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Manual of PostGEBT
Qi Wang∗
February 19, 2014
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Introduction
PostGEBT is a post-processing code which can effectively visualize mass
data generated by GEBT. Based on the Variational Asymptotic Method
(VAM) and Decomposition of the Rotation Tensor (DRT), a three-dimensional
(3D) continuum formulation of slender structure can be split into a twodimensional (2D) cross-sectional analysis and a one-dimensional (1D) global
beam analysis. GEBT is a powerful beam solver to calculate the 1D quantities, including displacements and rotations, force and moment resultants,
and linear and angular momenta. These results can be used for optimization and design for displacements or stresses constraints or fatigue constraints. Moreover, the recovery of the 3D mechanical field over the whole
cross-section also needs these 1D global information. PostGEBT reads and
visualizes the results produced by GEBT for static, steady-state, transient
dynamic, and eigenvalue analyses. This manual will serve to help readers get
started using PostGEBT with three examples. More details on the theory
and implementation of GEBT can be found in Ref.[1, 2].
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PostGEBT Functionalities and Examples
2.1
Post-processing for static and steady-state analyses
PostGEBT visualizes
1. Displacements and rotations
∗
Research Engineer at the National Renewable Energy Laboratory.
[email protected]
1
Email:
Figure 1: Sketch of a cantilever beam assembly subjected to a tip force.
Figure 2: Pop-up window for visualization options.
2. Force and moment resultants
in each member defined in GEBT. The plotting x-axis is defined as a nondimensional coordinate η along beam axis x1 . Here is an example of the
visualization of static analysis results. The problem definition is as follows:
it is a cantilever formed with two straight segments, as sketched, with tip load
1000 N. The 1st segment is of length 1m and the 2nd segment is of length
0.5m.The 2nd segment rotated about the 1st segment anticlockwise around
30 degrees, see Figure 1. The input file name is “cantilever2.dat”.
The GEBT input file “cantilever2.dat” and output file “cantilever2.dat.out”
should be put in the same folder along with PostGEBT.exe. When the
users run the executable file “PostGEBT.exe”, a window will pop up (see
Figure 2) asking if the users would like to see the plots in pop-up windows.
The first option “Yes, and save to file” enables the users to see the plots
in pop-up window while the second option “No, save to file only” will not
show the plots automatically. No matter what the option is, the plots will
be saved to PNG format files in the same folder. Next, a pop-up window
will ask the users to provide the input file name used in GEBT, see Figure 3. The resulting figures will be output and saved to the working folder
in PNG format. In this case, the displacements/rotations and force/moment
resultants will be plotted for each member, see Figure 4. The output flies
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Figure 3: Pop-up window for GEBT input file name.
entitled “Disp Member #.png” and “Force Member #.png” can be found
in the working folder, where “#” denotes the member number.
2.2
Post-processing for transient dynamic analysis
For the transient dynamic analysis, users will have the options to plot the
quantities either by Sensor or Survey, which are the concepts defined by
Professor Bauchau in Ref. [3]. If the analysis type in the GEBT input file
is set as “2”, a pop-up window will ask the users what kind of figures they
would like, “Sensor” or “Survey”, see Figure 5.
According to the definition, “sensor” outputs the time histories of various
quantities relating to each member of the model. Specifically, PostGEBT
will visualize the displacements/rotations, force/moment resultants in twodimensional graphs: time is plotted along the x-axis and the quantities
associated with the sensor are plotted along the y-axis. “Survey” outputs
the spatial distribution of various quantities relating to each member of the
model. These quantities will be plotted in two-dimensional graphs: space is
plotted along the x-axis and the quantities associated with the survey are
plotted along the y-axis. If the users choose “sensor”, a window will pop up
asking for the KEY POINT NUMBER for plotting; while if the “survey”
is chosen, the pop-up window will ask for the TIME STEP NUMBER for
plotting, see Figure 6.
The output files for sensor type plotting are “Disp History KP #.png”
and “Force History KP #.png”, respectively, where the “#” denotes the key
point number. The output files for survey type plotting are “Disp Member # Step *.png”
and “Force Member # Step *.png”, respectively, with “#” the member number and “*” the time step number.
2.3
Post-processing for eigenvalue analysis
PostGEBT will visualize the mode shapes obtained by GEBT eigenvalue
analysis and generate a text file entitled ”NaturalFrequency.pgt” where the
values of natural frequency associated with the plotted mode shapes are
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(a) Displacements/Rotations of Member 1
(b) Displacements/Rotations of Member 2
(c) Forces/moments of Member 1
(d) Forces/moments of Member 2
Figure 4: Plots of displacements/rotations and force/moment resultants generated by PostGEBT.
Figure 5: Pop-up window for transient dynamic analysis.
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(a) Pop-up window for sensor plotting
(b) Pop-up window for survey plotting
Figure 6: Pop-up windows for sensor and survey type plotting.
documented. The eigenvectors corresponding to the displacements/rotations
and the force/moment resultants will be plotted. The output files are “Member # Mode * Disp.png” and “Member # Mode * Force.png”, respectively.
The “#” denotes the member number and “*” the mode number.
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Running PostGEBT
PostGEBT is distributed in the form of PostGEBT V# Release.zip for Windows operating systems, with # denoting the version number. The current
version is PostGEBT I. This release package contains an executable file–
“PostGEBT V1.exe” (representing PostGEBT version 1) and three examples for static, transient dynamic, and eigenvalue analyses, respectively. The
c
current PostGEBT application is produced by using Matlab⃝
8.0.0 (2012b)
c
⃝
and MCR version 8.0. For the machines with Matlab software installed,
the users may check their current version of MCR by typing “[major,minor]
= mcrversion” under the Matlab command line. In order to guarantee that
the application works properly on the user’s computer, Matlab requires that
the user and the developer have the same version of MCR. If your version
is the same as the above, you can execute “PostGEBT V1.exe” file directly.
Otherwise, please download and install the MCR(2012b) from the mathwork
website:
http://www.mathworks.com/products/compiler/mcr/
Dr. Qi Wang is committed to maintaining and providing support for
PostGEBT. If you want to customize the output format of the PostGEBT
files or have any questions, please send an Email to [email protected]
asking for the source code or discussing the problems.
5
References
[1] W. Yu and M. Blair. Gebt: A general-purpose nonlinear analysis tool
for composite beams. Composite Structures, 94:2677–2689, 2012.
[2] Dewey H. Hodges. Nonlinear Composite Beam Theory for Engineers.
AIAA, Washington DC, 2006.
[3] O.
A.
Bauchau.
Dymore
User’s
Manual,
2013.
http://dymoresolutions.com/dymore4 0/UsersManual/UsersManual.html.
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