformation.展开更多
Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to th...Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to the concealment nature of interfacial interactions.This study establishes an equivalent shear model for a bolt-resin-rock anchoring system and conducts direct shear tests under dynamic normal load(DNL)boundary from both laboratory experiments and discrete element method(DEM)simulations.The research investigates the influence of normal dynamic load amplitude(An)and rock type on shear strength parameters,elucidating the evolutionary characteristics and underlying mechanisms of shear load and normal displacement fluctuations induced by cyclic normal loading,with maximum shear load decreasing by 36.81%to 46.94%as An increases from 10%to 70%when rock type varies from coal to limestone.Through analysis of strain field evolution,the critical impact of rock type on localization of shear failure surface is revealed,with systematic summarization of differentiated wear characteristics,failure modes,and key controlling factors associated with shear failure surface.Mesoscopic investigations enabled by DEM simulations uncover the nonuniform distribution of contact force chains within the material matrix and across the anisotropic interfaces under various DNL boundaries,clarify rock type dependent crack propagation pathways,and quantitatively assess the damage extent of shear failure surface,with the anisotropic interface damage factor increasing from 34.9%to 56.6%as An rises from 10%to 70%,and decreasing from 49.6%to 23.4%as rock type varies from coal to limestone.展开更多
Steep bedding slopes are widely distributed in Southwestern China’s mountainous regions and have complex seismic responses and instability risks,causing casualties and property losses.Considering the high-seismic-int...Steep bedding slopes are widely distributed in Southwestern China’s mountainous regions and have complex seismic responses and instability risks,causing casualties and property losses.Considering the high-seismic-intensity environment,the dynamic failure evolution and instability mechanism of high-steep bedding slopes are simulated via the discrete element method and shaking table test.The dynamic response characteristics and cumulative failure effects of slopes subjected to continuous ground motion are investigated.The results show that the dynamic response characteristics of slopes under continuous earthquakes are influenced by geological and topographic conditions.Elevation has a distinct impact on both the slope interior and surface,with amplification effects more pronounced on the surface.The weak interlayers have different influences on the dynamic amplification effect of slopes.Weak interlayers have dynamic magnification effects on the slope surface at relative elevations of 0-0.33 and 0.82-1.0 but have weakening effects between 0.33 and 0.82.Moreover,the weak interlayers also have controlling effects on the dynamic instability mode of slopes.The characteristics of intergranular contact failure,fracture propagation,and displacement distribution are analyzed to reveal the dynamic failure evolution and instability mechanism through the discrete-element model.The dynamic instability process of slopes includes three stages:fracture initiation(0-0.2g),fracture expansion(0.2g-0.3g),and sliding instability(0.3g-0.6g).This work can provide a valuable reference for the seismic stability and reinforcement of complex slopes.展开更多
Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density ...Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density functional theory(DFT)calculations,researchers can investigate gas sensing mechanisms,optimize,and predict the electronic structures and response characteristics of these materials,and thereby identify candidate materials with promising gas sensing applications for targeted design.This review concentrates on three primary applications of DFT technology in the realm of organic semiconductor-based gas sensors:(1)Investigating the sensing mechanisms by analyzing the interactions between gas molecules and sensing materials through DFT,(2)simulating the dynamic responses of gas molecules,which involves the behavior on the sensing interface using DFT combined with other computational methods to explore adsorption and diffusion processes,and(3)exploring and designing sensitive materials by employing DFT for screening and predicting chemical structures,thereby developing new sensing materials with exceptional performance.Furthermore,this review examines current research outcomes and anticipates the extensive application prospects of DFT technology in the domain of organic semiconductor-based gas sensors.These efforts are expected to provide valuable insights for further indepth exploration of DFT applications in sensor technology,thereby fostering significant advancements and innovations in the field.展开更多
