Combining advanced 3D printing technologies with origami principles: A new paradigm for the design of functional, durable, and scalable springs

Origami has recently emerged as a platform for building functional engineering systems with versatile characteristics that targeted niche applications. One widely utilized origami-based structure is known as the Kresling origami spring (KOS), which inspired, among many other things, the design of vibration isolators, fluidic muscles, and mechanical bit memory switches. KOSs are traditionally constructed out of foldable materials (e.g. paper, kapton, fabric, polyethylene terephthalate, and acetate sheets) using conventional fabrication processes which include manual folding and creasing. Such materials and fabrication methods are ideal for conceptual illustrations and laboratory testing, but lack many important aspects necessary for real-world implementation. In addition to the very low durability resulting from the high plastic deformations at the folds; lack of repeatability, and high variation of performance among similar samples are typically inevitable. To circumvent these issues, this paper presents a novel approach for the design and 3D printing of a KOS which mimics the qualitative behavior of a paper-based KOS without compromising on durability, repeatability, and functionality. In the new design, each fundamental triangle in the traditional KOS is replaced by an inner central rigid core and an outer flexible rubber-like frame, which are fabricated out of different visco-elastic materials using advanced 3D printing technologies. The quasi-static behavior of the fabricated springs is assessed under both compressive and tensile loads. It is shown that KOSs with linear, softening, hardening, mono- and bi-stable restoring force behavior can be fabricated using the proposed design by simple changes to the geometric design parameters. The durability of the resulting springs is also assessed with no changes observed in the quasi-static behavior even after 5000 loading cycles.