Lightweight Design of High-speed Train under the Development of
New Materials
Ying Lei
1, a
1
School of mechanical engineering, Xi'an Traffic Engineering Institute, Shaanxi Xi'an 710300, China
Keywords: New materials, high-speed speed, magnesium alloy.
Abstract: With the development of society and economy, the transportation demand of the railway market is
constantly improving, as an important part of railway transportation; high-speed train can meet the
transportation needs of long distance, large volume and high density. Compared with the automotive and
aerospace industries, the development of lightweight materials of high-speed train is relatively rare, but its
role cannot be ignored, the lightweight design of high-speed train is an integral part of the research on high-
speed train technology at present, it is an important condition for realizing fast, efficient, safe and
convenient transportation of high-speed train. With the continuous development of high-speed train
technology, high-speed motor train requires more lightweight materials. This paper has carried out some
research on the new materials used in high-speed train, in order to provide a certain references for the
lightweight design of high-speed train.
1 INTRODUCTION
High-speed train is a kind of train that can
continuously run at high speed, its maximum speed
is generally above 200km/h. High-speed train
belongs to modern high-speed vehicles, which
embodies the train's top science and technology; it
can greatly improve the train travel speed and
improve the train transportation efficiency. High-
speed train is fast, comfortable, stable and safe,
energy-saving and environmentally friendly, which
is very popular among the people, many countries in
the world strongly support the use of new high-
speed trains to meet the growing travel demand. On
October 1, 1964, the world's first high-speed train
was opened in Japan, its maximum speed is nearly
440 kilometers, since then, many countries have
begun to build high-speed railways, and the speed of
trains has continued to increase. High-speed train in
China commonly refer to d-series high-speed train
that started after the sixth railway speed increase on
April 18, 2007, its maximum speed reaches 350
kilometers per hour. For example, the high-speed
train that runs from Beijing to Shanghai takes only
five hours, the high-speed train is an important
means of transporting that connects cities and plays
an important role in the economic development of
the city.
(Zi Bingtao, Wang Hui, 2014) The weight of a
high-speed train can cause line loss, energy
consumption, and cause load on the brake system.
At present, the speed of high-speed train is generally
more than 200 kilometers per hour, and its impact on
the track is much larger than that of ordinary trains;
in addition to a certain kinetic energy, the train must
overcome various frictional forces when moving.
When the speed of a high-speed train exceeds 200
kilometers per hour, it requires several times kinetic
energy of an ordinary train, and the resistance to be
overcome is more than ten times that of a normal
train. Since the weight requirement of high-speed
train is stricter than that of ordinary trains, it also
requires high power and high performance; therefore,
high-speed train is equipped with equipment that is
not available in ordinary trains, such as streamlined
cones and equipment compartments, etc., this will
inevitably lead to an increase in weight. Therefore,
lightweight design is the key technology of high-
speed train, which is related to the success or failure
of high-speed train development. This paper focuses
on the application of magnesium alloy, a new
lightweight material, in the design of high-speed
train.
Lei, Y.
Lightweight Design of High-speed Train under the Development of New Materials.
DOI: 10.5220/0008865102170221
In Proceedings of 5th International Conference on Vehicle, Mechanical and Electrical Engineering (ICVMEE 2019), pages 217-221
ISBN: 978-989-758-412-1
Copyright
c
2020 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
217
2 CHARACTERISTICS AND
APPLICATION OF
MAGNESIUM ALLOY
2.1 Characteristics of Magnesium
Alloy
Magnesium alloy has many characteristics: light
weight, good rigidity, certain corrosion resistance
and dimensional stability, impact resistance, wear
resistance, good attenuation and easy recovery; in
addition, it has high heat conduction and electric
conduction, non-magnetic, good shielding and non-
toxic characteristics. Although the proportion of
magnesium alloy is heavier than plastic, the strength
and elasticity per unit weight are higher than those
of plastic, therefore, under the condition of
components and parts with the same strength, the
components and parts of magnesium alloy can be
made thinner and lighter than plastic. In addition,
since the specific strength of the magnesium alloy is
also higher than that of the aluminum alloy and the
iron, the weight of the aluminum or iron component
can be reduced without reducing the strength of the
component. The relative strength (ratio of strength
and mass) of magnesium alloy is the highest. The
specific stiffness (ratio of stiffness and mass) is
close to that of aluminum alloy and steel; it is much
higher than engineering plastics. In the elastic range,
when the magnesium alloy is subjected to the impact
load, the absorbed energy is larger than aluminum
alloy, so the magnesium alloy has good seismic and
noise reduction performance. Figure.1 and Figure.2
show the comparison of magnesium alloy with other
materials, Table.1 shows the comparison of physical
properties of magnesium and aluminum.
Fig 1. Comparison of specific stiffness between magnesium alloy and other metal materials.
Fig 2. Comparison of specific strength between magnesium alloy and other metal materials.