The dynamic response characteristics of scoliosis and kyphosis to vibration are currently unclear.The finite element method(FEM)was employed to study the vibration response of patients with idiopathic scoliosis and ky...The dynamic response characteristics of scoliosis and kyphosis to vibration are currently unclear.The finite element method(FEM)was employed to study the vibration response of patients with idiopathic scoliosis and kyphosis.The objective is to analyze the dynamic characteristics of idiopathic scoliosis and kyphosis using FEM.The finite element model of T1—S1 segments was established and verified using the CT scanning images.The established scoliosis and kyphosis models were verified statistically and dynamically.The finite element software Abaqus was utilized to analyze the mode,harmonic response,and transient dynamics of scoliosis and kyphosis.The first four natural frequencies extracted from modal analysis were 1.34,2.26,4.49 and 17.69 Hz respectively.Notably,the first three natural frequencies decreased with the increase of upper body mass.In harmonic response analysis,the frequency corresponding to the maximum amplitude in x direction was the first order natural frequency,and the frequency corresponding to the maximum amplitude in y and z directions was the second order natural frequency.At the same resonance frequency,the amplitude of the thoracic spine was larger relative to that of the lumbar spine.The time domain results of transient analysis showed that the displacement dynamic response of each segment presented cyclic response characteristics over time.Under 2.26 Hz excitation,the dynamic response of the research object appeared as resonance.The higher the degree of spinal deformity,the greater the fundamental frequency.The first three natural modes of scoliosis and kyphosis contain vibration components in the vertical direction.The second order natural frequency was the most harmful to patients with scoliosis and kyphosis.Under cyclic loading,the deformation of the thoracic cone exceeds that of the lumbar cone.展开更多
This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes th...This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes the most representative models and methods of analysis in the existing literature and illustrates all of them by numerical examples.Thus,13 such examples are presented here in some detail.Both flexible and rigid(concrete)pavement models involving simple and elaborate cases with respect to geometry and material behavior are considered.Thus,homogeneous or layered half-spaces with isotropic or cross-anisotropic and elastic,viscoelastic or poroelastic properties are considered.The vehicles are modeled as simple point or distributed loads or discrete spring-mass-dashpot system moving with constant or variable velocity.The dynamic response of the above pavement-vehicle systems is obtained by analytical/numerical or purely numerical methods of solution.Analytical/numerical methods have mainly to do with Fourier transforms or complex Fourier series with respect to both space and time.Purely numerical methods involve the finite element method(FEM)and the boundary element method(BEM)working in time or frequency domain.Critical discussions on the advantages and disadvantages of the various pavement-vehicle models and their methods of analysis are provided and the effects of the main parameters on the pavement response are determined through parametric studies and presented in the examples.Finally,conclusions are provided and suggestions for future research are made.展开更多
In the aerospace sector,the soft magnetic materials of Hermetically Sealed Electromagnetic Relays(HSERs)are critical in forming magnetic circuits.Conventional soft magnetic materials,primarily magnetic iron,have been ...In the aerospace sector,the soft magnetic materials of Hermetically Sealed Electromagnetic Relays(HSERs)are critical in forming magnetic circuits.Conventional soft magnetic materials,primarily magnetic iron,have been unable to meet the development trend of fast-response,miniaturized,and lightweight aerospace and aviation systems.This paper applies circuit theory and electromagnetics theory to establish a Field-Circuit Coupling Mathematical Model(FCCMM)for dynamic response analysis of HSERs.This model centers on inductance calculation,with the core's permeability and saturation magnetic flux density as critical parameters.Based on this model,for a specific type of HSER,this paper introduced three alloys with key parameters different from magnetic iron,then tested the magnetic characteristic curves of these four soft magnetic materials,followed by simulations to obtain the electromagnetic characteristics of digital mock-ups corresponding to these four materials,compared and validated the dynamic responses corresponding to these four soft magnetic materials finally.Based on the theoretical model analysis results,this paper designed a lightweight coil to minimize response time,made prototypes,set up test systems,and tested dynamic characteristics.The experimental results indicate that the nanocrystalline alloy1K107B exhibits the most significant optimization,reducing the closing time by 40.48%and achieving a weight reduction of 6.53%.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC3003805)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2022356)Guangzhou Basic and Applied Basic Research Project(Grant No.2023A04J0955).
