Design and fabrication of carbon fiber lattices using 3D weaving.

We present a method of designing and fabricating 3D carbon fiber lattices. The lattice design and fabrication is based on crocheting and sewing techniques, where carbon fiber tow is woven through two parallel carbon fiber grids and reinforced with vertical carbon fiber tubes. Compression testing is then performed on three different designs, and these results are compared to other similar lattice structures, finding that the lattices perform similarly to comparable lattices. Finite element analysis is also performed to validate the experimental findings, and provides some insight into the experimental results. The process presented here allows for more design flexibility than other current methods. For example, within a single lattice, different density weave patterns can be used to address specific load requirements. Though fabricated manually here, this process can also be automated for large scale production. With this design flexibility, simplified fabrication, and high strength, the lattices proposed here offer an advantage as compared to similar existing structures.

Fractal-inspired soft deployable structure: a theoretical study.

The study of soft deployable structures is an emergent field that is highly correlated with metamaterial design, soft robotics, medical devices, etc. This paper studies a novel two-dimensional (2D) soft deployable structure that has a fractal layout with hierarchically coupled thin walls, which buckles upon actuation and deforms into a "peacock tail" pattern that is over 10 fold its original dimension. Large deflection theory and finite-element (FE) modeling are used to characterize its mechanical performance and to investigate its potential application in multiple fields. Further, 2D FE homogenization is implemented to extend the novel design into an active plane lattice metamaterial, on which parametric studies are carried out to explore its effective stiffness and large strain properties. The results show that, besides excellent deformability, the "peacock tail" soft deployable structure and its lattice metamaterial derivates exhibit intriguing properties such as multi-stiffening, strong anisotropy, zero/negative Poisson's ratio, a unique post-buckling collapse mechanism, etc. Three-dimensional generalization of the fractal compliant system is modeled to elaborate on the practical use of the structures. This paper aims to enrich the spectrum of soft deployable structures, shedding light on the research of novel soft robots, hierarchical structures, and metamaterials.