Negative Poisson's ratio structure (NPRS) is a special kind of material that has been extensively studied for its ability to absorb impact energy effectively. It has the potential to be used for protecting lives during collisions, such as in an unfortunate car accident on the road. To tackle the challenge of making NPRS lightweight, e.g. for meeting electric vehicle's energy efficiency, the researchers discussed the basic concepts of NPRS and how it can be made using a specific type of strong and lightweight material called laminated carbon fiber reinforced plastics (CFRP). They also used a method called finite element analysis (FEA) to study the mechanical behavior of the CFRP-NPRS. Additionally, they explored the future applications and development of CFRP-NPRS for lightweight cushioning and energy absorption. The study found that the CFRP-NPRS may experience cracking, delamination, and shear fracture near the corners, and a closed structure may undergo deformation. When the opening structure and closed structure are combined, the closed structure plays a more significant role in the deformation. The NPRS property of CFRP-NPRS is observed through inward contraction of the cross-beam. The stress on the beams shows an alternating distribution pattern, and the layer of fibers called the 0-fiber layer mainly carries the load.
The study was led by Dr. Zhao Chang Fang, a talented young researcher who has recently completed his PhD study from Nanjing University of Science and Technology in China, and who was a visiting scholar at Newcastle University Singapore (Jan 2022 to Mar 2023) and National University of Singapore (Oct 2021-Oct 2022). Dr Zhao is moving to Tsing Hwa University to do his post-doctoral training. The team's findings have been published in Materials Today Proceedings.