Cavitation of a spherical body under mechanical and self gravitational forces

TL;DR

This paper investigates the formation of cavities in a self-gravitating, compressible elastic sphere under boundary displacement, providing existence conditions, numerical methods, and insights into how cavity size depends on displacement and density.

Contribution

It introduces a variational framework for cavitation in self-gravitating elastic bodies, including existence criteria and a numerical scheme for approximating minimizers.

Findings

Cavitation occurs at the center for large displacements.

Cavity size increases with boundary displacement.

Numerical simulations illustrate the dependence on density and displacement.

Abstract

In this paper we look for minimizers of the energy functional for isotropic compressible elasticity taking into consideration the effect of a gravitational field induced by the body itself. We consider the displacement problem in which the outer boundary of the body is subjected to a Dirichlet type boundary condition. For a spherically symmetric body occupying the unit ball $\mathcal{B}\in\mathbb{R}^3$, the minimization is done within the class of radially symmetric deformations. We give conditions for the existence of such minimizers, for satisfaction of the Euler--Lagrange equations, and show that for large displacements the minimizer must develop a cavity at the centre. A numerical scheme for approximating these minimizers is given together with some simulations that show the dependence of the cavity radius and minimum energy on the displacement and mass density of the body.