第二章完成第一个简单分析计算样例
by typing the commands from the keyboard, pressing开学第一天感受<Enter>at the end of each command line, and eing the results directly.
new
gen zone brick size 6 8 8
（This command will create an initial mesh that is six zones in the x-direction, eight zones in the玉龙传y吊篮安装规范-direction and eight zones in the z-direction. For our model, the z-axis is oriented in the verticaldirection.）
Plot
（the Plot Ba/0>prompt will appear. As long as this prompt appears, any subquentcommands will be associated with the PLOT command. The plot view is identified asBa/0,which is the default view.）
create Trench
add surface yellow
add axes black
show
Now, give the zones a material model and properties. For this example, we u the Mohr-Coulombelastic-plastic model. Go back to the Flac3D>prompt in the command window andtype in thefollowing command:
modelmohr
This will specify the Mohr-Coulomb model. Every zone in the grid could conceivably have adifferent material model and property. However, by not specifying a range of zonesafter theMODEL command, FLAC3D assumes that all zones are to be Mohr-Coulomb material.
prop bulk = 1e8 shear = 0.3e8 fric = 35
propcoh = 1e10 tens = 1e10
You e that very high cohesion and tensile strength values are given. The areonly initial values that are ud during the development of gravitational stress within the body.In effect, we are forcing the body to behave elastically during the development of theinitial insitustress state.* This prevents any plastic yield during the initial loading pha of theanalysis.
For this problem, loading is due to gravity. To apply gravity, u the commands
tgrav 0, 0, -9.81
ini dens = 1000
In order to develop a gravitational body force, themass density must also be initialized. The INI command is ud to initialize the mass density to1000 kg/m3 for all zones in the model.
红糖姜汤
Next, the boundary conditions for the problem are t. At the Flac3D>prompt, type
fix x range x -0.1 0.1
fix x range x 5.9 6.1
fix y range y -0.1 0.1
fix y range y 7.9 8.1
fix z range z -0.1 0.1
With the commands, roller boundaries are placed on five sides of the model. The boundaries are “fixed” only in the specified direction (i.e., no displacement or velocity is allowed). The FIX commands perform the following functions.
1. The gridpoints along the boundary planes at x = 0 and x = 6 are fixed in the x-direction. The two planes fall within the coordinate ranges specified by the range keywords for the first two FIX commands.
2. The gridpoints along the boundary planes at y = 0 and y = 8 are fixed in the y-direction. The planes fall within the ranges specified for the third and fourth FIX commands.
3. The gridpoints along the bottom boundary (z = 0) are fixed in the z-direction. This plane falls within the range for the fifth FIX command.
We wish to monitor the change in the values of lected variables in the model during the calculational stepping. A HISTORY command can assist in helping us determine whether a stable equilibrium solution or unstable collap is occurring. We type the following commands:
hist n = 5食谱家常菜
histunbal
histgpzdisp 4,4,8
We choo to monitor the change in variables every five calculation steps. It is always a
得意忘形的近义词good idea to monitor the maximum unbalanced force in a model. If the unbalanced force approaches a very small value and displacement histories become constant, this indicates that an equilibrium state is reached.
To allow gravitational stress to develop within the body, we timestep the simulation to equilibrium.Here the SOLVE command is ud to detect equilibrium automatically.
十一年邱永传tmech force=50
solve
When the unbalanced force falls below the limiting value (a limiting force of 50 N is specified with the SET command), the run will stop.* The plots are updated, since they are still visible on the screen. Shutting down the plots will cau the model to cycle faster.
plot
诗人的雅号hist 1
hist 2
The unbalanced force history approaches zero, andthe displacement history becomes constant; both are indicators that an equilibriumstate has beenreached.
Note that each history is numbered quentially from 1 as it is entered via the HIST command. Return to the Flac3D> prompt and type
printhist
for a listing of the histories and their corresponding numbers.
