# Estimation of Impact Loads Transmitted to Vibro-Ripper Housing Using Transfer Path Analysis
## 3 Results and Discussion  
Vibration-based TPA was used to derive the loads in each direction and in link modules to quantify the impact load and its contributions to load transfer during vibro-ripper rock crushing.  
Variations in impact load generated in the housing through the link modules over a 0.6 s timespan are shown in Figure 10. Time-domain TPA showed the loads to be transmitted to the ripper housing, with quantitative values provided in Table 5. Directional contributions to the impact transmission were analyzed in estimating loads generated and transmitted in the X, Y, and Z directions, yielding values of 67.1, 59.1, and 67.5 kN, respectively.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Mode No.** & **Mode Shapes** & **Natural Frequency (Hz)** \\ \hline
1 & Bending and torsion & 75.5 \\
2 & Bending & 124.9 \\
3 & Bending & 134.1 \\
4 & Bending & 181.8 \\ High & Bending & 294.9 \\ High & Torsion & 459.6 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Results of the modal experiment.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Path No.** & **Axis** & \multicolumn{2}{c}{**Load (kN)**} & \multicolumn{2}{c}{**Maximum Load**} \\ \cline{3-5}  & & **+Dir.** & \(-\)**Dir** & **(kN)** \\ \hline \multirow{3}{*}{LH Path 1} & X & 7.6 & 7.8 & 7.8 \\  & Y & 7.4 & 7.0 & 7.4 \\  & Z & 1.5 & 1.3 & 1.5 \\ \hline \multirow{3}{*}{LH  
Analysis results are shown in Figure 11 for the frequency domain, representing the contribution of each major path to the final load transmitted to the housing during ripper operation. The results indicate that the main contributions were made in the X and Z directions with respect to load transmission, with a relatively small contribution in the  
Figure 10: Calculated impact load profile for each path of the vibro-ripper. (**a**) LH path; (**b**) RH path.  
Y direction owing to the motion of the shank assembly being mainly in these directions. Furthermore, the maximum load occurred in the frequency domain of -50 Hz, whereas the load transmitted to the housing was relatively insignificant at frequencies above 100 Hz.  
The TPA method yielded an impact load of 193.7 kN, compared with the striking force of 220 kN measured using the load cell (a difference of 12.3%). Thus, the reaction force produced during striking by the shank was damped mainly by the gearbox and isolation rubber and was ultimately transmitted via the link modules to the housing. The results confirm the applicability of the TPA method to a structure with impact loads and vibration. This method accounts for energy loss as a result of vibration, noise, hydraulic heat, and reaction force during shank striking work. An evaluation of the reliability of this method requires additional study using computational and numerical engineering approaches to assess load transfer through the link modules, as well as further tests of the material properties of the link modules.  
Additional analyses employing load estimation and evaluation techniques might lead to the development of a new method for evaluating the life-cycle durability of key parts of rock-crushing devices, with the operational state of various parts being closely related to the durability and performance of mechanical equipment. In addition, the impact loads of this study relevant to each component and direction can be used as input parameters for numerical analyses of vibro-rippers.  
This study did not consider the Load Transfer Characteristics of structure materials and the dynamic response of components during the working process of the vibro-ripper. Overcoming this limitation would require an assessment of the reliability of the load estimates through vibration-based TPA by introducing the computer aided engineering (CAE) method, which considers the physical properties and dynamic response of the ripper's components.