The manufacture and characterization of composite three-dimensional re-entrant auxetic cellular structures made from carbon fiber reinforced polymer

In recent years, three-dimensional auxetic structures have attracted great interest. Generally, three-dimensional auxetic structures are of complicate geometries which make them difficult to fabricate, benefiting from the development of additive manufacturing technologies, many three-dimensional auxetic structures can be made from metals or polymers. However, to the authors' knowledge, the additive manufacturing technology of fiber reinforced polymer is not fully developed, and none three-dimensional auxetic structure made from fiber reinforced polymer has been reported before. To integrate the high specific stiffness, high specific strength, and light weight merits of high-performance fiber reinforced polymer composites into three-dimensional auxetic structures with unique properties, research on composite three-dimensional auxetic structures made from fiber reinforced polymer should be conducted. This paper presents the composite three-dimensional re-entrant auxetic structures made from carbon fiber reinforced polymer laminates using an interlocking assembly method. The auxetic nature of the composite structure has been verified by experimental testing and finite element simulations. Based on the finite element models, the dependences of the Poisson's ratio and effective compression modulus of the composite auxetic three-dimensional re-entrant structure on the re-entrant angle have been studied and compared to metal three-dimensional re-entrant structure. A comparative study of the Poisson's ratio and specific stiffness of carbon fiber reinforced polymer composite auxetic structure with the three-dimensional printed polymer and metal auxetic structures in literature has also been conducted.