Investigating the Mullins Effect and Energy Dissipation in Magnetorheological Polyurethane Elastomers.

Alex Elías-Zúñiga,Isaac H Jiménez-Cedeño,Luis M Palacios-Pineda,Daniel Olvera-Trejo,Oscar Martínez-Romero,Imperio A Perales-Martínez

doi:10.3390/ijms21155318

Abstract

The aim of this article was to investigate the mechanical performance of magnetorheological polyurethane elastomers reinforced with different concentrations of carbonyl iron microparticles (CIPs) in which stress softening, energy dissipation, residual strains, microparticles orientation, and magnetic flux density effects will be considered. Other aspects, such as the determination of the dissipated energy during cyclic loading and unloading, were investigated by considering a pseudo-elastic network model that takes into account residual strains, magnetic field intensity, and the isotropic and anisotropic material behavior. Theoretical predictions confirmed that the material shear modulus becomes sensitive not only for higher concentrations of CIPs added into the elastomer material matrix, but also to the magnetic flux intensity that induces attractive forces between CIPs and to the strong bonds between these and the elastomer matrix. It was also found that the addition of CIPs when embedded into the polymer matrix with a predefined orientation enhances the material shear modulus as well as its capacity to dissipate energy when subjected to magnetic flux density in loading and unloading directions.

Highlights

The aim of this paper focused on investigating the Mullins effect, residual strains, and energy dissipation in uniaxial loading–unloading cycles by considering the concentration of carbonyl iron particles (CIPs) added into an elastomer matrix, their orientation influence, and the impact of applying a magnetic flux density in the loading direction
Coquelle et al investigated the Mullins effect in Rhodorsil RTV 1062S elastomer reinforced with 10% volume of carbonyl iron particles subjected to cyclic uniaxial extension tests without the application of a magnetic flux density [1]
They found that the Mullins effect, after a few loading–unloading cycles of anisotropic samples, is close to that of the isotropic ones and that the usage of a coupling agent strongly changes the slope of the first traction

Summary

Introduction

The aim of this paper focused on investigating the Mullins effect, residual strains, and energy dissipation in uniaxial loading–unloading cycles by considering the concentration of carbonyl iron particles (CIPs) added into an elastomer matrix, their orientation influence, and the impact of applying a magnetic flux density in the loading direction. Combining small and wide-angle X-ray scattering techniques (SAXS and WAXS), Jiang et al [5] performed in situ experimental measurements of an isotropic copolymer sample BA6500-Fe3O44.9 subjected to a uniaxial loading–unloading cycle They found that during the loading process, the copolymer grafted nanoparticles (magnetite, Fe3O4) were forced to be highly oriented along the tensile direction, revealing strain-hardening behavior because the applied stress is transferred from the copolymer matrix to the oriented Fe3O4 nanoparticles. The energy dissipation factor E is defined in order to quantify the differences among the tested material samples for the various concentrations of CIPs in order to investigate if there exists debonding between the CIPs and the polymer matrix, since a decrease in the material shear modulus is evident after the application of the first loading and unloading cycle

Finite Elasticity

Stress-Softening Model

Comparison with Experimental Data

Numerical Results

Magnetorheological Material Preparation

Conclusions