文摘This paper presents a new type of triangular Sharp Eagle wave energy converter(WEC)platform.On the basis of the linear potential flow theory and the finite element analysis method,the hydrodynamic performance and structural response of the platform are studied,considering the actual platform motion and free surface rise under extreme sea states.First,the effects of the wave frequency and direction on the wave-induced loads and dynamic responses were examined.The motion at a wave direction angle of 0°is relatively low.On this basis,the angle constrained by the two sides of the Sharp Eagle floaters should be aligned with the main wave direction to avoid significant platform motion under extreme sea states.Additionally,the structural response of the platform,including the wave-absorbing floaters,is investigated.The results highlighted that the conditions or locations where yielding,buckling,and fatigue failures occur were different.In this context,the connection area of the Sharp Eagle floaters and platform is prone to yielding failure under oblique wave action,whereas the pontoon and side of the Sharp Eagle floaters are prone to buckling failure during significant vertical motion.Additionally,fatigue damage is most likely to occur at the connection between the middle column on both sides of the Sharp Eagle floaters and the pontoons.The findings of this paper revealed an intrinsic connection between wave-induced loads and the dynamic and structural responses of the platform,which provides a useful reference for the improved design of WECs.
基金financially supported by the National Natural Science Foundation of China (Grant No. 52278504)the Natural Science Foundation of Jiangsu Province (Grant No. BK20220141)。
文摘The afterburning of TNT and structural constraints in confined spaces significantly amplify the blast load,leading to severe structural damage. This study investigates the mechanisms underlying the enhanced dynamic response of reinforced concrete blast doors with four-sided restraints in confined space. Explosion tests with TNT charges ranging from 0.15 kg to 0.4 kg were conducted in a confined space,capturing overpressure loads and the dynamic response of the blast door. An internal explosion model incorporating the afterburning effect was developed using LS-DYNA software and validated against experimental data. The results reveal that the TNT afterburning effect amplifies both the initial peak overpressure and the quasi-static overpressure, resulting in increased deformation of the blast door.Within the 0.15-0.4 kg charge range, the initial overpressure peak and quasi-static overpressure increased by an average of 1.79 times and 2.21 times, respectively. Additionally, the afterburning effect enhanced the blast door's deflection by 177%. Compared to open-space scenarios, the cumulative deflection of the blast door due to repeated shock wave impacts is significantly greater in confined spaces. Furthermore, the quasi-static pressure arising from the structural constraints sustains the blast door's deflection at a high level.
基金supported by the National Natural Science Foundation of China (Grant No.52109125)the Natural Science Foundation of Jiangsu Province,China (Grant No.BK20231217)the Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Chinese Academy of Sciences (Grant No.SKLGME023001).
文摘The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.
基金Supported by National Natural Science Foundation of China(Grant No.2018YFB1703000)State Key Laboratory of Metal Extrusion and Forging Equipment TechnologyChina National Heavy Machinery Research Institute Co.,Ltd.(Grant No.B2408100.W19)。
文摘The solenoid switching valve(SSV)is the key control component of heavy equipment such as continuous casting machines.However,the incompatibility of structural parameters increases the opening and closing time of the SSV.Therefore,this study proposes an optimized design method for an SSV to improve its dynamic performance.First,a multi-physics field-coupling model of the SSV is built,and the effects of different structural parameters on the electromagnetic characteristics are analyzed.After identifying the key influencing parameters,second-order response surface models are established to efficiently predict the opening and closing time.Subsequently,based on the nondominated sorting genetic algorithmⅡ(NSGA-Ⅱ),multi-objective optimization is applied to obtain the Pareto optimal solution of the structural parameters under the double-voltage driving strategy.The structure of the solenoid and valve as well as the dynamic characteristics of the valve are improved.Compared with those before optimization,the optimization results show that the opening and closing time of the optimized SSV are reduced by 24.38%and 51.8%,respectively,and the volume is reduced by 19.7%.The research results and the influence of the solenoid structural parameters on the electromagnetic force provide significant guidance for the design of this type of valve.
基金National Defense Basic Scientific Research Program of China(Grant No.JCKY2021602B030).
