In this study,a powerful thermo-hydro-mechanical(THM)coupling solution scheme for saturated poroelastic media involving brittle fracturing is developed.Under the local thermal non-equilibrium(LTNE)assumption,this sche...In this study,a powerful thermo-hydro-mechanical(THM)coupling solution scheme for saturated poroelastic media involving brittle fracturing is developed.Under the local thermal non-equilibrium(LTNE)assumption,this scheme seamlessly combines the material point method(MPM)for accurately tracking solid-phase deformation and heat transport,and the Eulerian finite element method(FEM)for effectively capturing fluid flow and heat advection-diffusion behavior.The proposed approach circumvents the substantial challenges posed by large nonlinear equation systems with the monolithic solution scheme.The staggered solution process strategically separates each physical field through explicit or implicit integration.The characteristic-based method is used to stabilize advection-dominated heat flows for efficient numerical implementation.Furthermore,a fractional step approach is employed to decompose fluid velocity and pressure,thereby suppressing pore pressure oscillation on the linear background grid.The fracturing initiation and propagation are simulated by a rate-dependent phase field model.Through a series of quasi-static and transient simulations,the exceptional performance and promising potential of the proposed model in addressing THM fracturing problems in poro-elastic media is demonstrated.展开更多
In a bird strike, the bird undergoes large deformation like flows; while most part of the structure is in small deformation, the region near the impact point may experience large deformations, even fail. This paper de...In a bird strike, the bird undergoes large deformation like flows; while most part of the structure is in small deformation, the region near the impact point may experience large deformations, even fail. This paper develops a coupled shell-material point method （CSMPM） for bird strike simulation, in which the bird is modeled by the material point method （MPM） and the aircraft structure is modeled by the Belytschko-Lin-Tsay shell element. The interaction between the bird and the structure is handled by a particle-to-surface contact algorithm. The distorted and failed shell elements will be eroded if a certain criterion is reached. The proposed CSMPM takes full advantages of both the finite element method and the MPM for bird strike simulation and is validated by several numerical examples.展开更多
The material point method(MPM)has been gaining increasing popularity as an appropriate approach to the solution of coupled hydro-mechanical problems involving large deformation.In this paper,we survey the current stat...The material point method(MPM)has been gaining increasing popularity as an appropriate approach to the solution of coupled hydro-mechanical problems involving large deformation.In this paper,we survey the current state-of-the-art in the MPM simulation of hydro-mechanical behaviour in two-phase porous geomaterials.The review covers the recent advances and developments in the MPM and their extensions to capture the coupled hydro-mechanical problems involving large deformations.The focus of this review is aiming at providing a clear picture of what has or has not been developed or implemented for simulating two-phase coupled large deformation problems,which will provide some direct reference for both practitioners and researchers.展开更多
