PUBLIC demand for safe sea transportation is increasing
which aims to reduce the risk of loss of human life by
minimizing the damage caused by collisions with other ships
or collisions with docks [1]. Efforts to prevent and anticipate
collisions to prevent damage or leakage to ships by designing
safe structures. Thus it is important to design reliable safety
components by evaluating the response of the hull structure
using the crashworthiness method on the ship structure.
Therefore, in designing the construction of a ship, it should be
equipped with safety components such as fenders. Fenders are
bumpers that are used to reduce collisions that occur when a
ship is about to dock at a dock or when a ship is moored and is
rocked by the port's waves or currents. Fenders with high
energy absorption and low reaction force are typically capable
of damping [2]. Fenders are typically constructed of rubber,
elastomeric foam, or plastic. The type of fender used is
determined by a number of factors, including the ship's size
and weight, the maximum allowable stand-off, the ship's
structure, tide variations, and other site-specific conditions.
The size of the fender is determined by the energy of the ship
at anchor, which is related to the berthing accuracy.
Meanwhile, aluminum foam is a porous metal material with a
cellular structure and a spherical shape, with closed pores
accounting for more than 70% of the total volume [3].
Because of its high energy absorption capacity and low
specific gravity, this material has been used in the automotive
industry (acoustics and vibration dampers), the aerospace
industry as a structural component in turbines, the naval
industry as a low frequency vibration damper, and the marine
industry [4],[5],[6]. The fender stucture is presented in Figure
1.
Figure 1. Fender Stucture
Previous numerical analysis and experiments demonstrated
that the crashworthiness of the structures could be improved
by using advanced materials or optimizing their shape
configurations. In recent years, there has been a great deal of
Optimization of ship fender under axial load using Taguchi
FAUZAN DJAMALUDDIN
Departmen of Mechanical Engineering, Hasanuddin University, Makassar, INDONESIA.
Abstract: Aluminum foam is one of the materials that can be used to support the ship's fender structure to
withstand impact loads. The purpose of this study was to analyze the absorption capacity of conventional fender
designs with fender designs using aluminum foam. In analyzing the energy absorption of each fender variation,
the crashworthiness test is used. Crashworthiness was applied with the help of Abaqus CAE software to design
the fender frame and perform loading simulations. The aluminum material used is aluminum alloy 6061 with
specifications and consists of fender frames and aluminum foam frames. To obtain optimal parameter values,
fender shape analysis will be carried out using the Taguchi method on Minitab software. Meanwhile, to
determine the contribution of the parameters to the TEA (Total Energy Absorption) response using the One-
Way Anova (Analysis of Variance) method on Minitab. In conclusion, the simulation of Aluminum Foam
proved to have high absorption.
Keywords: fender, foam, ship, optimization, taguchi
Received: June 18, 2021. Revised: June 28, 2022. Accepted: July 25, 2022. Published: September 21, 2022.
1. Introduction
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research into the latter. Resechers [7] improved the designs of
cylindrical shells in order to increase crushing energy.
The purpose of this research is to determine the optimization
values of different type of foam-filled ship fenders using
Taguchi Method.
Specific energy absorption (SEA) is always an indicator of a
structure's energy absorbing capability in crashworthiness
design and should be set as one objective function. The SEA
is commonly defined as
SEA = TEA / 𝑚 (1)
However, because this expression does not account for the
hitter's intrusion, this article adopts a more
feasible expression, as suggested by [8].
SEA = Energy Absorbed / (Structural weight × ∆𝑙) (2)
where ∆𝑙 denotes the hitter's crushing distance Eq. (2) is
derived from the fact that structures with high
energyabsorbing capacity are generally associated with short
crushing distances. Overly large impact forces transmitted to
the hull structures during ship berthing may cause wreck
damage. As a result, peak crushing force (Pm) is set
as another objective function that should be kept low [9].
The Taguchi Experiment Design is a systematic evaluation of
two or more parameters on the ability to influence the average
outcome variable with the stages of problem identification,
determining goals, determining measurement methods,
identifying factors, identifying control and noise factors,
determining the level of each factor, measuring results. In
determining the level of the number of degrees of freedom
using an orthogonal array (orthogonal matrix). Orthogonal
array is a matrix of factors and levels where the elements
of the matrix are arranged according to rows and columns.
T standard orthogonal array is presented in Table 1.
Similarly, the orthogonal array notation is:
𝐿𝑛(𝑙𝑓) (3)
Where: f = number of column factors l = many levels n =
number of observations (rows) L = orthogonal design.
TABLE 1. Standard orthogonal array
To obtain optimum strength, this study employs a
computerized simulation method with the assistance of
Abaqus software. This computerized simulation is carried
out by modeling the Abaqus from the beam test object
model and varying the cross-sectional model. The first stage
of the research involves simulating axial loads in order to
determine the best cross-section to absorb impact energy.
ABAQUS is the software used to analyze specimens under
axial loading. The specimen material is aluminum alloy
6061, the mechanical properties of which are shown in Table
2. Finite element analysis used to determine the best energy
absorption with different cross section.
TABLE 2. Mechanical Properties of Aluminium Alloy 6061
[4] (Pirmohammad & Sarvani, 2018)
The energy absorption of fenders with conventional models
and fenders with the addition of aluminum foam will be
investigated in this study. The preparation of specimens
begins with the creation of components in the Abaqus
software. According to Figure 2 , three components have
been created, each with a different shape. In addition, the top
section serves as a load, and the bottom section serves as a
rigid. Aluminum Alloy 6061 was used, with a specimen
thickness of 8 mm. The load is attached to the top side of the
fender via the top section. The loading type specified is a
static load with a pressure category. The mesh size on the
tube surface is set to 5mm.