文摘Multi-axle heavy-duty vehicles(MHVs)are essential for military equipment transport due to their safety and stability.However,braking dynamic responses between MHVs and pavement systems still remain underexplored,particularly regarding their complex load transfer mechanisms.This paper develops an enhanced model of a multi-axle heavy-duty vehicle(MHV)coupled with the uneven and flexible pavement.An advanced coupling iterative method is proposed to solve the highly dimensional equations of the MHV-pavement coupled system.The proposed method was validated through experimental tests,with characteristic parameters of vertical accelerations showing relative errors between 0.42%and 11.80%.The coupling effect and influence mechanism of the braking process are investigated by characteristic parameters of the dynamic responses.Additionally,the influences of braking conditions and pavement parameters are analyzed in time and frequency domains in order to reveal the vibration mechanisms of the coupled system.Moreover,this study establishes a theoretical foundation for monitoring pavement health via vehicle-mounted acceleration signals,which is necessary in military transportation.
基金supported by the National Natural Science Foundation of China(Grant Nos.52274075,42122052,52379098)。
文摘Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain poorly understood.In this study,finite element method-based numerical simulations were conducted based on the rock slope at Dagangshan Hydropower Station in Sichuan province,China.Firstly,systematic analysis in both the time and frequency domains were performed to examine the seismic dynamic characteristics of the slope.Subsequently,the transfer function method and the multiple stepwise linear regression method were employed to clarify the underlying mechanism and determine critical factors influencing the slope instability during earthquakes.Time-domain analysis reveals that rock slope dynamic response exhibits notable elevation,surface,and local amplification effects.Specifically,the Peak Ground Acceleration(PGA)amplification coefficient(MPGA)is significantly higher at elevated locations,near the slope surface and in areas with protrusions.Moreover,the existence of fracture zones and anti-shear galleries minimally influences the dynamic responses but considerably affect the rupture.Specifically,fracture zones exacerbate rupture,while anti-shear galleries mitigate it.Frequency-domain analysis indicates that the dynamic responses of the slope are closely correlated with the degree of slope rupture.As earthquake magnitude increases,the rupture degree of the slope intensifies,and the dominant frequency of the response within the slope decreases,e.g.,its value shifts from 3.63 to 2.75 Hz at measurement point 9near the slope surface.The transfer function of rock slope,calculated under the excitation of wide flat spectrum white noise can reflect the interrelationships between the inherent properties and the rupture degree.Notably,the peak of the transfer function undergoes inversion as the degree of rupture increases.Furthermore,through multiple stepwise linear regression analysis,four key factors influencing the surface dynamic response of the slope were identified:rock strength,slope angle,elevation,and seismic dominant frequency.These findings provide valuable insights into the underlying mechanisms of rock slope dynamic responses triggered by earthquakes,offering essential guidance for understanding and mitigating seismic impacts on rock slopes.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072022 and 11872105)Fundamental Research Funds for the Central Universities(Grant Nos.FRF-TW-2018-005 and FRF-BR-18-008B).
文摘In this paper,a new temporal-spatial fractional order model is proposed to study the dynamic behavior of thermo-viscoelastic nanoplates.Traditional singular kernel in Caputo fractional order differentiation is replaced by the non-singular kernel and thus leads to a new generalized fractional order differential model with the integer order differential models as a special case.This improved model can more flexibly describe small-scale mechanical behavior and time-dependent heat conduction behavior and provides a clear physical explanation for the fractional order parameters.Spatial nonlocal effects are described in terms of nonlocal strain gradient elasticity and spatial fractional order derivatives,while the time-dependent effects are described in terms of non-Fourier heat conduction,viscoelasticity,and time fractional order derivatives.In addition,it is the first time that the nonlocal characteristic lengths and the memory characteristic times are introduced as two new small-scale parameters in the fractional order derivatives of non-singular kernels to focus on the short-range nonlocal behaviors and the short-term memory behaviors.Numerical examples of the free vibration and the forced vibration under step loading are given,and the effects of the spatial fractional order parameter and the temporal fractional order parameter are both discussed.
