Elasto-Opt

Recording, simulation and evaluation of the thermomechanical damage mechanisms of elastomer components under dynamic mechanical stresses
FKM 2015
Issue number 324
Project no. 299
93 pages

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Abstract:
Investigations
were carried out on a natural rubber-based elastomer compound (60 Shore A) to characterize mechanical and thermal properties. Both
turned out to be significantly dependent on temperature. At the same time,
investigations with parallel measurement of the infrared spectrum of the sample surface showed that
the self-heating of the material under dynamic load is very pronounced,
so that the material properties can change significantly even without external temperature changes during
use. Investigations into the service life of the material were carried out
on hourglass samples and various component samples. Here, too,
showed a visible dependence of the service life on the temperature.
In order to make both the changes in properties and the reduced
service life with increasing temperature calculable, a thermoviscoelastic material model
was first developed, which, coupled bidirectionally, reproduces the mechanical and thermal material behavior
. With this model, the heating of the material due to mechanical
stresses can be calculated using finite element simulation (FE), whereby the
mechanical behavior can change depending on the prevailing temperature.
This material model was integrated into a new method that can estimate local temperatures on
the basis of a sequential load-time curve. Here, the self-heating obtained from the FE simulation is offset segment by segment
with the analytically calculated
temperature changes due to the exchange with the environment and a continuous
temperature profile is determined.
The overall objective was to develop a conceptual approach for temperature-dependent service life analysis.
This describes the procedure from experimental material characterization
and Wöhler line generation, through FE analysis and computational temperature estimation,
to temperature-dependent damage accumulation. Finally, the concept
was validated using the Hourglass sample and applied as an example for the service life analysis of an elastomer bearing
.
The objective of the research project was achieved.