Solution strategies for 1D elastic continuum with long-range interactions: Smooth and fractional decay

An elastic continuum model with long-range forces is addressed in this study within the context of approximate analytical methods. Such a model stems from a mechanically-based approach to non-local theory where long-range central forces are introduced between non-adjacent volume elements. Specifically, long-range forces depend on the relative displacement, on the volume product between interacting elements and they are proportional to a proper, material-dependent, distance-decaying function. Smooth-decay functions lead to integro-differential governing equations whereas hypersingular, fractional- decay functions lead to a fractional differential governing equation of Marchaud type. In this paper the Galerkin and the Rayleigh–Ritz method are used to build approximate solutions to the integro-differential and the fractional differential governing equations. Numerical applications show the accuracy of the proposed approximate solutions as compared to the finite difference approximation and to the fractional finite difference approximation.