Instructions for Running SectionBuilder

O. A. Bauchau

J. I. Craig

AE3125 Spring 2007

Motivation• Hand calculation of stress and shear flows on beam

sections can be a tedious and time-consuming process very prone to errors…

• SectionBuilder is a program developed by Prof. Bauchau to numerically compute stresses and shear flows on beam cross sections.

• Because creating input files to analyze is also tedious, a collection of “templates” has been created. These template files parametrically define a number of common beam sections.

• By modifying the parameters in a template, you should be able to explore a wide range of beam cross section designs.

• NOTE: this is a first release of SectionBuilder and there are some interface problems that you may encounter; you will also have a limited number of options for now. These are being corrected…

Using SectionBuilder

• SectionBuilder is installed on all computers in the AE Computer Lab that have LCD screens.

• A read-only set of section templates is located in the AE3125 share and in C:\SectionBuilder\Demos.

• You should copy the Demos folder to a folder on your H: drive (i.e., H:\ae3125\work).

• NOTE: you should not use spaces in the file names or unpredictable behavior may occur!

Demo ChoicesOpen the folder corresponding to the type of section you wish to analyze:

Airf Airfoil Dbox Two-Cell Box Tria Triangular Section

Carc Circular Arc Isec I-Section Tsec T-Section

Csec C-Channel Rbox Rectangular Box Tube Circular Tube

Cyld Solid Circular Cylinder

Rect Solid Rectangular Section

Running the Dbox Demo

• First, double click clean.bat – Runs the batch file clean.bat– This clears out old unnecessary files

• Next, make a copy of dbox1.seb & dbox.sbf (BOTH files)– Right-click on the icons and drag to an open area in the window– Rename to your project, i.e., test.seb & test.sbf (make sure

NOT to include any spaces in name)• Double-click on the test.seb icon

– This should bring up SectionBuilder – See the next slide

1. There are several different dbox demo files…

What You Should See Next

1. Click on the Mesh button to read the input file.

2. This will cause the FEM button to be highlighted.

Do not use any other

menus before clicking the

Mesh button!

3. Click on the Disk icon to save the current model.

Files that are Created

• Several files are created on Save:– .out – .sbf.bak– .sbg.bak– .html– .sva

• These files contain setup info for now.

Modifying the Section1. Pull down Sections menu and

select Double box (all other choices should be grayed out)

2. Select dbox1 and press the Edit button.

3. Leave the name and Mesh Density alone, and select the Dimensions tab.

Modifying the Section1. Click these 7 buttons to define

the geometry of the section.

2. Enter the dimensions for the “Top left flange” here. See the SectionBuilder manual for details of section geometry.

3. Repeat for each of the buttons defining the section geometry. Click OK when done.

For this particular section the following dimensions are required to be greater than zero:

Left Web ThicknessRight Web ThicknessWeb HeightTop Left Flange Width

See next slides for section geometry

What the Dbox Dimensions Mean

Dimensions:

A: Web Height (required)

B: Top Left Flange (required)

C: Top Right Flange Width

(if set to zero, defaults to Top Left Flange Width)

D: Bottom Left Flange Width

(if set to zero, defaults to Top Left Flange Width)

E: Bottom Right Flange Width

(if set to zero, defaults to Top Left Flange Width)

IMPORTANT NOTES:

The coordinate system origin is located at the boundary between the left web and right web at 0.5*(Web Height)

The x1 direction is axial, the x2 direction is horizontal, and the x3 direction is vertical

What the Dbox Dimensions Mean

Dimensions:A: Left Web Thickness (required) B: Right Web Thickness (required)C: Top Left Flange Thickness

(if set to zero, defaults to Left Web Thickness)D: Top Right Flange Thickness

(if set to zero, defaults to Right Web Thickness)E: Bottom Left Flange Thickness

(if set to zero, defaults to Left Web Thickness)F: Bottom Right Flange Thickness

(if set to zero, defaults to Right Web Thickness)G: Left Wall Thickness

(if set to zero, defaults to Left Web Thickness)H: Right Wall Thickness

(if set to zero, defaults to Right Web Thickness)I: Top Reinforcement Thickness

(if set to zero, reinforcement is omitted)J: Bottom Reinforcement Thickness

(if set to zero, reinforcement is omitted)

What the Dbox Dimensions Mean

Dimensions in degrees

Sign Conventions indicated by arrows

A: Top Left Flange Skew Angle (default zero)

B: Top Right Flange Skew Angle (default zero)

C: Bottom Left Flange Skew Angle (default zero)

D: Bottom Right Flange Skew Angle (default zero)

Selecting Materials

• Left Web Material applies to:– Left Web– Top Left Flange– Bottom Left Flange– Left Wall

• Right Web Material applies to:– Right Web– Top Right Flange– Bottom Right Flange– Right Wall

• Top Flange Material applies to top reinforcement

• Bottom Flange Material applies to bottom reinforcement

1. Choose Materials tab.2. Click buttons to define material

for a region of section.

