In dealing with abrasive waterjet machining（AWJM） simulation,most literatures apply finite element method（FEM） to build pure waterjet models or single abrasive particle erosion models.To overcome the mesh distorti...In dealing with abrasive waterjet machining（AWJM） simulation,most literatures apply finite element method（FEM） to build pure waterjet models or single abrasive particle erosion models.To overcome the mesh distortion caused by large deformation using FEM and to consider the effects of both water and abrasive,the smoothed particle hydrodynamics（SPH） coupled FEM modeling for AWJM simulation is presented,in which the abrasive waterjet is modeled by SPH particles and the target material is modeled by FEM.The two parts interact through contact algorithm.Utilizing this model,abrasive waterjet with high velocity penetrating the target materials is simulated and the mechanism of erosion is depicted.The relationships between the depth of penetration and jet parameters,including water pressure and traverse speed,etc,are analyzed based on the simulation.The simulation results agree well with the existed experimental data.The mixing multi-materials SPH particles,which contain abrasive and water,are adopted by means of the randomized algorithm and material model for the abrasive is presented.The study will not only provide a new powerful tool for the simulation of abrasive waterjet machining,but also be beneficial to understand its cutting mechanism and optimize the operating parameters.展开更多
With regard to blasting in deep rock masses,it is commonly thought that an increase in the in-situ stress will change the blast-induced rock crack propagation and ultimately affect rock fragmentation.However,little at...With regard to blasting in deep rock masses,it is commonly thought that an increase in the in-situ stress will change the blast-induced rock crack propagation and ultimately affect rock fragmentation.However,little attention has been given to the change in seismic wave radiation when the fractured zone changes with the in-situ stress.In this study,the influences of in-situ stress on blast-induced rock fracture and seismic wave radiation are numerically investigated by a coupled SPH-FEM simulation method.The results show that the change in blast-induced rock fracture with in-situ stress has a considerable effect on the seismic wave energy and composition.As the in-situ stress level increases,the size of the fractured zone is significantly reduced,and more explosion energy is transformed into seismic energy.A reduction in the size of the fractured zone(seismic wave source zone)results in a higher frequency content of the seismic waves.In a nonhydrostatic in-situ stress field,blast-induced cracks are most suppressed in the direction of the minimum in-situ stress,and thus the seismic waves generated in this direction have the highest energy density.In addition to P-waves,Swaves are also generated when a circular explosive is detonated in a nonhydrostatic in-situ stress field.The S-waves result from the asymmetrical release of rock strain energy due to the anisotropic blast-induced fracture pattern.展开更多
为研究高压水射流破除钢筋混凝土力学机制,本文基于SPH(Smooth Particle Hydrodynamics)-FEM(Finite Element Method)耦合算法方法建立了高压水射流冲击钢筋混凝土数值模型。研究表明:液固初始接触时,水锤效应导致液固接触边界出现断裂...为研究高压水射流破除钢筋混凝土力学机制,本文基于SPH(Smooth Particle Hydrodynamics)-FEM(Finite Element Method)耦合算法方法建立了高压水射流冲击钢筋混凝土数值模型。研究表明:液固初始接触时,水锤效应导致液固接触边界出现断裂,剪应力促使裂纹向射流轴向演化。冲击过程中,首先受拉钢筋上部靠边缘侧混凝土拉伸失效,其次混凝土内部产生条状交叉裂纹,然后箍筋、受拉钢筋与混凝土的上连接处混凝土出现损伤,最后箍筋、受拉钢筋与混凝土的下连接处混凝土出现损伤。整个过程中,轴线处钢筋拉伸应力几乎为0,失效混凝土下部的钢筋所受拉伸应力增大到峰值后不断减小并趋于0。研究结果对于高压水射流破除钢筋混凝土可提供理论支撑。展开更多
A coupled numerical calculation method combining smooth particle hydrodynamics(SPH)and the finite element method(FEM)was implemented to investigate the seismic response of horizontal storage tanks.Anumericalmodel of a...A coupled numerical calculation method combining smooth particle hydrodynamics(SPH)and the finite element method(FEM)was implemented to investigate the seismic response of horizontal storage tanks.Anumericalmodel of a horizontal storage tank featuring a free liquid surface under seismic action was constructed using the SPH–FEM coupling method.The stored liquid was discretized using SPH particles,while the tank and supports were discretized using the FEM.The interaction between the stored liquid and the tank was simulated by using the meshless particle