Thesis-1997-Hallett.pdf (7.21 MB)
Multiaxial strength and fatigue of rubber compounds
thesis
posted on 2010-10-20, 11:24 authored by Joseph F. HallettDespite real applications having complex triaxial loading, current physical test methods to predict component behaviour are mainly uniaxial. But previous work has indicated that there may be substantial differences between the rubber's uniaxial and biaxial behaviour and hence
through incompressibility, its triaxial properties. In order to quantify these differences equipment was developed to assess the biaxial performance of selected rubber compounds using inflated circular diaphragms. Although
allowing higher extensions than stretching a sheet in its own plane, such tests do not allow
stress and strain to be measured directly, requiring careful marking of the sample, or
calculation through simulation. On the grounds of perceived accuracy, the latter was chosen,
requiring accurate, general, elastic constants to high extensions. In this thesis the development
of this apparatus, along with the associated techniques is described, along with the
development of a new elastic theory. The tests on this new apparatus indicated significant differences between the uniaxial and biaxial strength and fatigue of rubber. In a unimdal test natural rubber (NR) is much stronger than styrene butadiene rubber (SBR) below 35pphr of carbon black. In a biaxial test though the converse is true, although there is some evidence of crystallinity in NR during the biaxial test.
Distinct differences were also found in fatigue between the two load cases. When plotted
against extension ratio the biaxial life of SBR was found to increase, while the converse is
true for NR. However if life is plotted against a function of strain energy, the biaxial life of
both polymers increases for a given energy.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Materials
Publisher
Loughborough UniversityRights holder
© Joseph HallettPublication date
1997Notes
Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.242878Language
- en
Supervisor(s)
P.S. OubridgeQualification name
- PhD
Qualification level
- Doctoral