ICVMEE 2019 - 5th International Conference on Vehicle, Mechanical and Electrical Engineering
218
Table 1. Comparison of physical properties of magnesium
and aluminum.
item
magnesium
aluminum
atomic weight
12
13
density 20g/cm3
1.74
2.7
melting point
650
660
specific heat KJ/m3
1.03
0.9
latent heat of
melting KJ/kg
368
397
coefficient of heat
conductivity W/M.K
154
220
coefficient of
thermal
expansion×10-6
25.2
23.6
2.2 Application of Magnesium Alloy
(Zhang Kaihan, 2009) Magnesium alloy has low
density and it is the lightest metal structural material
in practical application, which has the advantages of
high specific strength and specific stiffness, good
electromagnetic shielding effect, strong seismic
shock absorption capability, easy to shape and easy
recycling, it has broad application prospects and
great application potential in the fields of aviation,
aerospace, automotive, 3C products and military
industry., which has caused governments,
enterprises and research institutions in many
countries to attach great importance to magnesium
alloy and its forming technology, invested a lot of
manpower and financial resources for development
research, and achieved certain results. As "green,
environmental protection, sustainable" become the
main theme of world development, magnesium alloy,
which is characterized by light weight and
recyclable use, is increasingly becoming ideal
materials for modern industrial products, and its
market demand has also shown a steady growth
trend. The development of modern technology and
related industrial technologies, the promotion of
magnesium alloy applications in various countries
not only eliminates people's doubts about the use of
magnesium alloy, but also makes their unique
advantages more perfect, the scope of application is
rapidly expanding, and make the market
development of this emerging material extremely
optimistic.
3 APPLICATION RESEARCH OF
MAGNESIUM ALLOY IN HIGH-
SPEED TRAIN
3.1 Mechanical Properties of
Magnesium Alloy
Magnesium alloy is a high-strength metal material;
the strength of magnesium alloy is only lower than
that of high-strength steel and titanium alloy in
metal, which is higher than most engineering
plastics. Table.2 is the comparison of mechanical
properties between commonly used magnesium
Table 2. Comparison of mechanical properties of commonly used magnesium alloys and aluminum alloys commonly used
in trains.
Mg-alloys
AZ31B
H112
280-320
94
95-97
92
14-21
AZ80
T5
350
72
ZK60
T6
365-410
94
11-15
Mg-Zn-Y-Zr
T6
356
93
7
AZ91
O
331
80
12
5083
H111
275-350
90
93
12-15
5083
0
298
100
23.0
5083
H321
305
91
22.5
6005A
T6
250-270
75
6-8
6061
T6
290
75
64
84
12
Al
-alloys
6082
T6
290-310
78
67
83
8-10
6082
T4
260
93
18.8
7005
T6
340-350
71
8
7N01
T5
345
84
82
7018
T79
350
95
11
7020
T6
395
77
78
12
Lightweight Design of High-speed Train under the Development of New Materials
219
alloy and aluminum alloy in trains. Magnesium alloy
is a shaped metal; it can withstand a certain degree
of deformation at normal temperature before
breaking, so that the safety of the equipment can be
guaranteed. Table.3 shows the research results of the
strain rate affecting the bending strength and the
deformation amount. The results show that the
magnesium alloy presents a plastic state under high-
speed impact. The data in Table.2 and Table.3 shows
that the plastically processed magnesium alloy has
very strong strength and plasticity.
(Li Wei, et.al, 2016) Note: αW/BMIG--MIG
welded joint strength and base material strength ratio,
αW/BTIG--TIG welded joint strength and base
material strength ratio, αW/BFSW-FSW welded
joint strength and base material strength ratio.
Table 3. Effect of strain rate on mechanical properties of
(EM Cast) and (Extruded) AZ31.
Strain
rate 1/s
EM Cast
Extruded
a
Fl/10-
3m
σwb/MPa
Fl/10-
3m
5.6E-04
321 9.3
9.3
518.3
9.6
2.0E+02
494
6.0
555
4.8
3.2 Welding Properties of Magnesium
Alloy
(Zhou Jianle, Wang Jun, 2000) When the
magnesium alloy material is applied to a car body
structure of a high-speed train, it necessarily
involves welding technology. A large number of
magnesium alloy welding tests have proved that
magnesium alloy have good weldability, and solid
state welding methods can achieve better joint
performance. Through the successfully developed
magnesium alloy ventilating window and
magnesium alloy sleeper, it is proved that the
equipment manufacturing technology of magnesium
alloy has been mature, the welding of the ventilating
window frame is completed by TIG method, and the
frame of sleeper is welded by cemented composite
method.
3.3 Damping and Sound Insulation
Performance of Magnesium Alloy
Magnesium alloy has good damping and sound
insulation properties. Research on the damping of
magnesium alloys has shown that magnesium alloy
has excellent properties of high strength and high
damping, and they can play a good role in important
parts of high-speed train. Magnesium alloy
composite structure has better application prospects,
such as magnesium alloy composite panel,
magnesium alloy honeycomb panel, (Zhi Deyu,
1999) magnesium alloy honeycomb panel has
excellent sound insulation performance, it is mainly
used for high-speed floor, roof, door and other parts
of high-speed train, it has excellent sound insulation
performance, the study proves that the strongest
noise inside the rail train is around 2000Hz, but the
magnesium alloy honeycomb panel still has strong
sound insulation ability at this frequency. Table.3
shows the mechanical properties test results of an
AZ31B magnesium alloy panel, it can be seen that
the ordinary magnesium alloy plate has a normal
mechanical performance index not lower than that of
the aluminum alloy plate.
