In this paper, a nonlinear mathematical model for analyzing dynamical response to the large deformation of piles with initial displacements is firstly established with the arc-coordinate, and it is a set of nonlinear ...In this paper, a nonlinear mathematical model for analyzing dynamical response to the large deformation of piles with initial displacements is firstly established with the arc-coordinate, and it is a set of nonlinear integral-differential equa- tions, in which, the Winkeler model is used to simulate the resistance of the soil to the pile. Secondly, a set of new auxiliary functions are introduced. The differential-integral equations are transformed into a set of nonlinear differential equations, and the differential quadrature method （DQM） and the finite difference method （FDM） are applied to discretize the set of nonlinear equations in the spatial and time domains, respectively. Then, the Newton-Raphson method is used to solve the set of discretization algebraic equations at each time step. Finally, numerical examples are presented, and the dynamical re- sponses to the deformation of piles, including configuration, bending moment and shear force, are graphically illuminated. In calculation, two types of initial displacements and dynamical loads are applied, and the effects of parameters on the dynamical responses of piles are analyzed in detail.展开更多
In this paper, the necessary theoretical analysis for the approximation boundary element method to solve dynamical response of viscoelastic thin plate presented in [1] is.discussed. The theorem of existence and uniq...In this paper, the necessary theoretical analysis for the approximation boundary element method to solve dynamical response of viscoelastic thin plate presented in [1] is.discussed. The theorem of existence and uniqueness of the approximate solution andthe error estimation are also obtained. Based on these conclusions , the principle forchoosing the mesh size and the number of truncated terms in the fundamental solution are given. It isshown that the theoretical ana analysis in this paper are consistent with thenumerical results in [1].展开更多
In this paper, a boundary element method for solving dynamical response of viscoelastic thin plate is given. In Laplace domain, we propose two methods to approximate the fundamental solution and develop the correspond...In this paper, a boundary element method for solving dynamical response of viscoelastic thin plate is given. In Laplace domain, we propose two methods to approximate the fundamental solution and develop the corresponding boundary element method. Then using the improved Bellman's numerical inversion of the Laplace transform, the solution of the original problem is obtained. The numerical results show that this method has higher accuracy and faster convergence.展开更多
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
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
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
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
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
Amid increasingly frequent military conflicts and explosion events,accurately predicting the dynamic response of reinforced concrete(RC) slabs,key load-bearing components in building structures,is essential for unders...Amid increasingly frequent military conflicts and explosion events,accurately predicting the dynamic response of reinforced concrete(RC) slabs,key load-bearing components in building structures,is essential for understanding blast-induced damage and enhancing structural protection.However,current approaches predominantly rely on experimental tests,finite element(FE) simulations,and conventional machine learning(ML) techniques,which are o ften costly,inefficie nt,narrowly applicable,and insufficiently accurate.To overcome these challenges,this study aims to optimize ML models,refine architectural designs,and improve model interpretability.A comprehensive dataset comprising 489 samples was constructed by integrating experimental and simulation data from existing literature,incorporating 15 input features and one target variable.Based on this dataset,a novel method,termed MOPSO-TXGBoost,was proposed.Building on XGBoost as a baseline,the method employs multiobjective particle swarm optimization(MOPSO) for hyperparameter tuning,introduces a tri-stream stacking architecture to enhance feature representation,and trains three distinct models to improve generalization performance.A weighted fusion strategy is employed to further enhance the accuracy of predictio n.Additio nally,a model comprehensive evaluation(MCE) index is introduced,which integrates error metrics and fitting performance to facilitate systematic model assessment.Experimental results indicate that,compared with the baseline XGBoost model,the proposed approach reduces prediction error by 61.4% and increases the coefficient of determination(R^(2)) by 0.217.Moreover,it outperforms several mainstream machine learning(ML) algorithms.The findings of this study advance ML-based blast damage prediction and provide theoretical support for safety assessment and protection optimization of RC slab structures.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
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
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
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
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
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
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
A rising water table increases soil water content,reduces soil strength,and amplifies vibrations under identical train loads,thereby posing greater risks to train operations.To investigate this phenomenon,we used a 2....A rising water table increases soil water content,reduces soil strength,and amplifies vibrations under identical train loads,thereby posing greater risks to train operations.To investigate this phenomenon,we used a 2.5D finite element(FE)model of a coupled vehicle–embankment–ground system based on Biot’s theory.The ground properties were derived from a typical soil profile of the Yangtze River basin,using geological data from Shanghai,China.The findings indicate that a rise in the water table leads to increased dynamic displacements of both the track and the ground.This amplification effect extends beyond the depth of the water table,impacting the entire embankment–foundation cross-section,and intensifies with higher train speeds.However,the water table rise has a limited impact on the critical speed of trains and dominant frequency contents.The dynamic response of the embankment is more significantly affected by water table rises within the subgrade than by those within the ground.When the water table rises into the subgrade,significant excess pore pressure is generated inside the embankment,causing a substantial drop in effective stress.As a result,the stress path of the soil elements in the subgrade approaches the Mohr-Coulomb failure line,increasing the likelihood of soil failure.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
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
基金supported by the National Natural Science Foundation of China (Grant No.50278051)Shanghai Pujiang Program(Grant No.07pj14073)
文摘In this paper, a nonlinear mathematical model for analyzing dynamical response to the large deformation of piles with initial displacements is firstly established with the arc-coordinate, and it is a set of nonlinear integral-differential equa- tions, in which, the Winkeler model is used to simulate the resistance of the soil to the pile. Secondly, a set of new auxiliary functions are introduced. The differential-integral equations are transformed into a set of nonlinear differential equations, and the differential quadrature method （DQM） and the finite difference method （FDM） are applied to discretize the set of nonlinear equations in the spatial and time domains, respectively. Then, the Newton-Raphson method is used to solve the set of discretization algebraic equations at each time step. Finally, numerical examples are presented, and the dynamical re- sponses to the deformation of piles, including configuration, bending moment and shear force, are graphically illuminated. In calculation, two types of initial displacements and dynamical loads are applied, and the effects of parameters on the dynamical responses of piles are analyzed in detail.
