University of Puerto Rico at Mayagüez
Department of Mechanical Engineering
Workshop :Bicycle Frame
Design (Optimization)
Modified by (2009): Amabel Reyes
Ana Barriento
Benjamin Ortega
Erick Granadino
University of Puerto Rico at Mayagüez
Thanks to Josymir Lopez Ferrer , enrolled in INME 4058
section 2008
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 ridest he 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.
Problem Description (cont.)
We want to optimize the bars. For this reason, we are assuming that the following
bars will have the same cross-sectional areas:
bars 1 and 4 will have the same cross-sectional area, defined by real constant 1
bars 2 and 3 will have the same cross-sectional area, defined by real constant 2
all other bars will have the same cross-sectional area, defined by real constant 3
.
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.
ANSYS GUI Overview
•
This is ANSYS’s Graphical User Interface window.
UTILITY
MENU:
These are ancillary
functions that are not
directly related to
creating, solving and
selecting results to look
at for you finite model.
Customize this toolbar
with frequency used
commands or create push
button automation with
macros assigned to a
button.
Can type in ANSYS
commands here if you
know them.
RAISE HIDDEN. If a
dialog disappears behind
the main window, bring it
back with this.
THE MAIN MENU. Nodes of the tree expand
and contract. If you collapse a full branch, it
remembers where upon reopening, so you don’t
have to re-drill down to get to that item.
GRAPHICS WINDOWS. This
is where you “plot” things to the
screen.
Manipulate your model
view with buttons.
Look at this! ANSYS will
prompt you for what to do next.
Step 1: Build the model
We have two option:
1.
We
can
find
the
previous
tutorial
and
save
the
HorizontalBendingTest.txt
2.
.
Or, read the HorizontalBendingTest.txt (it runs the tutorial directly)
output
in
Step 2: Go to Design Optimization
Go to Design Opt> Analysis File>
.
a)
Create
b)
Assign… File name is: HorizontalBendingTest.txt
Step 2: Go to Design Optimization
Now Go to utility menu and read the VerticalBendingTestOptimization.txt file (read input)
This is the windows
when ANSYS do
the optimization.
Step 2: Go to Design Optimization
Go to Design Opt> Design Set>List (choose ALL sets). This gives you the various iterations
After the optimization this is
the feasible values of the
diameter of the bicycle
Step 3: Now use this model
From this pointt on you can use this model to perform all other analysis.
.