基金sponsored by Natural Science Research Project of Anhui Educational Committee(GrantNo.2022AH050810),NationalNatural Science Foundation of China(GrantNos.42402276,41972286,42072309,42102329)State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,Jianghan University(No.PBSKL2023A1)the Open Fund of National Center for International Research on Deep Earth Drilling and Resource Development(No.DEDRD-2023-02).
文摘During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.
基金supported by the National Natural Science Foundation of China(Nos.12372066,U23B6009,52171261)the Aeronautical Science Fund(No.20240013052002)the Qing Lan Project。
文摘The structural dynamic response reconstruction technology can extract unmeasured information from limited measured data,significantly impacting vibration control,load identification,parameter identification,fault diagnosis,and related fields.This paper proposes a dynamic response reconstruction method based on the Kalman filter,which simultaneously identifies external excitation and reconstructs dynamic responses at unmeasured positions.The weighted least squares method determines the load weighting matrix for excitation identification,while the minimum variance unbiased estimation determines the Kalman filter gain.The excitation prediction Kalman filter is constructed through time,excitation,and measurement updates.Subsequently,the response at the target point is reconstructed using the state vector,observation matrix,and excitation influence matrix obtained through the excitation prediction Kalman filter algorithm.An algorithm for reconstructing responses in continuous system using the excitation prediction Kalman filtering algorithm in modal space is derived.The proposed structural dynamic response reconstruction method evaluates the response reconstruction and the load identification performance under various load types and errors through simulation examples.Results demonstrate the accurate excitation identification under different load conditions and simultaneous reconstruction of target point responses,verifying the feasibility and reliability of the proposed method.
基金supported by the National Natural Science Foundations of China(Nos.12272411 and 42007259)the State Key Laboratory for GeoMechanics and Deep Underground Engineering,the China University of Mining&Technology(No.SKLGDUEK2207)the Department of Science and Technology of Shaanxi Province(Nos.2022KXJ-107 and 2022JC-LHJJ-16).
文摘Underground engineering in extreme environments necessitates understanding rock mechanical behavior under coupled high-temperature and dynamic loading conditions.This study presents an innovative multi-scale cross-platform PFC-FDEM coupling methodology that bridges microscopic thermal damage mechanisms with macroscopic dynamic fracture responses.The breakthrough coupling framework introduces:(1)bidirectional information transfer protocols enabling seamless integration between PFC’s particle-scale thermal damage characterization and FDEM’s continuum-scale fracture propagation,(2)multi-physics mapping algorithms that preserve crack network geometric invariants during scale transitions,and(3)cross-platform cohesive zone implementations for accurate SHTB dynamic loading simulation.The coupled approach reveals distinct three-stage crack evolution characteristics with temperature-dependent density following an exponential model.High-temperature exposure significantly reduces dynamic strength ratio(60%at 800℃)and diminishes strain-rate sensitivity,with dynamic increase factor decreasing from 1.0 to 2.2(25℃)to 1.0-1.3(800℃).Critically,the coupling methodology captures fundamental energy redistribution mechanisms:thermal crack networks alter elastic energy proportion from 75%to 35%while increasing fracture energy from 5%to 30%.Numerical predictions demonstrate excellent experimental agreement(±8%peak stress-strain errors),validating the PFC-FDEM coupling accuracy.This integrated framework provides essential computational tools for predicting complex thermal-mechanical rock behavior in underground engineering applications.
基金Supported by Finance Science and Technology Project of Hainan Province under Grant No.ZDKJ2021027the National Natural Science Foundation of China under Grant No.52231012.
文摘The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.
