Lightweight is one of the core technologies to realize energy saving, to improve the
safety and driving performance of vehicles, and to provide added passenger comfort
as well. It is of special significance for increasing cruising range of electric or
hybrid-powered vehicles. Beyond these, lightweight components use less mass and hence
reduce the primary energy requirement imbedded in the component. Therefore, lightweight
has always been a central topic and an important direction in the automotive field
whether in the past or in the future.
Lightweight promotes the increasing application of lightweight materials, such as
advanced high-strength steels, Al and Mg alloys, carbon fiber-reinforced polymers,
and hybrid metal–polymer composites, which requires innovative forming and joining
processes to produce and assemble automotive components. The concept of the right
material in the right place breeds multi-material car body, and philosophy is more
needed than in the past to balance the maximal weight reduction, service performance,
and cost of vehicles and to comprehensively employ lightweight materials, lightweight
design strategies as well as lightweight processes.
We hope this special issue will promote technological progress in automotive lightweight.
Two articles address how to represent lightweight design by innovative forming processes
and seek to address a hot issue in sheet metal forming; three articles are related
to hybrid or dissimilar materials joining technologies; two articles deal with structural
designs of lightweight electric vehicles; one article proposes an index to quantitatively
evaluate the degree of automotive lightweight; and one article introduces and investigates
lightweight materials, i.e., metal–FRP composites.
The successful publication of this special issue is inseparable from the support of
many parties in this difficult time of Coronavirus pandemic. First of all, we would
like to deeply thank the authors for sharing their latest and excellent research results
and timely submitting their original and revised manuscripts. We are indebted to the
involved reviewers for their time and suggestive review comments that definitely increased
the overall quality of the papers. China Automotive Lightweight Technology Innovation
Strategic Alliance (CALA) is gratefully acknowledged due to the support in collecting
manuscripts and in the organization of the international symposium dedicated to this
special issue. Finally, we are grateful to the colleagues from the editorial office
for providing numerous help and suggestions without reservations during the organization
and production of this special issue.
Highlights of Articles in the Special Issue
The paper “Lightweight in Automotive Components by Forming Technology” by Stephan
Rosenthal, Fabian Maaß, Mike Kamaliev, Marlon Hahn, Soeren Gies, and A. Erman Tekkaya
[Paper No. 1] gives a comprehensive review on the forming processes producing light
automotive components/structures and discusses innovative processes in terms of the
following classification of lightweight design: material, structure, and system lightweight
design.
Yong Sun, Vladimir Luzin, Yixin Duan, Rameshkumar Varma, Lei Shi, and Matthias Weiss,
by composing “Forming-Induced Residual Stress and Material Properties of Roll-Formed
High-Strength Steels” [Paper No. 2], present an experimental and numerical study on
residual stresses of roll-formed high-strength martensitic steel, and the variation
of mechanical properties of a roll-formed automotive part is discussed.
Mingfeng Li, Yanjun Wang, Zhen Niu, and Shanglu Yang, the authors of “Study on the
Weld-Bonding Process Optimization and Mechanical Performance of Aluminum Alloy Joints”
[Paper No. 3], optimize the hybrid weldbonding process to achieve superior weld nugget
quality and more stable mechanical properties of Al alloy joints.
In “Effects of Standoff Distance on Magnetic Pulse Welded Joints Between Aluminum
and Steel Elements in Automobile Body” [Paper No. 4], Junjia Cui, Shaoluo Wang, Wei
Yuan, and Guangyao Li present a novel joining process of dissimilar sheet metals through
magnetic pulse welding, and the correlation between interfacial microstructure and
mechanical performance of joints is revealed.
Yunwu Ma, Sizhe Niu, He Shan, Yongbing Li, and Ninshu Ma, in writing “Impact of Stack
Orientation on Self-Piercing Riveted and Friction Self-Piercing Riveted Aluminum Alloy
and Magnesium Alloy Joints” [Paper No. 5], compare two riveting processes in detail
when joining dissimilar light alloys. It is found there is a preference in stack orientation
of the two dissimilar sheet metals.
Dengfeng Wang, Chong Xie, Yuchang Liu, Wenchao Xu, and Qi Chen composed “Multi-objective
Collaborative Optimization for the Lightweight Design of an Electric Bus Body Frame”
[Paper No. 6], achieving lightweight effect of an electric bus through multi-objective
collaborative lightweight design, where structural strength, stiffness, modal, and
rollover safety of the electric bus are comprehensively considered.
Zitong Shi, Guanhua Chen, Lingxiao Zhu, Jie Li, and Yong Xia, authors of “Sandwich
Structure Design of a Cooling Fin for Battery Modules Against Impact Loads” [Paper
No. 7], numerically and experimentally investigate the mechanical behavior of a lithium-ion
battery module under impact load and propose a design of protection structure utilizing
the energy absorbing ability of cooling fins.
Jun Li, Ligang Wang, Yunxia Chen, Hongzhou Lu, and Haitao Jiang, in “Research and
Application of Lightweight Index for Passenger Cars” [Paper No. 8], introduce an lightweight
index to assess the lightweight level and verify it through statistical analysis on
thousands of internal combustion engine vehicles and battery electric vehicles.
The last paper comes from Ye Lin, Junying Min, Hao Teng, Jianping Lin, Jiahao Hu,
and Nanjie Xu. In “Flexural Performance of Steel–FRP Composites for Automotive Applications”
[Paper No. 9], they comprehensively review the application of metal–FRP composites,
especially in automotive industry, and investigate the mechanical performance of steel–FRP
composites fabricating from steel and various fiber-reinforced polymers subject to
three-point bending.
Dr. A. Erman Tekkaya
Dr. Junying Min
