SIZE OPTIMIZATION DESIGN OF THREEWHEELED MOTORCYCLE FRAME WITH CARGO BOX

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International Journal of Mechanical Engineering and Technology (IJMET)
Volume 10, Issue 05, May 2019, pp. 345-356, Article ID: IJMET_10_05_036
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=5
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
SIZE OPTIMIZATION DESIGN OF THREE-
WHEELED MOTORCYCLE FRAME WITH
CARGO BOX
Seung Jun Na
Department of Mechanical Engineering, Graduate School, Kongju National University, Korea
Seung Yeon Kim
Department of Mechanical and Electric Engineering, Graduate School, Kongju National
University, Korea
Euy Sik Jeon
Department of Mechanical Engineering, Graduate School (Industrial Technology Research
Institute), Kongju National University, Korea
ABSTRACT
A size optimization design method for the frame of a three-wheeled motorcycle
with a cargo box is proposed considering high load and motion conditions that may
occur under straight-driving and curve-driving conditions. The existing frame of a
three-wheeled motorcycle with a cargo box was compared with the frame under high
load through finite-element analysis by applying longitudinal bending and torsion,
and the thicknesses of the members that exceeded allowable stress were optimized
using the design of experiments. The comparison and analysis of both the existing
model and the optimally designed model confirmed that the frame strength was
improved compared with the existing frame.
Key words: Three-wheeled Motorcycle Frame, Size Optimization, High load, DOE
Cite this Article: Seung Jun Na, Seung Yeon Kim, Euy Sik Jeon, Size Optimization
Design of Three-Wheeled Motorcycle Frame with Cargo Box, International Journal
of Mechanical Engineering and Technology 10(5), 2019, pp. 345-356.
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=5
1. INTRODUCTION
The Korean Road Traffic Act defines motorcycles as two-wheeled vehicles. Motorcycles
generally are two-wheeled vehicles with small-sized gasoline engines or with motors.
Recently, with design changes for various applications, three-wheeled and four-wheeled types
have also been included in the definition of motorcycles [1]
.
A motorcycle consists of a power system, a brake system, a steering system, a frame, and
convenience devices. Among them, the frame must be able to fix each component, endure the
load of the driver and cargo as well as the load that may arise during driving, and secure safe

Seung Jun Na, Seung Yeon Kim, Euy Sik Jeon
driving performance. To meet such structural requirements, the frame must secure strength on
a sufficient level and satisfy functional requirements for various applications and designs.
Therefore, continuous research and development have been conducted.
Lim and Jeon [2]
estimated the driving safety of each three-wheeled motorcycle type by
examining overseas driving safety assessment measures and using specifications, as well as
the height of the center of gravity. They fabricated a three-wheeled motorcycle for
verification, examined the changes in driving safety according to the tread changes, and
performed verification through an actual vehicle test. Bhunte and Deshmukh [3]
proposed a
method for predicting fatigue life using the analysis on static and dynamic loads for the wheel
fork frame. Lee et al. [4]
performed three-dimensional (3D) modeling of the motorcycle frame,
selected design elements required to increase the frame stiffness, and then conducted a design
parameter analysis to assess the stiffness according to the parameter changes. Zhang et al. [5]
proposed a method for assessing the fatigue life of the motorcycle frame using road driving
test results and finite-element analysis. In addition, Bocciolone et al. [6]
compared the
experimental results on the static stiffness and natural vibration characteristics of the
motorcycle frame with the analysis results.
In this study, the deformation and stress of the existing frame of a three-wheeled
motorcycle with a cargo box were compared with those of the frame under high load through
finite-element analysis by applying longitudinal bending and torsion. After selecting the
design elements required for improving the strength of the frame members that exceeded
allowable stress, the sizes of the members were optimized using the design of experiments
(DOE). [7~12]
The optimally designed model was compared with the existing model through
finite-element analysis to verify its validity.
2. STRUCTURAL ANALYSIS OF THE FRAME OF A THREE-
WHEELED MOTORCYCLE WITH A CARGO BOX
In this study, after the finite-element modeling of the frame of a three-wheeled motorcycle
with a cargo box was performed, and structural analysis was conducted for the existing frame
and the frame under high load based on the analysis conditions that considered an actual
driving environment.
2.1. Definition of the frame of a three-wheeled motorcycle with a cargo box
Three-wheeled motorcycles in South Korea refer to vehicles with three or more wheels among
the two-wheeled vehicles defined in the Vehicle Management Law [13, 14]
, and the maximum
load weight is equal to or less than 100 kg. These are classified as other types. Figure 1 shows
a three-wheeled motorcycle with a cargo box. It is composed of tubes, brackets,
reinforcements, and a support frame.

