Application of Linear Viscoelastic Continuum Damage Theory to the Low and High Strain Rate Response of Thermoplastic Polyurethane

H Chen,A.R Trivedi,C.R Siviour

doi:10.1007/s11340-020-00608-2

Abstract

BackgroundUnderstanding the mechanical response of elastomers to applied deformation at different strain rates and temperatures is crucial in industrial design and manufacture; however, this response is often difficult to measure, especially at high strain rates (e.g. > 100 s− 1), and more predictive methods to obtain constitutive relationships are required.ObjectiveThe objective of the research described in this paper is to develop such methods.MethodThe paper outlines a novel approach combining quasi-static monotonic tests in tension and compression, quasi-static cyclic tests in tension, and high strain rate tests in compression, with dynamic mechanical analysis and time-temperature superposition. A generalized viscoelastic model incorporating continuum damage is calibrated.ResultsThe results show that a model calibrated using data from quasi-static compression and dynamic mechanical analysis can be used to adequately predict the compressive high strain rate response: hence, this paper provides an important step in the development of a methodology that avoids the requirement to obtain constitutive data from high strain rate experiments. In addition, data from FE models of the dynamic mechanical analysis experiments are provided, along with a discussion of data obtained from tensile and cyclic loading.ConclusionsThe paper demonstrates the effectiveness of ‘indirect’ predictive methods to obtain information about high rate behaviour of low modulus materials.

Highlights

Thermoplastic elastomers are widely used in engineering and industry, e.g. for bumpers, seals, moulded gaskets and ducts, often working as impact and vibration mitigators
The linear viscoelastic properties are first obtained from Dynamic mechanical analysis (DMA) experiments, which are integrated with quasistatic monotonic tests in compression to determine the phenomenological parameters for the damage model
The aim of this project is to investigate the whether the use of linear viscoelastic continuum damage theory in conventional mechanical experiments allows correlation between quasi-static and high strain rate tests

Summary

Introduction

Thermoplastic elastomers are widely used in engineering and industry, e.g. for bumpers, seals, moulded gaskets and ducts, often working as impact and vibration mitigators They benefit from advantageous properties such as flexibility, durability and property recovery after deformation, but simul taneously have dependence on polymer network morphology, temperature, strain rate and loading history [1,2,3,4]. At elevated temperature, the molecular chains have greater mobility owing to increased free volume and energy, and are able to respond on the loading timescale. This dynamic mechanism responds at low loading rates. Understanding the mechanical response of elastomers to applied deformation at different strain rates and temperatures is crucial in industrial design and manufacture; this response is often difficult to measure, especially at high strain rates (e.g. >100 s−1), and more predictive methods to obtain constitutive relationships are required

Methods

Results

Conclusion