Defect Production in Compressed Filament Bundles

We discuss the response of biopolymer filament bundles bound by transient cross-linkers to compressive loading. These systems admit a mechanical instability at stresses typically below that of traditional Euler buckling. In this instability, there is thermally activated pair production of topological defects that generate localized regions of bending-kinks. These kinks shorten the bundle's effective length, thereby reducing the elastic energy of the mechanically loaded structure. This effect is the thermal analog of the Schwinger effect, in which a sufficiently large electric field causes electron-positron pair production. We discuss this analogy and describe the implications of this analysis for the mechanics of biopolymer filament bundles of various types under compression.