The document summarizes a structural analysis and optimization of a mountain bike frame. The analysis was conducted using ANSYS software to determine the frame's behavior under static loads, perform natural frequency analysis, and study the effects of different materials (aluminum, titanium, carbon fiber) and rider weights. The initial analysis found high stresses and displacements at certain points. To address this, the frame geometry was optimized by adding small supporting tubes to critical failure areas. The optimized frame showed improvements like reduced maximum stress and displacement values across all materials. In conclusion, the structural behavior of the mountain bike frame under loading conditions was characterized, and the frame design was improved through optimization to strengthen weak points identified in the analysis.

1. • The Optimization was create
due to the critical area as in
the ANSYS analysis where it
at the chain stay tube and top
tube.
• Hollow tube size about 7mm
radius and 2mm thickness
created at the chain stay tube
and between the top tube
and seat tube
The project objectives are :
• To determine the structural behaviour of the mountain
bike frame using static load.
• To perform natural frequency analysis on the mountain
bike frame and to study the mode shape behaviour.
• To distinguish the effect of the size, frame analysis in
weight of the rider and in different material.
• To optimize and improve the existing geometry of the
frame design to overcome the critical failure part based
on structural and frequency analysis.
OBJECTIVES
ABSTRACT
MUHAMMAD ZULHILMI SHAH BIN ZAFARIN
Bachelor of Engineering (Hons) Mechanical (EM220)
Faculty of Mechanical Engineering
2013257052
Advisor: Dr Kausalyah A/P Venkatosan
Structure Analysis of a Mountain Bike Frame
(Cross Country Frame)
PROJECT METHODOLOGY
Research study
Literature review
Measurement & Collect Data
on the frame
Design process (Using CATIA)
Analysis
Maximum Stress , Maximum Displacement
And Mode Shape Frequency
Optimization
Modified On Critical Part
Result and Conclusion
Commonly, Structural analysis is the pattern of the effects of loads on physical structures and their components part. The mountain bicycle frame is the subject in this structural
analysis in frequency case solution. The structure consists of standard diamond-shape cross-country frame that purpose to use in trail and off-road used. The structural analysis is tested to
the frame to ensure that a structure will satisfied its intended function in variety loads environment. This enquiry leads us to identify the type of failure occurs in the design in term of different
material use. The frequencies in different material also affect the amount of deformation. This mode shape of frequency will be determined in the ANSYS software in terms of frequency
response. Aluminum, titanium and carbon fiber are the tested material that be used in this analysis. Analysis will be computed with the different mass of the rider from 60kg until 150kg of
loads. The analysis result for the frame will be comparing to each material and will be optimize. So, the analysis will obtained the maximum stress, displacement and the mode shape of the
natural frequency throughout the analysis.
Throughout the history of bicycle, there have been
constant improvements in design of cycle frame on
technologies. Most improvements through the years have
been modifications to layout of the mechanisms on the
bicycle. This includes overall shape of the cycle, design of
a frame structure, and material improvements. So, this
structural analysis result could determine the behavior of
the mountain bike frame using static load, perform natural
frequency analysis on the mountain bike frame and to
study the mode shape behavior and optimize the existing
geometry of the frames design to overcome the critical
failure part based on structural and frequency analysis.
INTRODUCTION
CONCLUSIONSBike Geometry
PROJECT METHODOLOGY
Total
deformati
on
1 2 3 4 5 6 7 8 9 10
Before
(mm)
43.5 52.6 68.6 55.5 53.8 146.8 129.2 135.1 206.4 196.9
After (mm) 42.6 51.9 49.6 52.6 74.0 136.9 91.7 103.7 120.6 183.3
Load
(N)
Aluminium Titanium Carbon Fiber
Max
Displace
ment,
(mm)
Before
Max
Displace
ment,
(mm)
After
Max
Displace
ment,
(mm)
Before
Max
Displace
ment,
(mm)
After
Max
Displace
ment,
(mm)
Before
Max
Displace
ment,
(mm)
After
600 0.053 0.0505 0.036 0.0349 0.030 0.0292
1000 0.087 0.0842 0.060 0.0582 0.051 0.0486
1500 0.131 0.1263 0.091 0.0873 0.076 0.0729
Load
(N)
Aluminium Titanium Carbon Fiber
Max
Stress
(Mpa)
Before
Max
Stress
(Mpa)
After
Max
Stress
(Mpa)
Before
Max
Stress
(Mpa)
After
Max
Stress
(Mpa)
Before
Max
Stress,
(Mpa)
After
600 8.602 8.4022 8.639 8.492 8.717 8.661
1000 14.337 14.004 14.399 14.153 14.528 14.433
1500 21.505 21.006 21.598 21.229 21.792 21.650
• Before
Optimization
(a) (b)
(a) (b) (c)
• After
Optimization
Letter Geometry Size S
A Head Tube Angle 690
B Head Tube Length 100.0 mm
C Top Tube Length 575.0 mm
D Stand Over Height 728.9 mm
E Bottom Bracket Offset -44.0 mm
F Bottom Bracket Height 307.5 mm
G Wheel Base 1075.2 mm
H Bottom Bracket Center to top tube 315.8 mm
I Bottom Bracket To Top Seat Tube 390 mm
J Seat Angle 73.00
K Chainstay 427.0 mm
L Reach 398.1 mm
M Stack 578.6 mm
RESULTS AND DISCUSSIONS
Figure 2 After Optimization Frame , (a) 3D view (b) Support at chain stay tube (c) Support at top tube
Figure 1 Before Optimization Frame (a) Max Stress (b) Max Displacement
1) Maximum Stress value
2) Maximum Displacement value
3) Mode Shape Frequency
• Maximum Stress Analysis
The maximum stress occur on the frame is for the carbon
fiber is highest where 21.8 Mpa compare to Titanium and
Aluminium. The higher the stress value of the material, the
shorter time of material tend to fail.
• Maximum Displacement
Aluminium is the highest displacement between other
materials. The value represent the flexible characteristic
causes by the tendency to displace.
• Mode Shape frequency
Mode shape response used to determined fatigue life and
dynamic comfort for the rider to ride a bike. Carbon Fiber
has the higher density and the material is stiff.
In conclusion, the structural behaviour of the mountain bike frame is been able to
find by using static structure load test conduct in the ANSYS software. The static
structure test use to determine the maximum stress occurs in the frame where the
highest stress value occur on Aluminium material. Then, the natural frequency also
gain in 10 various mode shape behaviour where the highest frequency is Carbon
Fiber. Furthermore, the analysis proof that the small size frame can carried different
weight even the maximum mass for all material. The effect can be seen in various
amounts of stress and the displacement on the structure. After that, when regained
all values of the data that need to be modified, then the optimizing are take place.
The frame are been improvise using the existing geometry and shape by adding on
some small support tubing changes into the critical failure part. So, the carbon fiber
display the best mechanical behaviour for the mountain frame. Somehow, even the
small amount of changes in the mountain bike frame could change the values for
the frame give different amount of output.