contact method.Then,the numerical simulation results were compared and analyzed against seismic simulation shaking table test data to validate the method.Subsequently,a series of numerical models,considering different liquid storage volumes and seismic effects,were constructed to obtain time history data of base shear and top center displacement,which revealed the seismic performance of horizontal storage tanks.Numerical simulation results and experimental data showed good agreement,with an error rate of less than 18.85%.And this conformity signifies the rationality of the SPH-FEM coupling method.The base shear and top center displacement values obtained by the coupled SPH-FEM method were only 53.3% to 69.1% of those calculated by the equivalent mass method employed in the current code.As the stored liquid volume increased,the seismic response of the horizontal storage tank exhibited a gradual upward trend,with the seismic response increasing from 73% to 388% for every 35% increase in stored liquid volume.The maximum von Mises stress of the tank and the supports remained below the steel yield strength during the earthquake.The coupled SPH-FEM method holds certain advantages in studying the seismic problems of tanks with complex structural forms,particularly due to the representation of the flow field distribution during earthquakes by involving reservoir fluid participation.展开更多
基金supported by Shandong Provincial Natural Science Foundation of China (Grant No. Y2007A07)
文摘In dealing with abrasive waterjet machining（AWJM） simulation,most literatures apply finite element method（FEM） to build pure waterjet models or single abrasive particle erosion models.To overcome the mesh distortion caused by large deformation using FEM and to consider the effects of both water and abrasive,the smoothed particle hydrodynamics（SPH） coupled FEM modeling for AWJM simulation is presented,in which the abrasive waterjet is modeled by SPH particles and the target material is modeled by FEM.The two parts interact through contact algorithm.Utilizing this model,abrasive waterjet with high velocity penetrating the target materials is simulated and the mechanism of erosion is depicted.The relationships between the depth of penetration and jet parameters,including water pressure and traverse speed,etc,are analyzed based on the simulation.The simulation results agree well with the existed experimental data.The mixing multi-materials SPH particles,which contain abrasive and water,are adopted by means of the randomized algorithm and material model for the abrasive is presented.The study will not only provide a new powerful tool for the simulation of abrasive waterjet machining,but also be beneficial to understand its cutting mechanism and optimize the operating parameters.
基金Projects(51969015,U1765207)supported by the National Natural Science Foundation of ChinaProjects(20192ACB21019,20181BAB206047)supported by the Natural Science Foundation of Jiangxi Province,China。
文摘With regard to blasting in deep rock masses,it is commonly thought that an increase in the in-situ stress will change the blast-induced rock crack propagation and ultimately affect rock fragmentation.However,little attention has been given to the change in seismic wave radiation when the fractured zone changes with the in-situ stress.In this study,the influences of in-situ stress on blast-induced rock fracture and seismic wave radiation are numerically investigated by a coupled SPH-FEM simulation method.The results show that the change in blast-induced rock fracture with in-situ stress has a considerable effect on the seismic wave energy and composition.As the in-situ stress level increases,the size of the fractured zone is significantly reduced,and more explosion energy is transformed into seismic energy.A reduction in the size of the fractured zone(seismic wave source zone)results in a higher frequency content of the seismic waves.In a nonhydrostatic in-situ stress field,blast-induced cracks are most suppressed in the direction of the minimum in-situ stress,and thus the seismic waves generated in this direction have the highest energy density.In addition to P-waves,Swaves are also generated when a circular explosive is detonated in a nonhydrostatic in-situ stress field.The S-waves result from the asymmetrical release of rock strain energy due to the anisotropic blast-induced fracture pattern.
