## 4 Influence of Notch Location on the Vibration Characteristics  
The natural frequency analysis results make it difficult to use experimental methods. The current research uses the generated FE model to predict natural frequency behavior in different modes. The direct method of testing the specimen is the only actual measurement method, and measuring the natural frequency in all ranges would be difficult. As shown in the reports of [PERSON]. [PERSON] et al. (2017) and [PERSON] (2018), it was shown that the FE model was used to analyze specimens when the results that could be contained in all seven modes were analyzed. The natural frequency effect from the experimentally measured natural FE model was compared with the calculated value from the finite element method model. The items in shape modes 1-7 are close to the experimentally measured values when observing the calculated results from the model. The values shift as the shape mode progresses from the seventh shape mode. The calculated values obtained from the finite element method model are higher than the experimentally obtained values. The Figure shows that the calculated values from the FE model and the experimental values tend in the same direction. In the section, take the V-shaped workpiece plate, and change the position of the notch. There are straight and oblique types, each divided into two notched plates. This is shown in Figure 15 for an oblique traverse in which the notch moves in the reverse direction and Figure 16 for a straight traverse in which the notch moves in the same direction. The shape modification will determine the proportion by taking the distance between the notch: L and from the notch to the workpiece edge: H by the dimensionless proportion, as shown in Table 9. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Mode** \\ **Shape** \\ \end{tabular} } & \multicolumn{4}{c}{**Natural Frequency (Hz)**} \\ \cline{2-7}  & \multicolumn{2}{c}{**Virgin**} & \multicolumn{2}{c}{**Hole**} & \multicolumn{2}{c}{**V-Notch**} \\ \cline{2-7}  & **Experiment** & **Simulation** & **Experiment** & **Simulation** & **Experiment** & **Simulation** \\ \hline
**1** & 10 & 11.290 & 11 & 10.791 & 11 & 11.103 \\
**2** & 39 & 30.998 & 33 & 29.893 & 49 & 31.598 \\
**3** & 65 & 69.777 & 66 & 66.958 & 59 & 66.780 \\
**4** & 98 & 109.030 & 95 & 105.290 & 107 & 135.950 \\
**5** & 121 & 113.250 & 109 & 105.290 & 137 & 137.140 \\
**6** & 189 & 196.580 & 195 & 187.710 & 202 & 179.880 \\
**7** & 225 & 207.780 & 213 & 197.530 & 278 & 237.470 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Natural frequencies of low carbon steel from experiment and simulation. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Direction** & **Specimen Label** & **L/H** \\ \hline \multirow{5}{*}{**Direct**} & V\_D\_1 & 0.22 \\  & V\_D\_2 & 0.45 \\  & V\_D\_3 & 0.67 \\  & V\_D\_4 & 0.90 \\  & V\_D\_5 & 1.12 \\ \hline \multirow{5}{*}{**Slide**} & V\_S\_1 & 0.20 \\  & V\_S\_2 & 0.43 \\ \cline{1-1}  & V\_S\_3 & 0.66 \\ \cline{1-1}  & V\_S\_4 & 0.86 \\ \cline{1-1}  & V\_S\_5 & 1.12 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Dimensionlessness of full V notch modified. The natural frequency is found in the mode range, the maximum value in straight-tuned workpieces in dimensionless proportions is 1.12, and the tendency of the natural frequency tends from small to large values, starting from 0.22, 0.45, 0.67, 0.90, and 1.12 accordingly. In addition, it was found that the smallest natural frequency values in modes 9-14 were at 0.67 and 0.45, respectively, and would return in the same order as in the first set at mode 15. The results are shown in Figure 17. When brought, test the workpiece by a method with a good test set calibrated. Taking the set of values from the natural frequency in mode 1 (Figure 18), the dimensionless proportions tested were 0.22, 0.67, and 1.12, respectively. The natural frequencies were 9, 9.26, and 11.00 Hz, respectively.