This paper proposed the explicit generalized-a time scheme and periodic boundary conditions in the material point method(MPM)for the simulation of coseismic site response.The proposed boundary condition uses an intuit...This paper proposed the explicit generalized-a time scheme and periodic boundary conditions in the material point method(MPM)for the simulation of coseismic site response.The proposed boundary condition uses an intuitive particle-relocation algorithm ensuring material points always remain within the computational mesh.The explicit generalized-a time scheme was implemented in MPM to enable the damping of spurious high frequency oscillations.Firstly,the MPM was verified against finite element method(FEM).Secondly,ability of the MPM in capturing the analytical transfer function was investigated.Thirdly,a symmetric embankment was adopted to investigate the effects of ground motion arias intensity(I_(a)),geometry dimensions,and constitutive models.The results show that the larger the model size,the higher the crest runout and settlement for the same ground motion.When using a Mohr-Coulomb model,the crest runout increases with increasing I_(a).However,if the strain-softening law is activated,the results are less influenced by the ground motion.Finally,the MPM results were compared with the Newmark sliding block solution.The simplified analysis herein highlights the capabilities of MPM to capture the full deformation process for earthquake engineering applications,the importance of geometry characterization,and the selection of appropriate constitutive models when simulating coseismic site response and subsequent large deformations.展开更多
As a Lagrangian meshless method, the material point method （MPM） is suitable for dynamic problems with extreme deformation, but its efficiency and accuracy are not as good as that of the finite element method （FEM...As a Lagrangian meshless method, the material point method （MPM） is suitable for dynamic problems with extreme deformation, but its efficiency and accuracy are not as good as that of the finite element method （FEM） for small deformation problems. Therefore, an algorithm for the coupling of FEM and MPM is proposed to take advantages of both methods. Furthermore, a conversion scheme of elements to particles is developed. Hence, the material domain is firstly discretized by finite elements, and then the distorted elements are automatically converted into MPM particles to avoid element entanglement. The interaction between finite elements and MPM particles is implemented based on the background grid in MPM framework. Numerical results are in good agreement with that of both FEM and MPM展开更多
随着山区高速公路建设的迅速推进,弃渣场的稳定性及潜在失稳灾害评估日益受到重视。具有巨大能量的滑坡体,可能会冲击破坏沿途的结构物进而威胁生命财产安全。充分发挥利用物质点法(material point method,MPM)可以对连续介质大变形过...随着山区高速公路建设的迅速推进,弃渣场的稳定性及潜在失稳灾害评估日益受到重视。具有巨大能量的滑坡体,可能会冲击破坏沿途的结构物进而威胁生命财产安全。充分发挥利用物质点法(material point method,MPM)可以对连续介质大变形过程模拟和离散元法(digital elevation model,DEM)能够精准的接触判断优势,MPM-DEM耦合算法可有效解决滑坡体与复杂地形、沿线结构物之间的相互作用问题。文章基于GPU并行高性能计算软件CoSim中的MPM-DEM耦合算法,实现了对弃渣场边坡稳定性、潜在失稳灾害的动力学分析。研究首先以散粒体冲击结构物的算例,验证了该算法的合理性与准确性;在此基础上,以云南某高速公路弃渣场为研究案例,进一步计算其稳定性系数,并预测潜在失稳灾害的影响范围与危害程度。结果表明,该弃渣场边坡目前处于稳定状态;若发生失稳,滑坡体将对下游高速公路桥桩产生巨大冲击力。该耦合算法在弃渣场边坡稳定性与失稳灾害动力学分析中具备显著优势,能够实现边坡“稳定性→大变形→流动→堆积”的全过程分析。展开更多
深度积分算法可将滑坡沿地表滑动的三维模型化简为二维模型进行求解,通过减少控制方程未知量的个数以提升求解效率。物质点法(material point method,MPM)具有无网格法和有网格法的双重优势,模拟滑坡大变形问题时可避免网格畸变现象。...深度积分算法可将滑坡沿地表滑动的三维模型化简为二维模型进行求解,通过减少控制方程未知量的个数以提升求解效率。物质点法(material point method,MPM)具有无网格法和有网格法的双重优势,模拟滑坡大变形问题时可避免网格畸变现象。采用深度积分耦合物质点法建立滑坡数值模型,给出算法实现具体流程,基于影响域改进的物质点法(influence domain material point method,IDMPM),针对两个典型无倾角底面光滑和有倾角底面不光滑滑坡算例进行基准测试。在计算精度方面,深度积分耦合物质点法模型能较好地预测远端距离、流速、深度等滑移特征参数;在计算效率方面,与常规物质点法求解格式相比,深度积分耦合物质点法模型可大幅度提高运行效率。该研究成果可为滑坡地质灾害破坏范围的分析预测、危害评估、应急抢险提供有效理论依据和时间保障。展开更多
功能梯度材料是一种特殊的复合材料,在高温下能很好地缓解热应力.由于其材料结构和物理力学性质的特殊性,热冲击下功能梯度梁呈现出较为复杂的热力学行为.B样条物质点法作为一种物质点法的改进算法,已在各类复杂问题中展现了强大的求解...功能梯度材料是一种特殊的复合材料,在高温下能很好地缓解热应力.由于其材料结构和物理力学性质的特殊性,热冲击下功能梯度梁呈现出较为复杂的热力学行为.B样条物质点法作为一种物质点法的改进算法,已在各类复杂问题中展现了强大的求解能力.本文基于傅里叶热传导理论与BSMPM(B-spline Material Point Method)的框架提出了热力耦合方程的离散格式,分析了SiC-Al功能梯度梁的自由振动以及温度荷载作用下的动力响应;同时,基于快速傅里叶变换,研究了SiC-Al功能梯度梁横向振动固有频率随梯度幂律指数的变化规律,并分别与传统物质点法、有限元法和理论解进行了比较分析.结果表明:相较于传统物质点法,B样条物质点法有效改善了应力振荡以及能量耗散.热冲击作用下,B样条物质点法所得功能梯度梁内温度分布与有限元结果吻合较好;B样条物质点法能有效求得一阶横向振动固有频率;随着梯度幂律指数的增加,功能梯度梁固有频率随幂函数变化减小,与理论结果吻合较好.本文验证了热力耦合B样条物质点法的有效性,拓展了B样条物质点法的工程应用,为功能梯度材料在热力耦合作用下的动力响应研究提供了新的计算思路.展开更多
基金supported by National Natural Science Foundation of China(Grant No.42377149)the Research Grants Council of Hong Kong(General Research Fund Project No.17202423).