FIGURE 2. Cross-sectional image of fender with Aluminum
Foam (FF) , Conventional Fender (FK) and Fender Double
With Foam (FDF)
2. Method and Material
2.1 Crashworthiness Optimization
Problem Definition
2.2 Optimizing Using Taguchi Method
2.3 Material Specification
3. Results and Discussion
3.1 Variation in Cross-section
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FIGURE 3. Axial Loading Simulation results
Fenders with variations in the shape of the inner cross section
are analyzed by simulation. From the simulation results, it can
be seen that the visual deformation after axial loading
(Figure 3). The loading stroke moves each fender at a rate of
15.6m/s. It can be seen that FF can absorb more energy
because of friction between foam and outer fender [10],
[11]. This variation has a higher maximum absorption
value than other types of fenders (Table 3).
TABLE 3. Energy absorption parameters on the fender with
variations in the shape of the inner section
Excel using the interpolation method before being entered
into the taguchi. The cross section type and displacement,
which consists of three displacement values, are the
factors used (800 mm, 100mm and 5mm). The number of
factor and level is presented in Table 4.
TABLE 4. Number of Factor & Level
After determining the factor and level, enter the response
value, which includes the force and Total Energy
Absorption values. Which then yields the SNR or Signal
To Ratio and Means results as shown below (Table 5).
TABLE 5. Results of Taguchi Method
The cross-sectional shape of each variation of fender and
displacement is shown on the graph plot as the factors and
levels that affect the difference in energy absorption of each
variation. Factors influence the response as a result of these
differences, where the response value is the TEA (Total
Energy Absorption) value. The data can then be analyzed
using the Mean of Means Plot graph, which is a graph of the
average data obtained from the three tests. Because the highest
energy absorption value is desired in this case, the fender with
a variation of FDF and a displacement of 800mm has the best
value.
FIGURE 4 Main Effects Plot
Meanwhile, the Main Effects Plot for SN Ratios is a graph that
shows the ratio that influences the response; in other
words, the larger the signal value and the smaller the noise
value, the better. According to the graph plot results, the
variation of the FDF fender has the highest SNR value. As a
result, the FDF variation is the best. Lastly, the main effect
plot and the main effects plot For SN Ratios are presented in
Figure 4 and Figure 5 respectively.
3.2 Axial Loading Simulation Results
From the table above The total absorption energy can be
calculated by adding the total suppression force for each
displacement on the fender specimen. The FF variation
fender has the highest total absorption energy value, with an
absorption value of 464.1346 J. While FDF has 302,9572 J
of TEA. The FK variation fender, with a total absorption
energy of 187.7471 J, is a fender variation with a very low
total absorption energy when compared to other
crosssectional shapes. This is consistent with the theory that
closed cavity foams, particularly Al-alloy foams, exhibit
constant stress and can absorb more energy than solid
aluminum. During impact application, this foam exhibits a
pressure elastic response. Another advantage of aluminum
foam is that the majority of the absorbed energy cannot
be converted into plastic deformation energy [10],[11].
3.3 Optimizing Using Taguchi Method
The Taguchi method is carried out starting from the planning
process by involving as few resources as possible, setting the
variation of factors, the level of penetration to get a response
as an ingredient in determining the optimal combination.
The following are the steps in the Taguchi method
optimization process. The optimization process begins with
the factor and level data being normalized in Microsoft
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Based on Table 6 method's decision-making procedure, if
P-Value < 𝛼 then H0 = b1 = b2 =..... = b, then there is no
treatment effect, and if P-Value ≧ 𝛼 then H1 b1 b2 …..b, then
there is an effect of changing the treatment on the response.
The results above show that the P-Value value is 0.668,
which is greater than the value of, implying that the value of
the entered variable has an effect on the response by
changing the treatment.
In the future work, this simulation and optimization results
will be validated with experimental results of foam-filled
fender under axial load.
The FF cross-sectional model has the highest Total Energy
Absorption value of 464.1346 J, while the FK cross-
sectional model has the lowest Total Energy Absorption
value of 187.7471 J. The optimum value is owned by the
cross-sectional shape of the FDF based on the optimization
process using the Taguchi method with different responses
in Total Energy Absorption (TEA). And based on the
optimization results, the addition of Aluminium Foam to the
ship's fender has been shown to help absorb energy.
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FIGURE 5. Main Effects Plot For SN Ratios
3.4 One-Way ANOVA
The displacement values entered in the test of the effect on
the response are the variables included in the test of the
effect on the response, and the response values entered are
the Total Energy Absorption (TEA) and Force values. The
analysis of the contribution of factors to the response yielded
the following results:
TABLE 6. Analysis Variance results
5. Conclusion
References
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Acknowledgements
We gratefully thanks the Head of the Vibrations Laboratory
of Hasanuddin University who has facilitated the data
collection process.
Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting Policy)
The author(s) contributed in the present research, at all
stages from the formulation of the problem to the
final findings and solution.
Sources of Funding for Research Presented in a Scientific
Article or Scientific Article Itself
No funding was received for conducting this study.
Conflict of Interest
The author(s) declare no potential conflicts of interest
concerning the research, authorship, or publication of this
article.
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