DIT PhD Project
Supervisor name & contact details:
Name
Email
Prof Steve Jerrams
stephen.jerrams@dit.ie
Supervisors Profile:
Research Centre:
Centre for Elastomer Research (CER)
The Centre for Elastomer Research has the
unique capability of producing reliable
viscoelastic data for characterising the multiaxial physical properties of elastomers. Current
research interests are: Hyperelastic and
Viscoelastic Material Behaviour including
Elastomer Fatigue, Stress Softening and Stress
Relaxation; Biomedical Applications; Advanced
Foams; Swelling Phenomenon.
w: www.dit.ie/cer
Research Centre website:
http://www.dit.ie/researchandenterprise/ditrd
centres/cer/
Supervisors Publication List:
http://arrow.dit.ie/cer/
Title of the Project: The influence of swelling on the fatigue properties of smart elastomers.
Project Summary: All rubbers swell to some degree in oil and this can have serious implications
for the integrity and performance of rubber components in a range of applications (e.g.
automotive parts). Research into non-strain crystallising rubbers swollen in oil has shown that
fatigue life decreases significantly as swelling increases. Reduction in fatigue resistance in all
rubbers is accompanied by a fall in the complex elastic modulus of the material, but this fall is
more pronounced in swollen rubbers. The changes in mechanical properties and lower fatigue
lives of the swollen specimens can be attributed to a number of physical and chemical factors.
Physical factors include the presence of larger voids in the network and a lower initial complex
modulus due to swelling. Chemical factors include changes in the network structure due to oil
swelling, where the number of cross-links resisting the tensile force may be significantly reduced
or where the swelling leads to differences in the equilibrium length of individual chains. Also,
possibly the reformation of polysulphidic linkages during loading cycles is inhibited in the
presence of oil.
There is a burgeoning interest in a range of novel smart elastomers, particularly
magnetorheological elastomers (MREs), but very little research has been carried out into
assessing the dynamic properties of these materials. MREs comprise ferromagnetic particles in a
rubber matrix and their stiffness can be changed instantaneously and reversibly in the presence
of a magnetic field. Hence, they have great potential to be used in damping, vibration isolation
and sealing applications. A research programme is underway to determine the fatigue resilience
of MREs. However, there has been no investigation of the influence of swelling on the dynamic
properties of the material to date. A research project is proposed to fabricate a range of MREs
and subject them to varying degrees of swelling. Thereafter, a series of equi-biaxial fatigue tests
will be carried out to determine fatigue life and establish the parameters that influence fatigue
resistance for the swollen samples. Fracture surfaces will be studied using scanning electron
microscopy (SEM). It will be important to determine if ‘interfacial layers’ between the
ferromagnetic particles and the rubber matrices contribute to fatigue failure by acting as stress
raisers. Hence, the central research question posed is:- Can the fatigue life of a
magnetorheological elastomer be determined using the predictors that have been used for
conventional filled elastomers, or does the presence of ferromagnetic particles and the interfacial
layers between these particles and the rubber matrix require a new theory of failure to be
postulated?
Ciência sem Fronteiras / Science Without Borders Priority Area:
Nanotechnology and New Materials