Programming tension in 3D-printed networks inspired by spiderwebs

Abstract

Each element in tensioned structural networks—e.g., tensegrity or architectural fabrics—requires a specific tension to achieve the desired shape and stability. These structures are challenging to manufacture, 3D print, or assemble because flattening them during fabrication introduces multiplicative inaccuracies in the final tension gradients. We overcome this challenge by offering an algorithm for direct 3D printing of such networks with programmed tension gradients, analogous to the spinning of spiderwebs. The algorithm: (i) defines the desired network and prescribes its tension gradients; (ii) converts it into an unstretched counterpart by optimizing element lengths and converting straight elements into arcs; and (iii) decomposes the network into printable toolpaths; with the option to: (iv) flatten curved 2/3D networks to ensure printing compatibility; and (v) automatically resolve unwanted crossings introduced by flattening. Experimental validation is achieved using 2D unit cells with <1.0 % strain error in the tension gradients. The method remains effective for networks with a minimum element length of 5.8 mm and a maximum stress of 7.3 MPa. Fabricating complex cases is demonstrated for flat spiderweb, curved mesh, and tensegrity networks. The method represents a stepping-stone toward developing compact, integrated cable networks and orthotic devices with programmable moment-exerting structures.