# Rate-independent evolution of sets

## TL;DR

This paper analyzes a mathematical model for the rate-independent evolution of sets with finite perimeter, focusing on adhesive and brittle cases, proving existence of solutions and illustrating properties with numerical examples.

## Contribution

It introduces a new framework for modeling rate-independent set evolution, proving existence of solutions in the adhesive case and exploring properties in the brittle case.

## Key findings

- Existence of energetic solutions in the adhesive case.
- Stability condition satisfied in the brittle case.
- Numerical examples illustrating brittle evolution properties.

## Abstract

The goal of this work is to analyze a model for the rate-independent evolution of sets with finite perimeter. The evolution of the admissible sets is driven by that of a given time-dependent set, which has to include the admissible sets and hence is to be understood as an external loading. The process is driven by the competition between perimeter minimization and minimization of volume changes. \par In the mathematical modeling of this process, we distinguish the adhesive case, in which the constraint that the (complement of) the `external load' contains the evolving sets is penalized by a term contributing to the driving energy functional, from the brittle case, enforcing this constraint. The existence of Energetic solutions for the adhesive system is proved by passing to the limit in the associated time-incremental minimization scheme. In the brittle case, this time-discretization procedure gives rise to evolving sets satisfying the stability condition, but it remains an open problem to additionally deduce energy-dissipation balance in the time-continuous limit. This can be obtained under some suitable quantification of data. The properties of the brittle evolution law are illustrated by numerical examples in two space dimensions.