基于光滑粒子流体动力学-有限元法(smoothed particle hydrodynamics-finite element method,SPH-FEM)耦合的数值方法,分别从结构破坏形态、冲击力时程、关键点位移和速度、系统能量等方面,研究含大石块泥石流冲击作用下框架结构房屋的...基于光滑粒子流体动力学-有限元法(smoothed particle hydrodynamics-finite element method,SPH-FEM)耦合的数值方法,分别从结构破坏形态、冲击力时程、关键点位移和速度、系统能量等方面,研究含大石块泥石流冲击作用下框架结构房屋的动力响应和破坏机理。计算结果表明:SPH-FEM耦合方法能够较好地模拟泥石流冲击爬高、绕流扩散、淤积稳定过程。考虑了三种泥石流强度等级,在低、中强度冲击情况下,框架房屋填充墙受到破坏,房屋结构整体保持稳定;在高强度冲击情况下,可以观察到框架房屋的逐步倒塌过程,框架柱损坏模式体现了剪切破坏或塑性铰链失效机制。对于房屋结构而言,泥石流的冲击破坏能力主要来自龙头的冲击力,龙身冲击力相对于龙头降幅约34.2%,大石块的集中作用是结构柱体局部破坏的主要原因。系统能量主要通过泥石流动能转化为结构内能(17.8%)和摩擦耗能(82.8%)。展开更多
随着电子设备日益微型化和集成化,热仿真已成为其设计中的关键因素。电子封装模块的热仿真通常使用传统的有限元法FEM(finite element method),存在计算效率和精度之间的矛盾,在处理大变形问题和网格畸变方面也容易造成计算不收敛,从而...随着电子设备日益微型化和集成化,热仿真已成为其设计中的关键因素。电子封装模块的热仿真通常使用传统的有限元法FEM(finite element method),存在计算效率和精度之间的矛盾,在处理大变形问题和网格畸变方面也容易造成计算不收敛,从而导致结果错误。针对该问题,提出一种基于光滑粒子动力学SPH(smoothed particle hydrodynamics)算法的电子封装模块热仿真系统。该算法基于无网格拉格朗日数值方法,通过将热仿真对象离散为1组粒子的方式求解热传导方程,从而准确地预测电子封装模块的传热与散热,无需生成并处理大量的微小网格,不用担心网格失真等问题。SPH相对于FEM,仿真精度误差保持在1%~2%,仿真效率可提升近30倍,适合用于复杂和动态系统的模拟仿真。展开更多
Free-surface flows, especially those associated with fluid-structure interactions(FSIs), pose challenging problems in numerical simulations. The authors of this work recently developed a smoothed particle element meth...Free-surface flows, especially those associated with fluid-structure interactions(FSIs), pose challenging problems in numerical simulations. The authors of this work recently developed a smoothed particle element method(SPEM) to simulate FSIs. In this method, both the fluid and solid regions are initially modeled using a smoothed finite element method(S-FEM) in a Lagrangian frame, whereas the fluid regions undergoing large deformations are adaptively converted into particles and modeled with an improved smoothed particle hydrodynamics(SPH) method. This approach greatly improves computational accuracy and efficiency because of the advantages of the S-FEM in efficiently treating solid/fluid regions showing small deformations and the SPH method in effectively modeling moving interfaces. In this work, we further enhance the efficiency of the SPEM while effectively capturing local fluid information by introducing a multi-resolution technique to the SPEM and developing an effective approach to treat multi-resolution element-particle interfaces. Various numerical examples demonstrate that the multiresolution SPEM can significantly reduce the computational cost relative to the original version with a constant resolution.Moreover, the novel approach is effective in modeling various incompressible flow problems involving FSIs.展开更多
针对以往有限元模型中弹丸数量较少且为规则阵列排布的缺陷,采用光滑粒子流体动力学法(Smoothed particle hydrodynamics,SPH)与有限元法(Finite element method,FEM)相结合的方法,对喷丸过程进行数值模拟;使用MATLAB对弹丸空间位置坐...针对以往有限元模型中弹丸数量较少且为规则阵列排布的缺陷,采用光滑粒子流体动力学法(Smoothed particle hydrodynamics,SPH)与有限元法(Finite element method,FEM)相结合的方法,对喷丸过程进行数值模拟;使用MATLAB对弹丸空间位置坐标进行随机化处理,形成了大量丸粒冲击工件表面的随机喷丸仿真模型。通过分析确定了喷丸饱和时间,研究了喷射角度、弹丸流量对残余应力场的影响。结果表明:在喷丸参数一定的条件下,存在相应的饱和喷丸时间;研究喷丸参数对残余应力的影响时,应在喷丸达到饱和时间之后提取残余应力值;喷射角度增大,残余压应力增大;开始时弹丸流量增大,残余压应力会有所增大,但当其达到饱和值后,残余压应力不再变化。展开更多
