Department of Mechanical Engineering
University of Puerto Rico, Mayagüez
Workshop: Bicycle Frame Design
Modified by (2009):
Neysa A. Fuentes
Department of Mechanical Engineering
University of Puerto Rico, Mayagüez
Jelisa Torres Ramos
Department of Mechanical Engineering
University of Puerto Rico, Mayagüez
http://touringdane.files.wordpress.com/2008/07/bicycle_parts_labeled.jpg
Jose R. Vázquez
Department of Mechanical Engineering
University of Puerto Rico, Mayagüez
Prof Vijay K. Goyal, Ph.D.
Associate Professor, Department of Mechanical Engineering
University of Puerto Rico at Mayagüez
Problem Description
This is a simple static analysis of a frame of bicycle using a hollow aluminum
tube. The schematic dimensions of the bicycle are shown in the figure 1.
Initially, the flowing cross-sectional dimensions are used for all frames: Outer
diameter φ = 25mm and Thickness t =2mm
The material properties of aluminum are:
Material Properties
Values
Young’s Modulus (E)
70 Gpa
Poisson’s Ration (ν)
0.33
Density (ρ)
2,580 kg/m3
Ultimate Tensile Strength(σU)
210 Mpa
Elongation at Break
10 %
Problem Description (cont.)
Even if the bike is under the dynamic loads, only two static design criteria are considered
here, the vertical bending test and the horizontal Impact.
Vertical bending test:
When an adult ride the bike, the nominal load can be estimated by the vertically
downward load of 600N at the seat position and a load of 200N at the pedal crank location.
When a dynamic environment is simulated using the static analysis, the static loads are
often multiplied by a certain “G-factor”. In this design project, use G = 2. Use ball-joint
boundary condition for the front dropout ( 1 ) and sliding boundary condition for rear
dropouts ( 5 and 6 ).
Horizontal Impact:
The BNA’s (Bureau of National Affairs) “Requirements for Bicycles” manual calls for a
single compressive loading test. A load of 980N is applied to the front dropout horizontally
with rear dropouts constrained from any translational motion. Use G = 2. For this case the
weight of the person (1200N) in the bike will also be considered in addition to the load at the
bike pedals (400N) both of these loads have already been multiplied by the G factor.
Starting ANSYS

From your desktop:
Click on: START > All Programs >
ANSYS 11.0 >
ANSYS Product Launcher.

Here we will set our Working Directory
and the Graphics Manager
Working Directory Setup
•
This is the
11.0 ANSYS
Product Launcher
main window.
•
Select the Working
Directory and type
the name of work
shop on Job Name.
Graphics Setup
•
Click the button:
Customization/Preferences.
•
On the item of Use custom
memory settings type 128
on Total Workspace (MB):
and type 64 on
Database (MB):
•
Then click the Run
bottom.
* This setup applies to computers running under 512 MB of RAM
ANSYS GUI Overview
•
This is ANSYS’s Graphical User Interface window.
Step 1: Set Preferences

We’ll set preferences in order to filter quantities that relate to this discipline only.

Click Preferences from ANSYS Main Menu.

Select (check): “Structural ” & h-Method ”
Step 2: Element Type
Define element Types
1) Go to ANSYS Main Menu > Preprocessor > Element type > Add/Edit/Delete
2) In the display window named Element Type Click ADD
In the new display window select pipe and Elast straight 16
3) Then click OK on Library of Element Types and CLOSE on the window of Element Types
1
2
3
Step 2: Element Type

