Tough but lightweight engineering structures with superior impact resistance

An international team of researchers, led by Changfang Zhao, from Nanjing University of Science and Technology, has developed a novel lightweight, high toughness auxetic structure made from plastic composite laminates. The auxetic structure can be used for constructing primary structures in the transport industry, such as land vehicles, as well as aircrafts and marine vessels, to maximize fuel efficiency.

Auxetic structure made from plastic composite laminate

Normal structures or materials exhibit the usual phenomenon when stretched (compressed), i.e. they become thinner (thicker) in the direction perpendicular to the applied load. Auxetics refer to structures or materials that exhibits an unusual behaviour when mechanical loaded. When stretched (compressed), they become thicker (thinner) perpendicular to the applied force. They can exhibit this behaviour because of their particular (engineered) internal structure. In the form of a material, we say that the auxetic exhibits negative Poisson’s Ratio. More importantly, the auxetic exhibits robust shock absorbing properties and this lend to wide applicability, such as armour, vehicle bumper, aircraft body, hull of a marine vessel and in packaging.

However, making the auxetic lightweight, tough with sufficiently stiffened components could be even more attractive as it endows the auxetic with multi-functional applications, for instance as a primary structure for electric vehicles, including aircrafts and marine vessels, demands that these be made using lightweight materials for high power efficiency, that can also deliver maximum protection to the vehicle and passengers in the event of a collision.

Changfang Zhao and his team designed and fabricated 'cell structures', i.e. small scale version of the auxetic structure as shown in the figure, using laminated carbon fiber reinforced plastics (CFRP), which is the same material used in the Boeing 787 aircraft fuselage. The cell structures were subjected to compressive loading in three orthogonal directions to evaluate for the effectiveness of energy absorption by the respective direction. Using a state-of-the-art digital correlation imaging system to observe the deformation of the cell structure, they concluded that the cell structures were capable of auxetic behaviour in two orthogonal directions and possesses high energy-absorbing capacity in the third direction. Future design of CFRP auxetic structures as light-weight primary structures will be able to leverage the directional dependent properties for both structural support and impact resistance.

The members of his team of international researchers are hailed from Nanjing University of Science and Technology (comprising Jianlin Zhong, Kebin Zhang, Zhendong Zhang, Jie Ren, Guigao Le), National University of Singapore (Heow Pueh Lee) and Newcastle University (Kheng Lim Goh).

The work has been published in Composite Structures (https://doi.org/10.1016/j.compstruct.2022.115667). For further details and enquiry on potential collaboration, please contact Changfang Zhao at [email protected], or Kheng Lim Goh at [email protected].

Published: 05 Jun 2022

Contact details:

Dr Kheng Lim Goh

172A Ang Mo Kio Avenue 8 #05-01
SIT Building @ Nanyang Polytechnic
Singapore 567739

+65 6908 6073
News topics: 
Academic discipline: 
Content type: 
Reference: 

Composite Structures, Volume 292, 15 July 2022, 115667, https://doi.org/10.1016/j.compstruct.2022.115667

Funding information:

This work was financially supported by the National Natural Science Foundation of China (12002169, 11902160), the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX21_0342), and the 2021 Excellent Doctor Training Fund of Nanjing University of Science and Technology. Especially, the China Scholarship Council (202106840033) was acknowledged, which sponsored the first author (Changfang Zhao) as a visiting student at the National University of Singapore for studying one year. Besides, we were also acknowledged the assistance in manufacture and experiment from Taizihe District Zhongke Carbon Fiber Composites Business Center and XTOP 3D Technology (Shenzhen) Co., Ltd.