Workshop:bicycle Frame Design (optimization): University Of Puerto Rico At Mayagüez Department Of Mechanical Engineering

University of Puerto Rico at Mayagüez Department of Mechanical Engineering

Workshop :Bicycle Frame Design (Optimization) Modified by (2009): Dr. Vijay K. Goyal Associate Professor, Department of Mechanical Engineering 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:

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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 the static design criteria is considered here: due to vertical bending. Vertical bending test: When an adult rides 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 ).

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

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Starting ANSYS

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From your desktop: Click on: START > All Programs > ANSYS > ANSYS Product Launcher.

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Here we will set our Working Directory and the Graphics Manager

Working Directory Setup

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Select the Working Directory and type the name of work shop on Job Name.

Graphics Setup •

Click the button: Customization/Preferences.

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On the item of Use custom memory settings type 128 on Total Workspace (MB): and type 64 on Database (MB):

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Then click the Run bottom.

* This setup applies to computers running under 512 MB of RAM

Go to customization preferences and choose custom memory settings and give values of 128 and 64 for the total workspace and database memory respectively.

Click Run to start

ANSYS GUI Overview •

This is ANSYS’s Graphical User Interface window.

Step 1: Build the model We have two option:

1.

We

can

fun

the

previous

tutorial

and

save

the

output

VerticalBendingTest.txt

2.

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Or, read the VerticalBendingTest.txt (it runs the tutorial directly)

in

Step 2: Go to Design Optimization 1.

Go to Design Opt> Analysis File> a)

Create

b) Assign… File name is: VerticalBendingTest.txt 2.

Now Go to utility menu and read the VerticalBendingTestOptimization.txt

file (read input) 3.

Go to Design Opt> Design Set>List (choose ALL sets). This gives you the various iterations

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Step 3: Now use this model From this point on you can use this model to perform all other analysis.

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