You should have one element type on the Element Types window
•
Step 3: Real constants
This part is to enter the dimensions of the tube:
• Outer diameter φ = 25mm and Thickness t =2mm
Go to ANSYS Main Menu > Real Constants > Add/Edit/Delete > Add > OK
IMPORTAT!!!
You have to use all the dimension on the same unit since ANSYS is a
dimensionless Program.
We will use all the dimensions on meters > Add the values
φ =.025 and t =.002 > OK > The window of Real Constants (3) now said SET 1 >
CLOSE
1
2
3
Step 4: Define Materials
Now we are going to define the bicycle frame constant material properties. We are going to
define the material’s behavior and then we’ll define Young’s Modulus (E), poison’s ratio (ν), and
density (ρ).
GO to ANSYS Main Menu > Preprocessor > Material Properties > Material Models
A new window ‘Define Material Model Behavior (1) will appear, on this window make a Doubleclick on Structural > Linear > Elastic > Isotropic > a new window will appear (2) > put the
values of Young’s Modulus (E) and poison’s ratio (ν) > OK > CLOSE
To enter the value of density > Double-click on Density (3)> enter the value > OK > CLOSE
2
1
3
Step 5: Build Geometry
We’ll start by creating keypoints
– Keypoints: These are points, locations in 3D space.
ANSYS Main Menu > Preprocessor > Modeling > Create > Keypoints
> In active CS
Enter 1 for Keypoint Number, enter 0, 0.325, 0 for X, Y, Z respectively. Click
Apply , @ keypoint #8 click ok instead of apply.
Keypoints
X
(m)
Y
(m)
Z
(m)
1
2
3
4
5
6
7
8
0
0
0.500
0.400
.825
0.825
0.400
0.400
0.325
0.400
0.400
0
0
0
0
0
0
-0.020
0
0
0.050
-0.050
0.010
-0.010
Step 4: Build Geometry
Make the same for the next seven Keypoints (don’t forget to change the Keypoint Number),
we have a total of eight Keypoints .
After put the values of Keypoint 8, press OK , don’t press APPLY, if you press APPLY, press
CANCEL.
Enter 2 for Keypoint Number, enter 0, 0.400, -0.020 for X,Y,Z
respectively. Click Apply
Enter 3 for Keypoint Number, enter 0.500, 0.400, 0 for X,Y,Z
respectively. Click Apply
Enter 4 for Keypoint Number, enter 0.400, 0 , 0 for X,Y,Z
respectively. Click Apply
Enter 5 for Keypoint Number, enter 0.825, 0, 0.050 for X,Y,Z
respectively. Click Apply
Enter 6 for Keypoint Number, enter 0.825, 0, -0.050 for X,Y,Z
respectively. Click Apply
Enter 7 for Keypoint Number, enter 0.400, 0, 0.010 for X,Y,Z
respectively. Click Apply
Enter 8 for Keypoint Number, enter 0.400, 0, -0.010 for X,Y,Z
respectively. Click OK
Display Window after creating all eight Keypoints
Choosing Isometric view on the right menu
Step 4: Build Geometry
CREATING THE LINES to make the bicycle frame
Now we are going to create lines that will connect the keypoints, we can made this
using two different procedures, using the ANSYS Main Menu or using codes. For
this type of geometry is more appropriate use CODES.
Using Main Menu:
We’ll start by creating straight lines from keypoint 1 to 2.
Main Menu > Preprocessor > Modeling > Create > Lines > Lines
> Straight Lines
– This feature creates a straight line between two points.
For the first Line select keypoints 1 and 2 and for the second line select keypoints 2
and 3 and continue with the other lines. Click Apply and OK
Step 4: Build Geometry
Using Main Menu:
Step 4: Build Geometry
Using the CODES:
In the ANSYS Command Prompt
L,1,2
L,2,3
L,3,4
L,4,7
L,4,8
L,7,5
L,8,6
L,5,6
L,1,4
L,3,5
L,3,6
“Lines, node, node”
Geometry after adding the 11 lines (elements)
Step 4: Build Geometry
Glue all the lines together!!!
Step 5: Create Mesh
Here we’ll define the meshing for our bicycle frame.
ANSYS Main Menu > Preprocessor > Meshing > Size control > ManualSize > Lines > All Lines
In SIZE Element edge length 0.020
Click OK
Step 5: Create Mesh
ANSYS Main Menu > Preprocessor
> Meshing > Mesh > lines
On the window named Mesh Lines
> OK
Save your JOB!!!
Utility Menu > File > Save as...
Put the name that you want!
Step 6: Define Loads
Horizontal Impact:
The BNA’s (Bureau of National Affairs) “Requirements for Bicycles” manual calls
