“…Starting from Haringx work on instability [3], several researchers have studied the lateral motion of helical springs. Analytical solutions have been obtained using equivalent beams under large displacements, [4] [5], but these models cannot manage coil contacts. On the other end, the dynamics of the wire has been addressed by many authors using numerical methods: finite element [6], transfer matrix method [7], finite difference [8], dynamic stiffness matrix method [9].…”