Elastogranular columns and beams

• Published in: Soft matter Vol. 18; no. 43; pp. 8262 - 827
• Main Authors: Guerra, Arman, Lautzenhiser, Casey, Jiang, Xin, Flanagan, Kate, Rak, David, Tibbits, Skylar, Holmes, Douglas P
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 09.11.2022
• Subjects: Arches; Cantilever beams; Chains; Fabrication; Jamming; Mechanical properties; Prestressing; Reusable components; Stiffness; Strings
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/d2sm01010k

String and grains can be combined to create structures capable of bearing significant loads. In this work, we prepare columns and beams through a layer-by-layer deposition of granular matter and loops of fiber strings, and characterize their mechanical properties. The loops cause the grains to jam, and the inter-grain contact leads to a Hertzian-like constitutive response. Initially, one force chain that propagates vertically through the column bears most of the compressive load. As the magnitude of the load is increased, more force chains form in the column, which act in parallel to increase its stiffness, akin to a "super-Hertzian" regime. Applying a compressive prestress enables the structures to withstand shear, enabling the fabrication of cantilevered beams. This work provides a mechanical framework to use elastogranular jamming to create rapid, reusable infrastructure components, such as columns, beams, and arches from inexpensive, commonplace materials, such as rocks and string. Columns and beams, prepared from only rocks and string, can bear significant loads, enabling the formation of reusable and adaptable structures.