for a single compressive loading test. A load of 980N is applied to the front
dropout horizontally with rear dropouts constrained from any translational
motion. Use G = 2. Therefore a load of 1960N is applied to the front dropout
horizontally in addition to a load at keypoint 3 of 1200N and a load of 400N to
keypoint 4.
Before apply the constrains go to Preprocessor > Loads > Analysis Type
> New Analysis > static > OK
Step 6: Define Loads
Keypoint 1
Preprocessor > Loads > Define loads > Apply > Structural >
Displacements > On keypoints > Select the keypoints 1 > Select UY, UZ
Keypoint 5 and 6
Preprocessor > Loads > Define loads > Apply > Structural >
Displacements > On keypoints > Select the keypoints 5 and 6
Select All DOF > OK
Final view after apply the constrains
Step 6: Apply Loads
Go to Loads > Define Load > Structural > Force/Moment > On Keypoints >
select key point 1 > OK
In Lab Direction Of Force/Mon > select FX
In apply as > constant value
In VALUE Force/moment value > enter the 1960 > OK
Go to Loads > Define Load > Structural > Force/Moment > On Keypoints >
select key point 3 > OK
In Lab Direction Of Force/Mon > select FY
In apply as > constant value
In VALUE Force/moment value > enter the -1200 > OK
Go to Loads > Define Load > Structural > Force/Moment > On Keypoints >
select key point 4 > OK
In Lab Direction Of Force/Mon > select FX
In apply as > constant value
In VALUE Force/moment value > enter the -400 > OK
1
2
3
Step 6: Apply Loads
Step 7: Obtain Solution
ANSYS Main Menu > Solution > Analysis Type >New Analysis
Click on Static (or choose corresponding analysis type), then click ok
Step 7: Obtain Solution
ANSYS Main Menu > Solution > Solve >Current LS
Click on OK
Step 7.5: Get Happy!
Step 8: Review Results
• To see a 3D go to .. PlotCtrls > Style > Size
and shape > [/Eshape] Display element >
ON > OK
Step 8: Review Results
To see the Deformation
General Postproc > Plot Results > Deformed Shape > on
the new window > Def + underformed > OK
Step 8: Review Results
Step 8: Review Results
Deflections: Nodal Solution
General Postproc > Plot Results > Contour plot > Nodal solution
On the Display Window > select Nodal Solution > DOF Solution >
Displacement vector sum
On Undisplaced shape key > select
Deformed shape (or your preference)
>OK
Step 8: Review Results
Stresses - Von Misses
General Postproc > Plot Results> Contour
Plot > Nodal Solution On the display window
> Stress> Von Mises Stress >
Ok !!
Cross Section
For a cross section … Go to menu.. WorkPLane
> Display working plane..
An additional 3 axes appears, that is your
working plane.
Go to… WorkPLane > Offset WP to > by nodes
> select the node closest to the cross section
that you want > OK
Selected node
Cross Section
(1) Then go to… WorkPLane > Offset WP by
Increments…
And play with the movement of the working plane… It is
also useful to rotate in the different axis to get the
orientation you want.
Remember you want to cut the cross section with the
planes X and Y.
(2) PlotCtrls > Style >
Hidden line Options..
(3) In the display
window in [/TYPE]
Type of plot .. Select SECTION > OK
(4) Play with the view until obtain
cross section
Cross Section
WY
WX
Basic idea, use planes WX & WY
to cut a cross section of the
desired part in the tube.
WZ
Cross Section
It also helps to use the Dynamic Model Mode
rotate the model by right clicking and dragging.
Bending moment
Select General Postproc>Element Table
> Define Table... to define the table (remember SMISC,6 and
SMISC,12)
ADD > by sequence num > SMISC and put , 6 > apply , put
12 and OK > close
Bending moment
• To see the bending moment plots first go back to
PlotCtrls > Style > Hidden line Options
Change in [/TYPE] to Z-buffered
Click OK
Bending moment
And, General Postproc> Plot Results
>Contour Plot > Line Elem Res... to plot
the data from the Element Table > choose
and OK
Bending moment
Optimization
Go to… Design Opt > Analysis File > Assign
Browse for the file used to run the FEM Analysis