Figure 3. Comparison of sound insulation of honeycomb
panels with different heights.
Table 4. Properties of AZ31B wide magnesium alloypanel
(thickness is 1.45mm, width is 1450mm, length is greater
than 4500mm).
Orientation
Rp0.2/MPa
Rm/MPa
A/%
RD
207
291
21.5
45°
242
299
24.8
TD
265
310
24.5
3.4 Research on Magnesium Alloy
Processing Technology for High-
Speed Train
The technology of magnesium alloy is mainly used
in the production of various parts in train, which are
generally completed by pressure casting, extrusion
and rolling, this production technology is now
mature. Magnesium alloys used in the manufacture
of high-speed train require large-size magnesium
ICVMEE 2019 - 5th International Conference on Vehicle, Mechanical and Electrical Engineering
220
alloy bars and high-efficiency welding techniques
and equipment, as well as anti-corrosion technology.
Moreover, the reliability study of magnesium alloy
is also indispensable. The magnesium alloy
processing technology and equipment developed at
present are the basis for the manufacture of
magnesium alloy high-speed motor trains, based on
this, the body of the magnesium alloy high-speed
motor car and the manufacturing technology of the
whole vehicle will become a reality.
3.5 Benefit Prediction of Magnesium
Alloy Material in High-Speed Train
Lightweight Design
As a new material for making high-speed train,
magnesium alloy has many uncertainties in its
application technology; however, with the
development manufacturing technology of
magnesium alloy material, the application of
magnesium alloy in high-speed train will be more
and more. By then, the benefits of lightweight
design of magnesium alloy materials will be an
advantage. The application of magnesium alloy in
the automotive industry has produced good energy-
saving effects. This is a good example: in the weight
of a car, every 100 kg of mass is reduced, gasoline
can be reduced by 0.3 L/Km, and CO2 gas emissions
can be reduced by 63 g/ Km. This paper predicts the
benefits of magnesium alloy materials in the
lightweight design of high-speed train. The strength
of the magnesium alloy above is similar to that of
the existing aluminum alloy used in trains. However,
the elastic modulus of the magnesium alloy is 45
GPa, and the elastic modulus of the aluminum alloy
is 70 GPa. We must not only ensure the strength but
also the rigidity and both are indispensable. The
thickness ratio and mass ratio of the two materials
can be seen in the following formula:
𝒕
𝑴𝒈
/𝒕
𝑨𝒍
=
√
𝑬
𝑨𝒍
/𝑬
𝑴𝒈
𝟑
𝑚
𝑀𝑔
/𝑚
𝐴𝑙
=(𝑑
𝑀𝑔
/𝑑
𝐴𝑙
)
√
𝐸
𝐴𝑙
/𝐸
𝑀𝑔
3
E and d represent the elastic and density modulus,
respectively, in the formula. In the formula, the
thickness ratio is 1.16 and the mass ratio is 0.772. In
summary, when the same strength and rigidity are
ensured, the weight of the magnesium alloy body is
32.8% lower than that of the aluminum alloy car
body. If the weight of the single-section aluminum
alloy car body is 10 tons, the weight of the single-
section magnesium alloy car body is 6.72 tons.
Taking China's CRH3 train eight-car as an example,
the aluminum alloy body is about 420 tons, the
magnesium alloy body is about 394 tons, and the
weight is reduced by 9.38%. In addition, when the
running speed of the motor car is relatively low, the
energy saving effect brought by weight reduction is
more obvious than that of the train at high speed.
When the high-speed runs at 200km/H, the energy
consumption per unit mileage can be reduced by
9.16%.
5 CONCLUSION
Magnesium alloy material is used in the manufacture
of high-speed train, it is necessary to establish a
comprehensive and scientific design idea. From the
perspective of mechanical properties, processing and
casting, resource utilization, manufacturing cost and
safety, magnesium alloy has the potential to become
new material of high-speed motor train, and it can
provide a good foundation for lightweight design of
high-speed train.
REFERENCES
Li Wei, Liu Jun bird, Liu Danxun, Lei Lisong. Analysis of
the Application of New Materials and Structures in the
Lightweight Process of Car Body, the 13th Henan
Automotive Engineering Science and Technology
Symposium, October 17, 2016.
Zhang Kaihan. Discussion on the Application of New
Materials in Railway Vehicles [J], China High-tech
Enterprise, 2009 (9), 9-10.
Zhi Deyu. Some Ways of Lightweight Automotive
Materials [J], Automotive Technology and Materials,
1999, (6), 1-4.
Zhou Jianle, Wang Jun. Design of Aluminum Alloy Body
for Metro Vehicles, Urban Mass Transit, 2000(2): 53-
56.
Zi Bingtao, Wang Hui. Magnesium Alloy and Its
Applications in Industry [J], Chinese Journal of Rare
Metals, 2004, 28(1), 229-232.
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221