文摘In this paper, the necessary theoretical analysis for the approximation boundary element method to solve dynamical response of viscoelastic thin plate presented in [1] is.discussed. The theorem of existence and uniqueness of the approximate solution andthe error estimation are also obtained. Based on these conclusions , the principle forchoosing the mesh size and the number of truncated terms in the fundamental solution are given. It isshown that the theoretical ana analysis in this paper are consistent with thenumerical results in [1].
文摘In this paper, a boundary element method for solving dynamical response of viscoelastic thin plate is given. In Laplace domain, we propose two methods to approximate the fundamental solution and develop the corresponding boundary element method. Then using the improved Bellman's numerical inversion of the Laplace transform, the solution of the original problem is obtained. The numerical results show that this method has higher accuracy and faster convergence.
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.
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 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.
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.
文摘Amid increasingly frequent military conflicts and explosion events,accurately predicting the dynamic response of reinforced concrete(RC) slabs,key load-bearing components in building structures,is essential for understanding blast-induced damage and enhancing structural protection.However,current approaches predominantly rely on experimental tests,finite element(FE) simulations,and conventional machine learning(ML) techniques,which are o ften costly,inefficie nt,narrowly applicable,and insufficiently accurate.To overcome these challenges,this study aims to optimize ML models,refine architectural designs,and improve model interpretability.A comprehensive dataset comprising 489 samples was constructed by integrating experimental and simulation data from existing literature,incorporating 15 input features and one target variable.Based on this dataset,a novel method,termed MOPSO-TXGBoost,was proposed.Building on XGBoost as a baseline,the method employs multiobjective particle swarm optimization(MOPSO) for hyperparameter tuning,introduces a tri-stream stacking architecture to enhance feature representation,and trains three distinct models to improve generalization performance.A weighted fusion strategy is employed to further enhance the accuracy of predictio n.Additio nally,a model comprehensive evaluation(MCE) index is introduced,which integrates error metrics and fitting performance to facilitate systematic model assessment.Experimental results indicate that,compared with the baseline XGBoost model,the proposed approach reduces prediction error by 61.4% and increases the coefficient of determination(R^(2)) by 0.217.Moreover,it outperforms several mainstream machine learning(ML) algorithms.The findings of this study advance ML-based blast damage prediction and provide theoretical support for safety assessment and protection optimization of RC slab structures.
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(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%.
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.
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 Key Research and Development Program Young Scientist Project(No.2024YFC2911000)the National Natural Science Foundation of China(No.52108308).
文摘A rising water table increases soil water content,reduces soil strength,and amplifies vibrations under identical train loads,thereby posing greater risks to train operations.To investigate this phenomenon,we used a 2.5D finite element(FE)model of a coupled vehicle–embankment–ground system based on Biot’s theory.The ground properties were derived from a typical soil profile of the Yangtze River basin,using geological data from Shanghai,China.The findings indicate that a rise in the water table leads to increased dynamic displacements of both the track and the ground.This amplification effect extends beyond the depth of the water table,impacting the entire embankment–foundation cross-section,and intensifies with higher train speeds.However,the water table rise has a limited impact on the critical speed of trains and dominant frequency contents.The dynamic response of the embankment is more significantly affected by water table rises within the subgrade than by those within the ground.When the water table rises into the subgrade,significant excess pore pressure is generated inside the embankment,causing a substantial drop in effective stress.As a result,the stress path of the soil elements in the subgrade approaches the Mohr-Coulomb failure line,increasing the likelihood of soil failure.
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.
