Stress-Softening in Particle-Filled Polyurethanes under Cyclic Compressive Loading.

Wenshuai Xu,Yu Liu,Heng Jiang,Hao Zhang,Yuren Wang,Meng Chen,Mangong Zhang

doi:10.3390/polym12071588

Abstract

Elastomer compositions containing various particulate fillers can be formulated according to the specific functions required of them. Stress softening—which is also known as the Mullins effect—occurs during high loading and unloading paths in certain supramolecular elastomer materials. Previous experiments have revealed that the load–displacement response differs according to the filler used, demonstrating an unusual model of correspondence between the constitutive materials. Using a spherical indentation method and numerical simulation, we investigated the Mullins effect on polyurethane (PU) compositions subjected to cyclic uniaxial compressive load. The PU compositions comprised rigid particulate fillers (i.e., nano-silica and carbon black). The neo-Hooke model and the Ogden–Roxburgh Mullins model were used to describe the nonlinear deformation behavior of the soft materials. Based on finite element methods and parameter optimization, the load–displacement curves of various filled PUs were analyzed and fitted, enabling constitutive parameter prediction and inverse modeling. Hence, correspondence relationships between material components and constitutive parameters were established. Such relationships are instructive for the preparation of materials with specific properties. The method described herein is a more quantitative approach to the formulation of elastomer compositions comprising particulate fillers.

Highlights

Mechanical softening promotes energy dissipation and heat buildup in nanoparticle-reinforced elastomers
The toto cyclic uniaxial compressive loading areare shown in Theresponse responsecurves curvesofofthe theNPFPUs
We proposed the inversion parameters neo-Hookeand and Mullins models, we proposed the constitutive inversion constitutive of the UFPUsofand andNPFPUs, obtained and a cyclic loading curve

Summary

Introduction

Mechanical softening promotes energy dissipation and heat buildup in nanoparticle-reinforced elastomers. Such materials are used widely in engineering applications such as vibration reduction, heat preservation, damping improvement, and the development of composite materials [1,2,3]. PUs are similar to natural rubber in terms of mechanical hysteresis, residual strain, and the stress-softening effect, and they have many excellent properties such as strong designability, good environmental adaptability, favorable damping characteristics, and biocompatibility [6,7,8,9,10,11]. When subjected to cyclic uniaxial loading, rubber-like materials exhibit an irreversible degradation in mechanical properties following the initial load, resulting in an obvious difference between the loading and unloading paths. The stress required to achieve a certain elongation for the first time is always greater than the reloading stress

Methods

Discussion

Conclusion