Jamming of straight filaments without boundaries

Granular jamming is generally associated with external confinement, but some examples of cohesive filamentous structures, such as bird nests and spun yarn, challenge that notion. Our recent work revealed micromechanic origins of basic bulk responses to compression in packed, flexible filaments with friction. Here, we aim to identify a minimal packing protocol for achieving a rigid state reminiscent of bird-built cup-nests, in which frictional contacts prevent the release of frustrated internal stresses. Analysis of plasticity in the spinning of yarn, and preliminary experimental data, will be used to shed light on the phenomenon.