Size Optimization Design of Three-Wheeled Motorcycle Frame with Cargo Box
Figure 1. Structure of three-wheeled motorcycle with cargo box
2.2. Structural analysis model and conditions for the frame of a three-wheeled
motorcycle with a cargo box
Figure 2 shows the finite-element model for the structural analysis of the frame of a three-
wheeled motorcycle with a cargo box. The details of the model are summarized in Table 1,2.
Hyper Works was used for finite-element analysis, and the finite-element model used the shell
elements.
Figure 2. Finite element model
Table 1 Material of three-wheeled motorcycle frame
Material
Yield Stress
[MPa]
Young's
Modulus
[MPa]
Poisson's Ratio
Density
[kg/mm3
]
Structural
Steel
250 210,000 0.3 7.8×10-6

Table 2 Finite element model input condition
Mesh type Mesh size Element
Tetragon 5mm Pshell
As shown in Figure 3, the loading and boundary conditions applied to the frame of a
three-wheeled motorcycle with a cargo box were determined considering the weight of the
driver and cargo as well as motion conditions that may occur under straight-driving and
curve-driving conditions, and the front and rear wheels were modeled using rigid elements.
Emergency braking condition characteristics were reflected by longitudinal bending, whereas
the conditions that may occur during quick turning movement were reflected by torsion. The
longitudinal bending and torsional loading conditions can be generalized by restraining the
displacement of the rear wheel in all directions and by applying a load to the center of the
front wheel.
Figure 3. Fixation and load condition of structure
2.3. Structural analysis results of the frame of a three-wheeled motorcycle with a
cargo box and comparative analysis
Structural analysis was conducted by applying the loading and boundary conditions of the
frame of a three-wheeled motorcycle with a cargo box, as shown in Figure.3.
Figure.4 shows the structural analysis results for each loading condition, and Table 3
presents a comparison of the maximum displacement and stress that occur at the center of
front wheels.

(a) Longitudinal Bending
(b) Torsion
(c) Longitudinal Bending (High Load)
(d) Torsion (High Load)
Figure 4 Structural analysis results

Table 3 Simulation analysis results
Load Condition
Results
Displacement
(mm)
Stress
(MPa)
Longitudinal
Bending
1.322 210.3
Torsion 1.729 246.6
Longitudinal Bending
(High Load)
4.626 297.7
Torsion
(High Load)
11.53 357
3. SIZE OPTIMIZATION FOR THE FRAME OF A THREE-WHEELED
MOTORCYCLE WITH A CARGO BOX
To increase the frame strength of a three-wheeled motorcycle with a cargo box that can
endure high load as well as the load that may occur under straight-driving and curve-driving
conditions, parameters for design change were set by comparing the structural analysis results
of the existing model with those of the model under high load. A size optimization design was
performed for comparison with the basic model under high load in terms of strength.
3.1. Design parameter setting and range determination
The frame strength of a three-wheeled motorcycle with a cargo box heavily depends on the
design parameters of the members connected to the center of the front wheels. As shown in
Figure 5, three members-under tube, bottom top tube, and bracket-were selected, and design
parameter analysis conditions were set, as shown in Table 4.
Figure 5. Design variables
Table 4 Level and design variables
Level 1
[ ] 2
[ ] 3
[ ]
1 1.8 3.2 3.0
2 2.4 3.8 3.5
3 3.0 4.4 4.0
3.2. DOE
In this study, computational tests were conducted using central composite design (CCD), as
shown in Table 5. Based on the data obtained from the tests, DOE was performed using
Minitab 17, which is a statistics software.

Table 5 Different types proposed by DOE [results]
No 1
[ ] 2
[ ] 3
[ ]
Disp.
[ ]
Stress
[MPa]
1 3.2 1.8 3.0 11.53 357
2 3.8 1.8 3.5 10.22 298.4
3 3.2 2.4 3.5 9.517 263.9
4 3.8 2.4 3.5 8.865 262.3
5 3.8 2.4 3.5 8.865 262.3
6 3.2 3.0 3.0 8.595 253.2
7 3.8 2.4 4.0 8.752 245.3
8 4.4 1.8 4.0 9.453 273.4
9 4.4 3.0 4.0 7.394 218.8
10 3.2 1.8 4.0 10.85 283.2
11 3.8 3.0 3.5 7.931 234.4
12 3.8 2.4 3.5 8.865 262.3
13 3.8 2.4 3.0 8.996 283.0
14 3.8 2.4 3.5 8.865 262.3
15 3.2 3.0 4.0 8.417 219.4
16 3.8 2.4 3.5 8.865 262.3
17 4.4 3.0 3.0 7.591 251.7
18 4.4 1.8 3.0 9.795 317.5
19 3.8 2.4 3.5 8.865 262.3
20 4.4 2.4 3.5 8.354 259.7
Figure 6 shows the residual graph for confirming suitability. From the result of the
analysis of variance for the stress and displacement of the three members, the P-value was
0.068 or less, confirming the significance accordingly. It was confirmed that the experiment
results were accurate, because the R-sq value representing the accuracy of the experiment was
97.24% for stress and 99.40% for displacement. Equation (1) is the regression equation of the
response according to the results of the analysis of variance.
Displacement ( )
( ) ( )
( )
(1)
Stress ( )
( ) ( ) ( )

Figure 6. Residual graph
3.3. Size optimization results and analysis
The response optimization tool of Minitab was used to derive optimization conditions. As
shown in Figure 7, the analysis of the main effect of the frame strength improvement revealed
that all design parameters affected frame damage according to the loading conditions. In
particular, the thickness of the bracket had the largest influence.