文摘为研究高压水射流破除钢筋混凝土力学机制,本文基于SPH(Smooth Particle Hydrodynamics)-FEM(Finite Element Method)耦合算法方法建立了高压水射流冲击钢筋混凝土数值模型。研究表明:液固初始接触时,水锤效应导致液固接触边界出现断裂,剪应力促使裂纹向射流轴向演化。冲击过程中,首先受拉钢筋上部靠边缘侧混凝土拉伸失效,其次混凝土内部产生条状交叉裂纹,然后箍筋、受拉钢筋与混凝土的上连接处混凝土出现损伤,最后箍筋、受拉钢筋与混凝土的下连接处混凝土出现损伤。整个过程中,轴线处钢筋拉伸应力几乎为0,失效混凝土下部的钢筋所受拉伸应力增大到峰值后不断减小并趋于0。研究结果对于高压水射流破除钢筋混凝土可提供理论支撑。
基金supported by Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration(Grant Nos.2021B06,2021C05)Heilongjiang Natural Science Foundation Joint Guidance Project(Grant No.LH2021E122).
文摘A coupled numerical calculation method combining smooth particle hydrodynamics(SPH)and the finite element method(FEM)was implemented to investigate the seismic response of horizontal storage tanks.Anumericalmodel of a horizontal storage tank featuring a free liquid surface under seismic action was constructed using the SPH–FEM coupling method.The stored liquid was discretized using SPH particles,while the tank and supports were discretized using the FEM.The interaction between the stored liquid and the tank was simulated by using the meshless particle contact method.Then,the numerical simulation results were compared and analyzed against seismic simulation shaking table test data to validate the method.Subsequently,a series of numerical models,considering different liquid storage volumes and seismic effects,were constructed to obtain time history data of base shear and top center displacement,which revealed the seismic performance of horizontal storage tanks.Numerical simulation results and experimental data showed good agreement,with an error rate of less than 18.85%.And this conformity signifies the rationality of the SPH-FEM coupling method.The base shear and top center displacement values obtained by the coupled SPH-FEM method were only 53.3% to 69.1% of those calculated by the equivalent mass method employed in the current code.As the stored liquid volume increased,the seismic response of the horizontal storage tank exhibited a gradual upward trend,with the seismic response increasing from 73% to 388% for every 35% increase in stored liquid volume.The maximum von Mises stress of the tank and the supports remained below the steel yield strength during the earthquake.The coupled SPH-FEM method holds certain advantages in studying the seismic problems of tanks with complex structural forms,particularly due to the representation of the flow field distribution during earthquakes by involving reservoir fluid participation.
文摘高拱坝由于具有拱梁受力特性,其坝身往往较薄,而当薄拱坝坝后遭受侵彻爆炸打击时,高拱坝的安全将面临严峻的威胁。采用声固耦合方法模拟库水与大坝-地基动态耦合作用,光滑粒子流体动力学-有限元耦合方法(smoothed particle hydrodynamics-finite element method,SPH-FEM)模拟侵彻内部爆炸及大坝毁伤发展过程,建立了考虑混凝土高应变率效应的库水-坝体-爆炸耦合作用模型,研究了薄拱坝坝后遭受侵彻内部爆炸打击后的毁伤发展过程,探讨了坝后侵彻深度对薄拱坝坝身内部爆炸毁伤特性的影响,揭示了双曲拱坝上、下游几何特征对坝身侵彻爆炸破坏发展过程和毁伤机理。结果表明:高拱坝上、下游面的几何特征对大坝内部爆炸毁伤发展过程具有重要的影响;薄拱坝坝身遭受侵彻爆炸将对大坝安全构成严重威胁,且侵彻高拱坝中部破坏效应最大。
