PLA Double-Spirals Offering Enhanced Spatial Extensibility

Inspired by natural spiral curves, this study aims to present a strategy to find a compromise between extensibility and load-bearing capacity in structures made from polylactic acid (PLA) as a brittle material. Herein, four geometrically distinct double-spiral modules are fabricated using a three-dimensional (3D) printer and subjected to tension, in-plane sliding, and out-of-plane sliding to assess both their in-plane and out-of-plane mechanical performance. Subsequently, a modular spiral-based metastructure is developed and tested under tension in two different directions. The results show that the maximum extension of the modules under different loading scenarios varies from 9 to 86 mm, while their load-bearing capacity ranges between 18 and 78 N. These significant variations highlight the considerable influence of both geometry and loading conditions on the mechanical behavior of the double-spiral modules. Moreover, the 250% horizontal and 130% vertical extensibility of the metastructure emphasize the importance of the spatial orientation of the modules in determining the efficiency of spiral-based metastructures. This study suggests that double-spirals with adjustable mechanical properties, if designed rationally, can offer a promising strategy to address the limited deformability of materials like PLA, and when arranged in specific spatial configurations, they can contribute to the development of energy-dissipative metastructures with enhanced extensibility.