Discrete and non-local elastica

• The buckling and post-buckling behavior of an elastic lattice system referred to as the discrete elastica problem is investigated.
• This discrete physical model is also mathematically equivalent to a finite difference formulation of the continuum elastica.
• A continualization method is applied for approximating the difference operators by differential ones.
• It is shown that the non-local continuum exactly fits the discrete system, both in the buckling and the post-buckling ranges.
• An asymptotic expansion is performed for approximating the post-buckling branches of the discrete model.

In this paper, the buckling and post-buckling behavior of an elastic lattice system referred to as the discrete elastica problem is investigated using an equivalent non-local continuum approach. The geometrically exact post-buckling analysis of the elastic chain, also called Hencky system, is first numerically solved using the shooting method. This discrete physical model is also mathematically equivalent to a finite difference formulation of the continuum elastica. Starting from the exact difference equations of the discrete problem, a continualization method is applied for approximating the difference operators by differential ones, in order to better characterize the discrete system by an enriched continuous one. It is shown that the new continuum associated with the discrete system exactly fits the discrete elastica post-buckling problem, where the non-locality is of Eringen׳s type (also called stress gradient non-local model). An asymptotic expansion is performed for both the discrete and the non-local continuum models, in order to approximate the post-buckling branches of the discrete system. Some numerical investigations show the efficiency of the non-local approach, especially for capturing the scale effects inherent to the cell size of the lattice model.