Additive Manufacturing and Characterization of Three-dimensional Anepectic Structures

• Autor(a) principal: Catatão, Gonçalo Miguel Rodrigues
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/134774
• topic: Anepectic; Auxetic; Negative Coefficient of Thermal Expansion; Negative Poisson's Ratio; Additive Manufacturing; 3D Structures; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

In recent years there has been an increase of interest in 3D anepectic structures. An anepectic structure is a metamaterial with auxetic behaviour (Negative Poisson's Ratio (NPR)) and negative coefficient of thermal expansion (CTE). This work intends to manufacture and characterize a 3D anepectic structure using materials with positive CTE. A known auxetic structure was used, in which a second material was incorporated to obtain a negative CTE. To achieve the design used in this work, mechanical and thermal finite element simulations were performed to preview the thermomechanical behaviour. The 3D anepectic structures were produced by additive manufacturing using polyvinyl alcohol and Nylon. Two models with different designs were developed. Its characterization necessitated the development of new methodologies to determine the Poisson's ratio (PR) and CTE. One of the models obtained the intended anepectic behaviour. Furthermore, there was a correlation between PR values and the number of cells in the structure. Until this day, this is the first published report of a manufactured and characterized 3D anepectic structure, making this work innovative in the area of metamaterials.