Origin of Unusually High Rigidity in Selected Helical Coil Structures

Using continuum elasticity theory, we describe the elastic behavior of helical coils with an asymmetric double-helix structure and identify conditions, under which they become very rigid. Theoretical insight gained for macro-structures including a stretched telephone cord and an unsupported helical staircase is universal and of interest for the elastic behavior of helical structures on the micro- and nanometer scale.