文摘基于光滑粒子流体动力学-有限元法(smoothed particle hydrodynamics-finite element method,SPH-FEM)耦合的数值方法,分别从结构破坏形态、冲击力时程、关键点位移和速度、系统能量等方面,研究含大石块泥石流冲击作用下框架结构房屋的动力响应和破坏机理。计算结果表明:SPH-FEM耦合方法能够较好地模拟泥石流冲击爬高、绕流扩散、淤积稳定过程。考虑了三种泥石流强度等级,在低、中强度冲击情况下,框架房屋填充墙受到破坏,房屋结构整体保持稳定;在高强度冲击情况下,可以观察到框架房屋的逐步倒塌过程,框架柱损坏模式体现了剪切破坏或塑性铰链失效机制。对于房屋结构而言,泥石流的冲击破坏能力主要来自龙头的冲击力,龙身冲击力相对于龙头降幅约34.2%,大石块的集中作用是结构柱体局部破坏的主要原因。系统能量主要通过泥石流动能转化为结构内能(17.8%)和摩擦耗能(82.8%)。
文摘随着电子设备日益微型化和集成化,热仿真已成为其设计中的关键因素。电子封装模块的热仿真通常使用传统的有限元法FEM(finite element method),存在计算效率和精度之间的矛盾,在处理大变形问题和网格畸变方面也容易造成计算不收敛,从而导致结果错误。针对该问题,提出一种基于光滑粒子动力学SPH(smoothed particle hydrodynamics)算法的电子封装模块热仿真系统。该算法基于无网格拉格朗日数值方法,通过将热仿真对象离散为1组粒子的方式求解热传导方程,从而准确地预测电子封装模块的传热与散热,无需生成并处理大量的微小网格,不用担心网格失真等问题。SPH相对于FEM,仿真精度误差保持在1%~2%,仿真效率可提升近30倍,适合用于复杂和动态系统的模拟仿真。
基金supported by the National Numerical Wind Tunnel Project (Grant No. NNW2019ZT2-B02)the National Natural Science Foundation of China (Grant Nos. 12032002,51779003,and 11902005)the SinoGerman Mobility Programme (Grant No. M-0210)。
文摘Free-surface flows, especially those associated with fluid-structure interactions(FSIs), pose challenging problems in numerical simulations. The authors of this work recently developed a smoothed particle element method(SPEM) to simulate FSIs. In this method, both the fluid and solid regions are initially modeled using a smoothed finite element method(S-FEM) in a Lagrangian frame, whereas the fluid regions undergoing large deformations are adaptively converted into particles and modeled with an improved smoothed particle hydrodynamics(SPH) method. This approach greatly improves computational accuracy and efficiency because of the advantages of the S-FEM in efficiently treating solid/fluid regions showing small deformations and the SPH method in effectively modeling moving interfaces. In this work, we further enhance the efficiency of the SPEM while effectively capturing local fluid information by introducing a multi-resolution technique to the SPEM and developing an effective approach to treat multi-resolution element-particle interfaces. Various numerical examples demonstrate that the multiresolution SPEM can significantly reduce the computational cost relative to the original version with a constant resolution.Moreover, the novel approach is effective in modeling various incompressible flow problems involving FSIs.
文摘针对以往有限元模型中弹丸数量较少且为规则阵列排布的缺陷,采用光滑粒子流体动力学法(Smoothed particle hydrodynamics,SPH)与有限元法(Finite element method,FEM)相结合的方法,对喷丸过程进行数值模拟;使用MATLAB对弹丸空间位置坐标进行随机化处理,形成了大量丸粒冲击工件表面的随机喷丸仿真模型。通过分析确定了喷丸饱和时间,研究了喷射角度、弹丸流量对残余应力场的影响。结果表明:在喷丸参数一定的条件下,存在相应的饱和喷丸时间;研究喷丸参数对残余应力的影响时,应在喷丸达到饱和时间之后提取残余应力值;喷射角度增大,残余压应力增大;开始时弹丸流量增大,残余压应力会有所增大,但当其达到饱和值后,残余压应力不再变化。
