Degradation and healing in a generalized neo-Hookean solid due to infusion of a fluid

TL;DR

This paper investigates how fluid infusion causes degradation and healing in a generalized neo-Hookean solid, affecting its stress response and material properties over time, with applications to polymer composites.

Contribution

It models the effects of fluid diffusion on a generalized neo-Hookean solid, including creep, stress relaxation, and deformation-dependent diffusivity, extending understanding of degradation and healing mechanisms.

Findings

Fluid infusion causes creep and stress relaxation in the solid.

Material properties become time-dependent due to diffusion effects.

Deformation-dependent diffusivity influences the diffusion process.

Abstract

The mechanical response and load bearing capacity of high performance polymer composites changes due to diffusion of a fluid, temperature, oxidation or the extent of the deformation. Hence, there is a need to study the response of bodies under such degradation mechanisms. In this paper, we study the effect of degradation and healing due to the diffusion of a fluid on the response of a solid which prior to the diffusion can be described by the generalized neo-Hookean model. We show that a generalized neo-Hookean solid - which behaves like an elastic body (i.e., it does not produce entropy) within a purely mechanical context - creeps and stress relaxes when infused with a fluid and behaves like a body whose material properties are time dependent. We specifically investigate the torsion of a generalized neo-Hookean circular cylindrical annulus infused with a fluid. The equations of equilibrium for a generalized neo-Hookean solid are solved together with the convection-diffusion equation for the fluid concentration. Different boundary conditions for the fluid concentration are also considered. We also solve the problem for the case when the diffusivity of the fluid depends on the deformation of the generalized neo-Hookean solid.