基金National Natural Science Foundation of China under Grant Nos.52078205 and 42172322Joint Fund for High-Speed Railway Basic Research under Grant No.U2268213the Postgraduate Scientific Research Innovation Project of Hunan Province under Grant Nos.QL20230104 and CX20240431。
文摘Foamed concrete is widely employed in highway transition sections,due to its lightweight,high-strength,and effective settlement control.It is crucial to investigate its dynamic response linked to the traffic-loading influence zone of embankment and transition section smoothness.In this study,in-situ truck tests were conducted in the road-culvert-bridge transition section to obtain the spatio-temporal response patterns.Based on the vertical response,the influence zone was ascertained.Depending on the longitudinal response,the smoothness was evaluated by equivalent dynamic stiffness(EDS)and acceleration variation rate(AVR).Furthermore,the response discrepancies of embankments with different fillings were compared.Findings reveal exponential attenuation of dynamic stress and acceleration with increasing depth.The acceleration and dynamic displacement exhibit U-shaped patterns in the culvert subsection and abrupt changes in the bridgehead subsection.The influence zone determined by the acceleration attenuation coefficient method,dynamic stress attenuation method,and stress diffusion angle method was 1.55 m,2.05 m,and 2.89 m,respectively.The maximum disparity in EDS occurs at the culvert subsection and bridge abutment,and the AVR ranges from 0 to 0.52 s^(-2).Moreover,94.1%attenuation of the dynamic stress occurred within the 1.5-meter foamed concrete embankment under the setting of 100 kN-60 km/h.
文摘Low collateral damage weapons achieve controlled personnel injury through the coupling of shock waves and particle swarms,where the particle swarms arise from the high-explosive dispersion of compacted metal particle ring.To investigate the dynamic response of the human target under combined shock waves and particle swarms loading,a physical human surrogate torso model(HSTM)was developed,and the dynamic response test experiment was conducted under the combined loading.The effects of particle size on the loading parameters,the damage patterns of the ballistic plate and HSTM,and the dynamic response parameters of the HSTM with and without protection are mainly analyzed.Our findings revealed that particle swarms can effectively delay the shock wave attenuation,especially the best effect when the particle size was 0.28–0.45 mm.The ballistic plate mainly exhibited dense perforation of the outer fabric and impacted crater damage of ceramic plates,whereas the unprotected HSTM was mainly dominated by high-density and small-size ballistic cavity group damage.The peak values of the dynamic response parameters for the HSTM under combined loading were significantly larger than those under bare charge loading,with multiple peaks observed.Under unprotected conditions,the peak acceleration of skeletons and peak pressure of organs increased with the particle size.Under protected conditions,the particle size,the number of particles hit,and the fit of the ballistic plate to the HSTM together affected the dynamic response parameters of the HSTM.
基金the National Natural Science Foundation of China(Grant Nos.52371342,52271338,52101378 and 51979277)。
文摘This study designs four types of liquid-filled cylindrical shell structures to investigate their protection characteristics against explosive shock waves and high-speed fragments.Bare charge and charge-driven prefabricated fragments are employed to examine the damage under blast shock waves and combined blast and fragments loading on various liquid-filled cylindrical shell structures.The test results are compared to numerical calculations and theoretical analysis for the structure's deformation,the liquid medium's movement,and the pressure waves'propagation characteristics under different liquid-filling methods.The results showed that the filling method influences the blast protection and the struc-ture's energy absorption performance.The external filling method reduces the structural deformation,and the internal filling method increases the damage effect.The gapped internal filling method improves the structure's energy absorption efficiency.The pressure wave loading on the liquid-filled cylindrical shell structure differs depending on filling methods.Explosive shock waves and high-speed fragments show a damage enhancement effect on the liquid-filled cylindrical shell structure,depending on the thickness of the internal liquid container layer.The specific impulse on the inner surface of the cylindrical shell positively correlates to the radial deformation of the cylindrical shell structure,and the external liquid layer limits the radial structural deformation.
基金support from the National Natural Science Foundation of China(Nos.51504247,52174092,51904290,and 52074259)the Natural Science Foundation of Jiangsu Province,China(No.BK20220157)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.2022YCPY0202)the China University of Mining and Technology(CUMT)Open Sharing Fund for Large-scale Instruments and Equipment(No.DYGX-2025-47)is gratefully acknowledged.
