当前位置:首页 >> 电力/水利 >>

Boundary conditions in FLAC


Boundary Conditions in FLAC

IT CA AS

Boundary Conditions
The prescribed conditions applying to the boundary of the model can be: - Real (e.g., ground surface) - Ar

tificial (e.g, symmetry axes, boundary lines)
Dam boundary (real)

Water table

Model boundary (artificial)

Horizontal boundary stress (artificial)

Excavation boundary (real) Fixed bottom boundary (artificial)

IT CA AS

Clasification of Boundary Conditions

Mechanical boundary conditions in FLAC can be: 1. Stress boundary conditions:
stresses are fixed using the APPLY command

2. Displacement boundary conditions:
gridpoint velocities are fixed using the FIX command

IT CA AS

Sign Convention for Stresses in FLAC
Normal Stress

(-)

(+)

(compression)

(tension)

(-) Surface Pressure

(+)

Shear Stress (+) (-)

(e.g., pore pressure)

IT CA AS

Commands used to apply Boundary Conditions (1)
APPLY keyword < value > < var vx vy > range
(The command applies a stress boundary condition to an external or internal boundary)

keyword

sxx syy sxy xf yf

xx component of the stress applied to the boundary of the model yy component of the stress applied to the boundary of the model xy component of the stress applied to the boundary of the model x component of the force applied to a gridpoint y component of the force applied to a gridpoint

nstress normal component of the stress sstress shear component of the stress value var value of the variable in the origin of the application range vx vy range i=i1,i2 lineal increment of the variable in the x direction, in the application range lineal increment of the variable in the y direction, in the application range j=j1,j2

< keyword > from i1,j1 to i2,j2 < keyword > long: long way of the range

short: short way of the range (by default)

IT CA AS

APPLY Command
Example 1
syy=1MPa

grid 10 10 mo el gen circle 5 5 2.5 mo null reg 5 5 gen adjust apply syy -1e6 j 1 apply syy -1e6 j 11 apply sxx -1e6 i 1 apply sxx -1e6 i 11 plo grid apply

syy=sxx=1MPa

Example 3
grid 10 10 mo el gen circle 5 5 2.5 mo null reg 5 5 syy=sxx=3MPa gen adjust apply syy -3e6 j 1 apply syy -1e6 j 11 apply sxx -3e6 var 0 2e6 i 1 apply sxx -3e6 var 0 2e6 i 11 plo grid apply

Example 2
grid 10 10 mo el gen circle 5 5 2.5 mo null reg 5 5 gen adjust apply syy -1e6 j 1 apply sxx -1e6 var 0 1e6 i 1 apply sxx -1e6 var 0 1e6 i 11 plo grid apply
syy=sxx=0

syy=sxx=1MPa

IT CA AS

Commands used to apply Boundary Conditions (2)
FIX keyword < mark > i = i1, i2 j = j1, j2
(The command applies displacement boundary conditions, fixing the value of the specified variable)

keyword

x y

fix the x component of velocity in the selected range fix the y component of velocity in the selected range

< mark > only the marked gridpoints of the selected range are fixed

This boundary condition can be deleted using the FREE command, which has the same syntax. Displacement boundary conditions can be alternatively applied using APPLY command (xvel, yvel; nvel, svel) using the syntax previously described for this command.

IT CA AS

FIX Command
Example grid 10 10 mo el gen circle 5.0 5.0 2.5 mo null reg 5 5 gen adjust fix x i 1 fix x i 11 fix y j 1 fix y j 11 plot grid fix hold
10.0

gp i=1

gp i=11 gp j=11

8.0

Y axis

6.0

4.0

2.0

0.0

gp j=1

0.0

2.0

4.0

6.0

8.0

10.0

X axis

IT CA AS


相关文章:
ABAQUS常见问题
in solid (continuum) elements 128 nides have dof on which incorrect boundary conditions may 9 nodes have dof on which incorrect boundary conditions may ...
Unsteady boundary conditions in openFOAM
Unsteady boundary conditions in openFOAM_电力/水利_工程科技_专业资料。openfoam边界条件Unsteady boundary conditions in openFOAM By Alberto On August 15, 2008...
FLAC3D5.0详细命令
FLAC3D5.0详细命令_计算机软件及应用_IT/计算机_专业资料。flac3d 5.0命令集锦 ...3、plot text Not all of the following keywords are available in all ...
德语翻译
Landschaft | 地形地貌 Deutschland hat verschiedene Landschaften: das flache ...德国老人学计算机: Heute steht fast in jedem Bü und in jeder Familie ein...
Flac 3D 5.0教程
Go back to the Flac3D>prompt in the command window andtype in the...Boundary conditions are normally specified with the APPLY and FIX/FREE ...
FLAC3D入门基本知识
为了有效的应力求解初始化水力列表条件 5.3.9 Apply Boundary Conditions 应用边界条件 Model boundary conditions are prescribed in FLAC3D with the following ...
流体力学中英文术语
modeling nondimensionalization and, boundary conditions, cavitation number, ...incompressible plane flow in Polar coordinates, Potential flow and, steady plane...
flac3d常用命令
flac3d常用命令_计算机软件及应用_IT/计算机_专业...measured in the negative z-direction from the global...boundary fix x range x -0.1 0.1 表示在 x=...
lammps初学者in文件中文解析
Lammps 初学者——in 文件中文解析 (1)初始化 Units: Units 命令是用来设定...Boundary x y z (x,y,z=p,s,f,m 四种类型中的一种或者两种) P 是...
FLAC3D学习笔记4
coordinates in zone 9703 出错原因: 在同一个单元内的两个节点有相同的坐标, 这可能是由于将其他软件建立的模型 导入到 FLAC3D 时两个软件的节点坐标精度差异所...
更多相关标签:
boundary conditions | in conditions of | in good conditions | tears in heaven flac | back in black flac | inflact | hins in passion flac | oflacin |