Stress-strain measurements alone provide insufficient information to a
ppropriately assess the fatigue behaviour of TPEs. However, such measu
rements do supply important preliminary information concerning structu
ral changes, and they help define stress values for further investigat
ions. In stress-controlled or strain-controlled dynamic tests based on
hysteresis measurements, changes of characteristic values, such as ex
pansion or impedance values, are used to define upper stress limits.