“…Assuming everything remains two-dimensional, we describe the position of the plate in terms of arc length s at time t: (X(s, t), Z(s, t)). Denoting the local stress resultant by (N X , N Z ), the equations of motion of the ruck, where it is lifted off the plane, are [1,19] where κ is the local curvature. The moment and curvature are related by M = Bκ, where B is the bending stiffness.…”