文摘Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to the concealment nature of interfacial interactions.This study establishes an equivalent shear model for a bolt-resin-rock anchoring system and conducts direct shear tests under dynamic normal load(DNL)boundary from both laboratory experiments and discrete element method(DEM)simulations.The research investigates the influence of normal dynamic load amplitude(An)and rock type on shear strength parameters,elucidating the evolutionary characteristics and underlying mechanisms of shear load and normal displacement fluctuations induced by cyclic normal loading,with maximum shear load decreasing by 36.81%to 46.94%as An increases from 10%to 70%when rock type varies from coal to limestone.Through analysis of strain field evolution,the critical impact of rock type on localization of shear failure surface is revealed,with systematic summarization of differentiated wear characteristics,failure modes,and key controlling factors associated with shear failure surface.Mesoscopic investigations enabled by DEM simulations uncover the nonuniform distribution of contact force chains within the material matrix and across the anisotropic interfaces under various DNL boundaries,clarify rock type dependent crack propagation pathways,and quantitatively assess the damage extent of shear failure surface,with the anisotropic interface damage factor increasing from 34.9%to 56.6%as An rises from 10%to 70%,and decreasing from 49.6%to 23.4%as rock type varies from coal to limestone.
基金Project(52108361)supported by the National Natural Science Foundation of ChinaProjects(BK20231217,BK20220265)supported by the Basic Research Program of Jiangsu Province,China+5 种基金Project(sklhse-KF-2025-D-02)supported by the Open Research Fund Program of the State Key Laboratory of Hydroscience and Engineering,ChinaProject(2023ZB15)supported by the Independent Research Project of the State Key Laboratory of Subtropical Building and Urban Science,ChinaProject(SKLGME023001)supported by the Key Laboratory of Geomechanics and Geotechnical Engineering Safety,the Chinese Academy of SciencesProject(2025A04J3992)supported by the Basic and Applied Basic Research Project of the Guangzhou Science and Technology Bureau,ChinaProject(SKLGP2022Z015)supported by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project,ChinaProjects(2023YFS0436,2024NSFSC1715)supported by the Science and Technology Department of Sichuan Province,China。
文摘Steep bedding slopes are widely distributed in Southwestern China’s mountainous regions and have complex seismic responses and instability risks,causing casualties and property losses.Considering the high-seismic-intensity environment,the dynamic failure evolution and instability mechanism of high-steep bedding slopes are simulated via the discrete element method and shaking table test.The dynamic response characteristics and cumulative failure effects of slopes subjected to continuous ground motion are investigated.The results show that the dynamic response characteristics of slopes under continuous earthquakes are influenced by geological and topographic conditions.Elevation has a distinct impact on both the slope interior and surface,with amplification effects more pronounced on the surface.The weak interlayers have different influences on the dynamic amplification effect of slopes.Weak interlayers have dynamic magnification effects on the slope surface at relative elevations of 0-0.33 and 0.82-1.0 but have weakening effects between 0.33 and 0.82.Moreover,the weak interlayers also have controlling effects on the dynamic instability mode of slopes.The characteristics of intergranular contact failure,fracture propagation,and displacement distribution are analyzed to reveal the dynamic failure evolution and instability mechanism through the discrete-element model.The dynamic instability process of slopes includes three stages:fracture initiation(0-0.2g),fracture expansion(0.2g-0.3g),and sliding instability(0.3g-0.6g).This work can provide a valuable reference for the seismic stability and reinforcement of complex slopes.
基金supported by National Natural Science Foundation of China(Nos.92263109 and 61904188)the Shanghai Rising-Star Program(No.22QA1410400)。
文摘Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density functional theory(DFT)calculations,researchers can investigate gas sensing mechanisms,optimize,and predict the electronic structures and response characteristics of these materials,and thereby identify candidate materials with promising gas sensing applications for targeted design.This review concentrates on three primary applications of DFT technology in the realm of organic semiconductor-based gas sensors:(1)Investigating the sensing mechanisms by analyzing the interactions between gas molecules and sensing materials through DFT,(2)simulating the dynamic responses of gas molecules,which involves the behavior on the sensing interface using DFT combined with other computational methods to explore adsorption and diffusion processes,and(3)exploring and designing sensitive materials by employing DFT for screening and predicting chemical structures,thereby developing new sensing materials with exceptional performance.Furthermore,this review examines current research outcomes and anticipates the extensive application prospects of DFT technology in the domain of organic semiconductor-based gas sensors.These efforts are expected to provide valuable insights for further indepth exploration of DFT applications in sensor technology,thereby fostering significant advancements and innovations in the field.