文摘In this study,a powerful thermo-hydro-mechanical(THM)coupling solution scheme for saturated poroelastic media involving brittle fracturing is developed.Under the local thermal non-equilibrium(LTNE)assumption,this scheme seamlessly combines the material point method(MPM)for accurately tracking solid-phase deformation and heat transport,and the Eulerian finite element method(FEM)for effectively capturing fluid flow and heat advection-diffusion behavior.The proposed approach circumvents the substantial challenges posed by large nonlinear equation systems with the monolithic solution scheme.The staggered solution process strategically separates each physical field through explicit or implicit integration.The characteristic-based method is used to stabilize advection-dominated heat flows for efficient numerical implementation.Furthermore,a fractional step approach is employed to decompose fluid velocity and pressure,thereby suppressing pore pressure oscillation on the linear background grid.The fracturing initiation and propagation are simulated by a rate-dependent phase field model.Through a series of quasi-static and transient simulations,the exceptional performance and promising potential of the proposed model in addressing THM fracturing problems in poro-elastic media is demonstrated.
基金Supported by the National Natural Science Foundation of China(11390363)
文摘In a bird strike, the bird undergoes large deformation like flows; while most part of the structure is in small deformation, the region near the impact point may experience large deformations, even fail. This paper develops a coupled shell-material point method （CSMPM） for bird strike simulation, in which the bird is modeled by the material point method （MPM） and the aircraft structure is modeled by the Belytschko-Lin-Tsay shell element. The interaction between the bird and the structure is handled by a particle-to-surface contact algorithm. The distorted and failed shell elements will be eroded if a certain criterion is reached. The proposed CSMPM takes full advantages of both the finite element method and the MPM for bird strike simulation and is validated by several numerical examples.
基金The financial supports from National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(Grant No.52022112)the International Postdoctoral Exchange Fellowship Program(Talent-Introduction Program,Grant No.YJ20220219)。
文摘The material point method(MPM)has been gaining increasing popularity as an appropriate approach to the solution of coupled hydro-mechanical problems involving large deformation.In this paper,we survey the current state-of-the-art in the MPM simulation of hydro-mechanical behaviour in two-phase porous geomaterials.The review covers the recent advances and developments in the MPM and their extensions to capture the coupled hydro-mechanical problems involving large deformations.The focus of this review is aiming at providing a clear picture of what has or has not been developed or implemented for simulating two-phase coupled large deformation problems,which will provide some direct reference for both practitioners and researchers.
基金funded by National Science Foundation(NSF)(Grant No.CMMI-2211002).
文摘This paper proposed the explicit generalized-a time scheme and periodic boundary conditions in the material point method(MPM)for the simulation of coseismic site response.The proposed boundary condition uses an intuitive particle-relocation algorithm ensuring material points always remain within the computational mesh.The explicit generalized-a time scheme was implemented in MPM to enable the damping of spurious high frequency oscillations.Firstly,the MPM was verified against finite element method(FEM).Secondly,ability of the MPM in capturing the analytical transfer function was investigated.Thirdly,a symmetric embankment was adopted to investigate the effects of ground motion arias intensity(I_(a)),geometry dimensions,and constitutive models.The results show that the larger the model size,the higher the crest runout and settlement for the same ground motion.When using a Mohr-Coulomb model,the crest runout increases with increasing I_(a).However,if the strain-softening law is activated,the results are less influenced by the ground motion.Finally,the MPM results were compared with the Newmark sliding block solution.The simplified analysis herein highlights the capabilities of MPM to capture the full deformation process for earthquake engineering applications,the importance of geometry characterization,and the selection of appropriate constitutive models when simulating coseismic site response and subsequent large deformations.