3. Use pull-down menu to select one of the predefined Materials.

4. Click OK (both windows).5. Click OK to close Object selector window.

Changing the Loading• You can edit, delete or create

new sectional loadings using the Loadings menu and selecting Sectional Loads

1. Choose Loading menu.2. Select loading to edit (or create

a new loading).

3. Click Applied moments to edit.

4. Edit the M1 moment.

Scaling factor

has the same

effect… Be careful to not define inconsistent sectional loadings

5. Click OK (3 times).

What You Should See Next

1. Click the Disk button to save the model.

2. Next, click the Mesh button to re-mesh the model.

Running the Analysis

1. Click the FEM button to run the computational analysis.

Analysis Results

• If everything worked, several files should have been created

• The files all have the same name (test) but with different extensions.

• They are all text files– .out = log file– .sva = loads file– .sbp = sectional properties– .sbs = sensor output file– .sbg = sensor names– .html = full input file

What You Should See Now

1. Next, click the Visualize button to display the model and analysis results.

The Visualizer Window

Loading selection

Current loading in Visualizer

Visualizer controls

Output display selection

Displaying Principal Axes/Centers

B = bending & centroid

S = shear center

I = center of mass, moments of inertia

Display Principal Axes and cross section centers

Selecting Field to Visualize

Display warping, strains, stresses, reserve factor

Notes on Field Outputs• Stresses and Strains

– Displayed as vectors– In-plane quantities will appear in-plane, and out-of-

plane will appear aligned along x1 axis– Thus, the viewport must be rotated to see axial

stress/strain vectors (use controls on screen right)

• Warping Displacements– Cross-sectional warping shape is shown– Therefore, as with axial quantities, the viewport must

be rotated to see warping

• Reserve Factors– Reserve Factors are displayed aligned with x1 axis

(see note later on definition of Reserve Factor)

Example – Visualizing Warping w/out Rotating Viewport

Warping displacement is in x1 direction (perpendicular to viewing plane)

Example – Visualizing Warping after Rotating Viewport

Visualizer controls used to rotate section in order to see warping.

Same controls are in Graphics menu.

Use Ctrl- or Ctrl- to adjust display amplitude.

What is a Reserve Factor?

• Failure conditions can be written as f(σ)≥1 where σ represents the stress state at a point and f(σ) is a function of the stress state (e.g., von Mises stress).

• The reserve factor, is defined as the value, r, such that f(r σ)=1– r >1 implies failure has not occurred at that point– r <1 implies failure has occurred at that point

• Note that when Reserve Factor is visualized in the Visualizer, r -1 is actually displayed– Higher values of r -1 indicate point is closer to failure– Output text file reports values of r, not r -1

• Failure criteria are automatically supplied by SectionBuilder upon selecting a material

Querying Element Quantities

• First, click on one of the field selection buttons:

– Clicking Displacements enables querying local displacements.

– Clicking Axial Strains or Shear Strains enables querying local strains.

– Clicking Axial Stresses, Shear Stresses, or Reserve Factors enables querying local stresses.

• Next, click Element Selection and then click on the element you wish to query. This should highlight the element’s border.

• Finally, click Display Element Stresses.

Display a field ()

Element selection

Display element stresses

An Example

Note highlighted element

Creating a Sensor

• Create a Sensor to send element values to the output file.

• Click Element Selection button and then click on the element you wish to attach a sensor to. This should highlight the element’s border.

• Next, click Create Sensor button.

Element selection

Create Sensor

Creating a Sensor• In the Sensor dialog:

– Enter a Sensor name– Select the Sensor output: stress,

strain, or warping (displacement)– Select location in element where

field variables are calculated

• Create as many sensors as you want/need

• Click Save (VERY IMPORTANT)• You must run the complete

analysis again for the sensor output to be included in the output file:– Click Mesh button– Click FEM button– Click Visualizer button

Opening the Output Files

• The SectionBuilder output is contained in several files.

• You can use your favorite text editor (i.e. Notepad) to open them

What the .OUT File Looks Like

• This file contains the execution log

Sensor Output• The sensor output appears in the test.sbs file (in this

example there are other sensors you can scroll through):

Stiffness/Compliance Matrices• This output appears in the test.sbp file (in this example there are

other sectional properties you can scroll through):

Stiffness/Compliance Matrices• The full sectional stiffness and compliance matrices are

also available.

Applied Sectional Loads• This output appears in the test.sva file and can be

used to confirm your applied loads.

More Output

• Also, you can find location of the various cross-sectional centers

Tips & Techniques

• The SectionBuilder interface is still being improved so you may encounter a premature program termination. This shouldn’t cause any harm or loss of data.

• Remember to Save your model whenever the Mesh, FEM & Visualizer buttons are grayed out.

• When making changes to loading or sensors or materials, you must Save the model, then click the Mesh, FEM and Visualizer buttons in sequence. Note that in such cases, the buttons are not always grayed out so make sure you click in order and wait a few seconds between clicks.

Seeking Help

• If you have any problems running SectionBuilder, getting it to do what you want, or encounter a bug:

• Contact the course TA: Waqas Majeed:– majeed.waqas@gatech.edu– Office: ESM G-10, – Hours: Mon 12-1 & Wed 2-3