Tearing of rubber
Abstract
There have been several studies on the tearing of rubber materials since the
seminal paper on rupture of rubber was published by Rivlin and Thomas (1953).The
behaviour is typically characterised using a fracture mechanics approach whereby
the rubber has a geometrically independent relationship between crack growth rate
during tearing versus strain energy release rate. This approach works well under
conditions of steady tearing as the crack growth rate is easy to measure. However,
this approach is much harder to interpret under the condition where the rubber
exhibits discontinuous crack growth behaviour such as knotty tearing or stick slip
tearing.
Unfortunately, these are common tearing conditions observed in practice for filled
rubbers as well as for some unfilled rubbers, especially those such as natural rubber
that are capable of strain-induced crystallisation. Under these conditions it is not
clear what the actual crack growth rate is as the value typically given results from
the average of a very rapid tearing rate and a zero velocity tearing rate.
The aim of this work is to develop a new approach to characterise the unsteady
tearing behaviour of rubber in terms of the relationship between the rate of increase
in the strain energy at the crack tip just immediately prior to the onset of the tearing
which is quantified directly as the time derivative of the strain energy release rate ·
T ,
and the critical strain energy release rate T* required to propagate the crack. The
approach adopted in this study is then evaluated using a range of different
crystallising and non-crystallising rubbers as well as crystallising rubbers that have
been modified to alter their crystallisation over a range of different test temperatures.
Additionally, a new elastic-viscous transition diagram in association with the rate of
change in the strain energy release rate at the tip of the crack is presented.
Authors
Sakulkaew, KartpanCollections
- Theses [4116]