Bio‐Based Skin and Bones: Hemp CNC‐Knitted and Robotically Wound Material System for Sustainable Membrane Structures

Abstract

This paper introduces a novel bio‐based hybrid material system combining hemp CNC‐knitted textiles with robotically wound hemp‐fiber‐reinforced composites (HFPC) to form an integrated membrane structure. The research builds on two investigations into material grading strategies for architecture. Firstly, through the examination of CNC‐knitted membranes, where differentiated knit properties are calibrated to steer structural performance via yarn and knit structure choices. Secondly, on fiber‐wound bio‐composites, which demonstrate how fiber orientation, winding strategies can replace conventional synthetic or metal supports with lightweight yet performative bio‐based skeletons, while foregrounding circularity and long‐term renewable, CO ₂ ‐neutral materiality.

The paper addresses fabrication challenges inherent to natural fibers, whose heterogeneous and less industrialized qualities require adaptation of robotic coreless filament winding (CFW) and digital knitting processes. By developing workflows capable of accommodating these inconsistencies, the research explores how material variability becomes a design driver, opening perspectives on integrating non‐standardized resources without compromising performance. Focusing on fast‐growing hemp fibers—yarns for knitting and rovings for CFW—the study investigates one of the strongest plant‐based fibers. While weaker than synthetics, hemp's limitations are reframed as opportunities for design exploration rather than constraints.

A research probe demonstrates the hybrid system: a hemp roving‐wound support acting as framework, and a CNC‐knitted hemp skin that both clads and engages with the wound support. Unlike conventional textile membranes dependent on metal or glass‐fiber substructures, this system employs HFPC as the primary load‐bearing framework, offering a materially efficient and organic alternative. The CFW process enables custom geometry and three‐dimensional articulation by distributing filament density in response to structural requirements — reinforcing stress zones while reducing redundancy elsewhere, still providing support. The knitted membrane is tailored through a clustering strategy by using Intarsia technique and simulation analysis for surface subdivision into differentiated yarn types and knit structures. Hemp yarns of varying thickness address local stress requirements, while distinct stitch logics steer textile strain capacity. This heterogeneity allows the knitted skin to actively influence structural performance while expressing the textile's behavior under load.

The research demonstrates that natural fiber bio‐based systems, when strategically coupled and digitally fabricated with input from simulation, can achieve stiffness, flexibility, and spatial and surface expression sufficient to compete with synthetic alternatives by offering novel design solutions and domains of application. By situating this hybrid system within the discourse on sustainable structural membranes, the paper reflects on both the challenges and opportunities of working with anisotropic, weaker yet renewable fiber materials.