## 4 Conclusions  
Within this research, a lifetime prediction method based on StressLife\({}_{\text{HCF}}\) was validated for the first time regarding the use of higher frequency fatigue testing. It can be stated that the temperature correction of the electrical resistance could be used to separate the influence of frequency-induced self-heating and, therefore, provide a reliable input variable for the StressLife\({}_{\text{HCF}}\) method. In summary, the following conclusions can be drawn:  
1. The StressLifeHCF method is also useful and reliable for test frequencies above 5 Hz. Therefore, an additional calculated value \(R_{corr}\) is suitable as a material response for the use of the method to compensate for the temperature influence occurring at high test frequencies. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \begin{tabular}{c} **Test Frequency** \\ **[Hz]** \\ \end{tabular} & \begin{tabular}{c} **Material** \\ **Response** \\ \end{tabular} & \begin{tabular}{c} **\(\mathbf{n^{\prime}_{total}}\)** \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{b}\) \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{c}\) \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{B}\) \\ **[K]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{C}\) \\ **[K]** \\ \end{tabular} & \
\begin{tabular}{c} \(\mathbf{K^{\prime}}\) \\ **[MPa\(\cdot\)****k\({}^{-1}\)]** \\ \end{tabular} &
\begin{tabular}{c} \(\mathbf{n^{\prime}}\) \\ **[-]** \\ \end{tabular} \\ \hline
80 & \(\Delta T\) & 0.039 & \(-\)0.032 & \(-\)0.839 & 42.73 & 3344421.32 & 184.18 & 0.065 \\ \hline
260 & \(\Delta T\) & 0.054 & \(-\)0.043 & \(-\)0.786 & 2.65 & 127611.30 & 226.25 & 0.096 \\ \hline \begin{tabular}{c} **Test Frequency** \\ **[Hz]** \\ \end{tabular} & \begin{tabular}{c} **Material** \\ **Response** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{n^{\prime}_{total}}\) \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{b}\) \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{c}\) \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{c}\) \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{B}\) \\ **[-]** \\ \end{tabular} & \begin{tabular}{c} \(\mathbf{C}\) \\ **[-]** \\ \end{tabular} & \
\begin{tabular}{c} \(\mathbf{K^{\prime}}\) \\ **[MPa\(\cdot\)****m\({}^{-1}\)]** \\ \end{tabular} &
\begin{tabular}{c} \(\mathbf{n^{\prime}}\) \\ **[-]** \\ \end{tabular} \\ \hline
80 & \(\Delta R_{corr}\) & 0.031 & \(-\)0.026 & \(-\)0.868 & 48.85 & 791644.00 & 113.01 & 0.205 \\ \hline
260 & \(\Delta R_{corr}\) & 0.045 & \(-\)0.037 & \(-\)0.817 & 4.60 & 27908.99 & 175.35 & 0.327 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Parameters from the StressLife\({}_{\text{HCF}}\) calculation for SAE 1045 +N steel for \(f=80\) Hz and \(f=260\) Hz. Figure 9: Comparison of the S-N curves according to StressLife\({}_{\text{HCF}}\) for SAE 1045 +N steel based on the change in temperature-corrected electrical resistance for 260 Hz (orange) and 80 Hz (blue), including constant amplitude test (CAT) data points for f = 80 Hz and f = 260 Hz for validation. 2. Frequency influences can be seen in cyclic deformation curves of load increase tests, where the first material response shifts to higher stress amplitudes for higher frequencies, resulting in a general extension of fatigue lifetime. For constant amplitude tests, a shift in the position of maximum cyclic softening to higher numbers of cycles at a higher frequency was also observed. 3. Competing processes must be taken into account during higher frequency fatigue. On the one hand, processes that reduce the fatigue lifetime due to heat build-up resulting in very high temperatures of the specimen have an effect by increasing the dislocation mobility. On the other hand, lifetime-extending processes have an effect, as the dislocation movement is slowed down due to the high test frequencies.