基金supported by the National Basic Research Program of China (2010CB832701)
文摘As a Lagrangian meshless method, the material point method （MPM） is suitable for dynamic problems with extreme deformation, but its efficiency and accuracy are not as good as that of the finite element method （FEM） for small deformation problems. Therefore, an algorithm for the coupling of FEM and MPM is proposed to take advantages of both methods. Furthermore, a conversion scheme of elements to particles is developed. Hence, the material domain is firstly discretized by finite elements, and then the distorted elements are automatically converted into MPM particles to avoid element entanglement. The interaction between finite elements and MPM particles is implemented based on the background grid in MPM framework. Numerical results are in good agreement with that of both FEM and MPM
文摘随着山区高速公路建设的迅速推进,弃渣场的稳定性及潜在失稳灾害评估日益受到重视。具有巨大能量的滑坡体,可能会冲击破坏沿途的结构物进而威胁生命财产安全。充分发挥利用物质点法(material point method,MPM)可以对连续介质大变形过程模拟和离散元法(digital elevation model,DEM)能够精准的接触判断优势,MPM-DEM耦合算法可有效解决滑坡体与复杂地形、沿线结构物之间的相互作用问题。文章基于GPU并行高性能计算软件CoSim中的MPM-DEM耦合算法,实现了对弃渣场边坡稳定性、潜在失稳灾害的动力学分析。研究首先以散粒体冲击结构物的算例,验证了该算法的合理性与准确性;在此基础上,以云南某高速公路弃渣场为研究案例,进一步计算其稳定性系数,并预测潜在失稳灾害的影响范围与危害程度。结果表明,该弃渣场边坡目前处于稳定状态;若发生失稳,滑坡体将对下游高速公路桥桩产生巨大冲击力。该耦合算法在弃渣场边坡稳定性与失稳灾害动力学分析中具备显著优势,能够实现边坡“稳定性→大变形→流动→堆积”的全过程分析。
文摘深度积分算法可将滑坡沿地表滑动的三维模型化简为二维模型进行求解,通过减少控制方程未知量的个数以提升求解效率。物质点法(material point method,MPM)具有无网格法和有网格法的双重优势,模拟滑坡大变形问题时可避免网格畸变现象。采用深度积分耦合物质点法建立滑坡数值模型,给出算法实现具体流程,基于影响域改进的物质点法(influence domain material point method,IDMPM),针对两个典型无倾角底面光滑和有倾角底面不光滑滑坡算例进行基准测试。在计算精度方面,深度积分耦合物质点法模型能较好地预测远端距离、流速、深度等滑移特征参数;在计算效率方面,与常规物质点法求解格式相比,深度积分耦合物质点法模型可大幅度提高运行效率。该研究成果可为滑坡地质灾害破坏范围的分析预测、危害评估、应急抢险提供有效理论依据和时间保障。
文摘功能梯度材料是一种特殊的复合材料,在高温下能很好地缓解热应力.由于其材料结构和物理力学性质的特殊性,热冲击下功能梯度梁呈现出较为复杂的热力学行为.B样条物质点法作为一种物质点法的改进算法,已在各类复杂问题中展现了强大的求解能力.本文基于傅里叶热传导理论与BSMPM(B-spline Material Point Method)的框架提出了热力耦合方程的离散格式,分析了SiC-Al功能梯度梁的自由振动以及温度荷载作用下的动力响应;同时,基于快速傅里叶变换,研究了SiC-Al功能梯度梁横向振动固有频率随梯度幂律指数的变化规律,并分别与传统物质点法、有限元法和理论解进行了比较分析.结果表明:相较于传统物质点法,B样条物质点法有效改善了应力振荡以及能量耗散.热冲击作用下,B样条物质点法所得功能梯度梁内温度分布与有限元结果吻合较好;B样条物质点法能有效求得一阶横向振动固有频率;随着梯度幂律指数的增加,功能梯度梁固有频率随幂函数变化减小,与理论结果吻合较好.本文验证了热力耦合B样条物质点法的有效性,拓展了B样条物质点法的工程应用,为功能梯度材料在热力耦合作用下的动力响应研究提供了新的计算思路.