Figure 7. Main effects plot
As shown in Figure 8, the optimized thickness was 2.5520 mm for the bottom top tube,
4.40 mm for the under tube, and 3.5026 mm for the bracket.
Figure 8. Optimization conditions

Figure 9 shows the analysis results derived through a finite-element analysis after a model
was created based on the optimization results derived through CCD. Table 6 shows the
comparison of finite-element analysis results of the existing model under high load with those
of the size-optimized model.
(a) Displacement analysis of optimization model
(b) Stress analysis of optimization model
Figure 9. Analysis of optimization model
Table 6 Results of the optimization
Solution
Results
Existing model Optimum model
Displacement
(mm)
11.53 7.919
Stress
(MPa)
357 239.8

4. CONCLUSION
In this study, a size optimization design was performed to improve frame strength using the
3D design model of the frame of a three-wheeled motorcycle with a cargo box, and the
following results were obtained. The loading and boundary conditions for the frame of a
three-wheeled motorcycle with a cargo box were constructed considering the weight of the
driver and cargo, as well as the motion conditions that may occur under straight-driving and
curve-driving conditions.
Emergency braking condition characteristics were reflected by longitudinal bending,
while the conditions that may occur during quick turning movement were reflected by torsion.
Structural analysis was conducted for the basic model and the basic model under high load,
and the maximum displacement and the frame stress occurring at the center of the front
wheels were obtained and compared. To improve the strength of the frame of a three-wheeled
motorcycle with a cargo box, the structural analysis results for the basic model under high
load were analyzed, design parameters for design change were set, and size optimization
design was performed for a comparison with the basic model under high load in terms of
strength. Increasing the thickness of the bracket through size optimization had the largest
influence on improving the longitudinal bending and torsional strength of the frame of a
three-wheeled motorcycle with a cargo box under high load.
REFERENCES
[1] Industrial Competitiveness of Motorcycle, Marketing Forum, DacoD&S, Seoul, 2007.
[2] J.H. Lim, Y.D. Jeon, "A Study on the Driving Stability Performance of Motorcycle with
three wheels", KSAE, Volume 24, No.5, Pages 1420-1424, 2014.
[3] G. V. Bhunte and T. R. Deshmukh, “A Review on Design and Analysis of Two Wheeler
Chassis,” International Journal for Research in Emerging Science and Technology,
Volume 2, No.1, pp.42-45, 2015.
[4] Y.W. Lee, S.Y. Ha, J.H. Kwon, “Parametric Analysis for Structural Stiffness
Enhancement of Motorcycle Frame”, KSAE, Volume 24, No.5, Pages 612-617, 2016
[5] L. Zhang, C. Lu and K. Tieu, “Fatigue Analysis of a Motorcycle Frame System Based on
a Road Test and the Finite Element Method”, Materials Science Forum, Volumes 773-
774, pp.850-858, 2014.
[6] M. Bocciolone, F. Cheli, M. Pezzola and R. Vigano, “Static and Dynamic Properties of a
Motorcycle Frame: Experimental and Numerical Motorcycle Frame: Experimental and
Numerical Approach”, WIT Transactions on Modelling and Simulation, Volume 41,
pp.517-526, 2005.
[7] M.F. Hassanein, A.A. Elkawas, "Shear analysis and design of high-strength steel
corrugated web girders for bridge design", Engineering Structures, Volume 146, 1
September 2017, Pages 18-33.
[8] Y.C. Kim, Jung Kie Hong, “Lightweight Crane Design by Using Topology and Shape
Optimization”, KSME-A.2011.35.7.821, pp. 821~826, 2011.
[9] W.G. Lee, Jung Seok Kim, “Lightweight Design of Brake Bracket for Composite Bogie
Using Topology Optimization“, Trans. Korean Soc. Mech. Eng. A, 2015, Vol. 39, No. 3,
pp. 283~289.
[10] M. Hatami, M.C.M. Cuijpers, M.D Boot, “Experimental optimization of the vanes
geometry for a variable”, Energy Conversion and Management, Volume 106, December
2015, Pages1057~1077.

[11] Y.J. Song, “Optimal Design of Lightweight Seat Extension Equipment Using Topology
Optimization and Design of Experiment”, IJAER, 2017, Vol. 12, No. 9, pp. 1855~1859.
[12] Y.S. Kim, “Optimization of process variables for improvement of seat-backboard peel
strength using response surface design method”, JMST, December 2017, Vol. 31, Issue 12,
pp. 5915~5920.
[13] Republic of Korea Law, "Automobile Control Law", Article 3 (Types of Cars)
[14] Ministry of Land, Infrastructure and Transport Law, "Enforcement Regulation of
Automobile Control Law" Article 2 (Classification of Cars)

SIZE OPTIMIZATION DESIGN OF THREEWHEELED MOTORCYCLE FRAME WITH CARGO BOX

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