Lightweight knitted fabric nap-core sandwich: A comprehensive comparison between single sided structure and double sided structure

Abstract

Nap-core sandwich, which is lightweight and characterized by many remarkable properties, comes from an extraordinary combination of sandwich-structured composites and textile materials. However, the application of it in industries is still limited due to a lack of understanding its mechanical properties and behaviors. Several studies based on experimentation or numerical simulation have been conducted to fulfill the shortage, and this study is in the mainstream of exploring how the sandwich composite performs when geometries or materials of the nap-core vary. Namely, the comparison of double sided structure and single sided structure used for the nap-core will be presented in this article. The inquiry derives from the fact that a nap-core can take either of the two structures, but the advantages and disadvantages of each have not been identified yet while manufacturers hardly own costly molds for both. Since only the double sided nap-core is actually available, a modeling method is being deployed in Abaqus engineering software to compare it with an equivalent single sided nap-core that is simulated having the same materials and boundary dimensions. Before that, the Representative Volume Element homogenization method was employed to effectively determine engineering constants of the nap-core’s knitted fabric. The final results reveal that the single sided nap-core has better strength than the double sided nap-core in typical loading cases, but it assumes less smooth stress distribution.