ABSTRACT
In the next step, the same samples are exposed to a simple preconditioning procedure. In this procedure a higher load is used for exactly ten cycles to elongate them. The small number of ten cycles was chosen to avoid any major fatigue damages. Additionally the preconditioning load amplitude with 185 N is quite small compared to the force that would have been reached at the ultimate elongation. After the preconditioning, the test samples are used like unconditioned ones and the uniaxial fatigue tests are executed. As before, identic force amplitudes with same repeat units were selected to determine the mean life-time of the preconditioned specimens. The results are summarized in Table 1. They show that the lifetime of preconditioned samples is markably shorter than of the virgin ones. The difference in lifetime is more significant for the lower amplitude of 90 N. For this amplitude, the impact of the preconditioning is higher due to the fact that the difference between the preconditioning amplitude and the fatigue test amplitude is larger.