基金the National Natural Science Foundation of China(No.32260235)。
文摘The dynamic response characteristics of scoliosis and kyphosis to vibration are currently unclear.The finite element method(FEM)was employed to study the vibration response of patients with idiopathic scoliosis and kyphosis.The objective is to analyze the dynamic characteristics of idiopathic scoliosis and kyphosis using FEM.The finite element model of T1—S1 segments was established and verified using the CT scanning images.The established scoliosis and kyphosis models were verified statistically and dynamically.The finite element software Abaqus was utilized to analyze the mode,harmonic response,and transient dynamics of scoliosis and kyphosis.The first four natural frequencies extracted from modal analysis were 1.34,2.26,4.49 and 17.69 Hz respectively.Notably,the first three natural frequencies decreased with the increase of upper body mass.In harmonic response analysis,the frequency corresponding to the maximum amplitude in x direction was the first order natural frequency,and the frequency corresponding to the maximum amplitude in y and z directions was the second order natural frequency.At the same resonance frequency,the amplitude of the thoracic spine was larger relative to that of the lumbar spine.The time domain results of transient analysis showed that the displacement dynamic response of each segment presented cyclic response characteristics over time.Under 2.26 Hz excitation,the dynamic response of the research object appeared as resonance.The higher the degree of spinal deformity,the greater the fundamental frequency.The first three natural modes of scoliosis and kyphosis contain vibration components in the vertical direction.The second order natural frequency was the most harmful to patients with scoliosis and kyphosis.Under cyclic loading,the deformation of the thoracic cone exceeds that of the lumbar cone.
文摘This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes the most representative models and methods of analysis in the existing literature and illustrates all of them by numerical examples.Thus,13 such examples are presented here in some detail.Both flexible and rigid(concrete)pavement models involving simple and elaborate cases with respect to geometry and material behavior are considered.Thus,homogeneous or layered half-spaces with isotropic or cross-anisotropic and elastic,viscoelastic or poroelastic properties are considered.The vehicles are modeled as simple point or distributed loads or discrete spring-mass-dashpot system moving with constant or variable velocity.The dynamic response of the above pavement-vehicle systems is obtained by analytical/numerical or purely numerical methods of solution.Analytical/numerical methods have mainly to do with Fourier transforms or complex Fourier series with respect to both space and time.Purely numerical methods involve the finite element method(FEM)and the boundary element method(BEM)working in time or frequency domain.Critical discussions on the advantages and disadvantages of the various pavement-vehicle models and their methods of analysis are provided and the effects of the main parameters on the pavement response are determined through parametric studies and presented in the examples.Finally,conclusions are provided and suggestions for future research are made.
基金supported by the National Natural Science Foundation of China(No.52177134)。
文摘In the aerospace sector,the soft magnetic materials of Hermetically Sealed Electromagnetic Relays(HSERs)are critical in forming magnetic circuits.Conventional soft magnetic materials,primarily magnetic iron,have been unable to meet the development trend of fast-response,miniaturized,and lightweight aerospace and aviation systems.This paper applies circuit theory and electromagnetics theory to establish a Field-Circuit Coupling Mathematical Model(FCCMM)for dynamic response analysis of HSERs.This model centers on inductance calculation,with the core's permeability and saturation magnetic flux density as critical parameters.Based on this model,for a specific type of HSER,this paper introduced three alloys with key parameters different from magnetic iron,then tested the magnetic characteristic curves of these four soft magnetic materials,followed by simulations to obtain the electromagnetic characteristics of digital mock-ups corresponding to these four materials,compared and validated the dynamic responses corresponding to these four soft magnetic materials finally.Based on the theoretical model analysis results,this paper designed a lightweight coil to minimize response time,made prototypes,set up test systems,and tested dynamic characteristics.The experimental results indicate that the nanocrystalline alloy1K107B exhibits the most significant optimization,reducing the closing time by 40.48%and achieving a weight reduction of 6.53%.
