Some Current Research Interests
EQUI-BIAXIAL DYNAMIC CHARACTERISATIONS OF MAGNETORHEOLOGICAL ELASTOMERS
Principal Investigator: Professor Steve Jerrams
Magnetorheological Elastomers (MREs) are elastomers that contain ferromagnetic particles that can be aligned with an applied magnetic field resulting in an instantaneous and reversible change in the physical properties of the material. Research is underway to determine changes in high strain,dynamic, equi-biaxial behaviour of MREs using CER's DYNAMET and CAPRICE systems
MULTI-AXIAL ELASTOMER FATIGUE
Project Researcher: Dr Niall Murphy
Latest experimental results and analysis are concerned with the fatigue behaviour of non-strain crystallising rubber fatigued with a zero minimum load, with further testing planned to investigate if preloading elastomers will result in increases in fatigue life for the same mean stress.
SWELLING PHENOMENON AND ELASTOMER FATIGUE
Project Researcher: Dr John Hanley
The investigation involved determining the service life of elastomeric compounds (EPDM) which were subjected to varying degrees of oil swelling and cycled to failure in multi-axial fatigue. Analysis of fracture surfaces of the specimens and the experimental stress-strain data determined the mechanism of failure and confirmed that the fatigue life predictors of dynamic stored energy and a limiting value of residual elastic modulus are applicable.
LOCALISED STRESS SOFTENING, STRESS CONCENTRATION & FLAW SIZE
(IN PARTNERSHIP WITH THE DEUTSCHES INSTITUT für KAUTSCHUKTECHNOLOGIE DIK)
Project Researcher: Dr John McNamara
3D image correlation photogrammetry is a powerful tool in elastomer research, providing full-field deformation and strain results from applied loads. Complexities of elastomer samples can be so pronounced that theoretical and mathematical models have difficulty describing and simulating the behaviour of them, especially when including the effects of stress softening. With proper experimental results such as those obtained using this system, local effects can be analysed and resulting finite element models verified. Tomography was used in this project to detect internal flaws of up to 500 mm across; far bigger than previously considered present.
LONG-TERM STRESS RELAXATION OF ELASTOMERS
(IN PARTNERSHIP WITH THE DEUTSCHES INSTITUT für KAUTSCHUKTECHNOLOGIEN DIK)
Project Researcher: Dr Stephen Ronan
This research uses the super-position principle and dynamic mechanic analyses to allow the determination of long term stress relaxation and component life. This research has important benefits in sealing applications, where by measuring stress relaxation curves at different temperatures allows the long term stress relaxation behaviour of the sample at normal temperature to be predicted. Dynamic mechanical analysis of test-pieces can also be combined with the relaxation data to allow the physical relaxation processes to be separated from the chemical relaxation processes.
FATIGUE FAILURES OF EXTERNAL FEEDING TUBES, MATERIAL SELECTION & DESIGN (IN PARTNERSHIP WITH BEAUMONT HOSPITAL & THE UNIVERSITY OF DUNDEE)
Principal Investigators: Professor Steve Jerrams & Dr Tony Betts
Feeding tubes are generally made from polyurethane or silicon rubber and often fail due to their poor resistance to stomach acid. A research programme is underway to determine if alternative materials and design can alleviate this problem.