Taking the strain tensor, the scalar damage variable, and the damage gradient as the state variables of the Helmholtz free energy, the general expressions of the firstorder gradient damage constitutive equations are d...Taking the strain tensor, the scalar damage variable, and the damage gradient as the state variables of the Helmholtz free energy, the general expressions of the firstorder gradient damage constitutive equations are derived directly from the basic law of irreversible thermodynamics with the constitutive functional expansion method at the natural state. When the damage variable is equal to zero, the expressions can be simplified to the linear elastic constitutive equations. When the damage gradient vanishes, the expressions can be simplified to the classical damage constitutive equations based on the strain equivalence hypothesis. A one-dimensional problem is presented to indicate that the damage field changes from the non-periodic solutions to the spatial periodic-like solutions with stress increment. The peak value region develops a localization band. The onset mechanism of strain localization is proposed. Damage localization emerges after damage occurs for a short time. The width of the localization band is proportional to the internal characteristic length.展开更多
基于Volume of Fluid(VOF)模型对二维溃坝经典案例进行模拟,通过与实验值进行对比,验证VOF模型的计算精度。针对二维溃坝下游有障碍物的情况,研究不同时刻的流场变化情况,与实验结果比较分析,并对障碍物所受到的压力进行分析。通过更改...基于Volume of Fluid(VOF)模型对二维溃坝经典案例进行模拟,通过与实验值进行对比,验证VOF模型的计算精度。针对二维溃坝下游有障碍物的情况,研究不同时刻的流场变化情况,与实验结果比较分析,并对障碍物所受到的压力进行分析。通过更改障碍物的位置,研究不同障碍物位置对溃坝水流的影响,不同障碍物位置所受到的压力。结果表明:VOF可以很好地模拟溃坝水流。对于下游有障碍物的溃坝模型,障碍物的最低点所受到的压力最大,最高点所受到的压力最小。障碍物位置距离溃坝水流越远,受到的压力越大,液面变化越剧烈,溃坝水流撞击障碍物行成的水舌高度越高,飞溅的水体也相应增加,水舌撞击右壁面的高度越大。展开更多
基金Project supported by the National Natural Science Foundation of China (No. 50978036)the Natural Science Foundation of Hunan Province of China (No. 09JJ6080)the Applied Basic Research Programs of Ministry of Transportation of China (No. 2009-319-825-100)
文摘Taking the strain tensor, the scalar damage variable, and the damage gradient as the state variables of the Helmholtz free energy, the general expressions of the firstorder gradient damage constitutive equations are derived directly from the basic law of irreversible thermodynamics with the constitutive functional expansion method at the natural state. When the damage variable is equal to zero, the expressions can be simplified to the linear elastic constitutive equations. When the damage gradient vanishes, the expressions can be simplified to the classical damage constitutive equations based on the strain equivalence hypothesis. A one-dimensional problem is presented to indicate that the damage field changes from the non-periodic solutions to the spatial periodic-like solutions with stress increment. The peak value region develops a localization band. The onset mechanism of strain localization is proposed. Damage localization emerges after damage occurs for a short time. The width of the localization band is proportional to the internal characteristic length.
文摘基于Volume of Fluid(VOF)模型对二维溃坝经典案例进行模拟,通过与实验值进行对比,验证VOF模型的计算精度。针对二维溃坝下游有障碍物的情况,研究不同时刻的流场变化情况,与实验结果比较分析,并对障碍物所受到的压力进行分析。通过更改障碍物的位置,研究不同障碍物位置对溃坝水流的影响,不同障碍物位置所受到的压力。结果表明:VOF可以很好地模拟溃坝水流。对于下游有障碍物的溃坝模型,障碍物的最低点所受到的压力最大,最高点所受到的压力最小。障碍物位置距离溃坝水流越远,受到的压力越大,液面变化越剧烈,溃坝水流撞击障碍物行成的水舌高度越高,飞溅的水体也相应增加,水舌撞击右壁面的高度越大。
