Indentation methodologies for extraction of Visco- elastic Characteristics of Polymers

Lead Research Organisation: University of Cambridge
Department Name: Materials Science & Metallurgy


This project will carried out with AWE, the organization is interesting in a new test method for monitoring material properties after extended periods in service and/or exposure to demanding environmental conditions.
SEMPID (Software for the Extraction of Material Properties from Indentation Data) package with evaluation of plasticity parameter and approaches for characterization of creep has been developed by Gorden Laboratory in recent years. This work will extend to explore the potential for interrogating the time-dependent (viscoelastic) properties of polymeric materials (filled, unfilled and foamed) over a range of temperature and strain rate. The development of new approaches to identification of indentation outcomes, iterative (FEM) modelling of the indentation process, evaluation of agreement levels between predicted and observed outcomes, and convergence on best fit combination of property parameter values will be carried out by this project.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R511870/1 01/10/2017 30/09/2023
1937213 Studentship EP/R511870/1 01/10/2017 30/09/2021 YI CUI
Description Rubber; creep; activation energy; finite element analysis; composite
Both elastic stress-strain testing and (primary and secondary) creep testing have been carried out on unreinforced rubber and on two particulate-reinforced rubber composites. This has been done at three different temperatures for all three materials. The stress-strain curve of the rubber conforms well to that expected from classical rubber elasticity theory. When expressed as true stress - true strain relationships, all three materials exhibit approximately linear plots, with the increases in stiffness on adding the particulate conforming to composite elasticity theory. The creep behaviour of all three materials can be captured well using a Miller-Norton formulation and the observed dependence on temperature has been used to estimate the activation energy for creep to be ~7 kJ mole-1. This is thought to indicate that the creep process does not involve rupture of covalent bonds (for the range of applied loads used), but is associated with physical processes such as molecular untangling. The fillers do enhance the creep resistance, to a degree that is broadly consistent with the expected load transfer from matrix to particulate.
Exploitation Route It can be applied for testing and predicting the rubber creep behaviour, which is developing in a different path.
Sectors Aerospace, Defence and Marine,Environment,Healthcare,Manufacturing, including Industrial Biotechology

Description It can be used as test method for the predicting and testing the creep behaviour of rubber and reinforced rubber. It has also given a clear guild that help to develop and manufacture fibres filled reinforced rubbers.
First Year Of Impact 2019
Sector Aerospace, Defence and Marine,Environment,Manufacturing, including Industrial Biotechology
Impact Types Economic