## 4 Torsional Stiffness Analysis
significantly (the slope is \(3\times 10^{-2}\) s/mm), while the period has changed inconspicuously (the slope is 0 s/mm). The peak-to-peak torsional stiffness of the system under different \(E_{\text{rec}}\) is 0.57, 0.60, 0.64, 0.68, and 0.71 Nm/arcmin (the slope is 3500 N/arcmin), and the average values are 74.34, 74.35, 74.33, 74.34 and 74.33 Nm/arcmin (the slope is 0 N/arcmin), respectively. It can be seen from the figure that the peak-to-peak value of torsional stiffness increases with the increase of \(E_{\text{rec}}\), but its mean value does not change significantly. The Angle Error \(E_{\text{dec}}\) of the Crankshaft Bearing Hole on the No. 1 Carrier vs. the Torsional Stiffness  
Under similar conditions as described in Section 4.2, here we analyzed the change in the rotation angle error of the crankshaft bearing hole on the No. 1 carrier to \(E_{\text{dec}}=0\). 000\({}^{\circ}\), 0. 001\({}^{\circ}\), 0. 002\({}^{\circ}\), 0. 003\({}^{\circ}\) and 0. 004\({}^{\circ}\). Through simulation analysis, the corresponding influence curve of the system's torsional stiffness is obtained in Figure 5.  
It can be analyzed from Figure 5 that the curve of dynamic torsional stiffness with time presents an approximately smooth cosine curve. However, the phase difference of different curves does not evidently change (the slope is 6 \(\times\) 10\({}^{-2}\) s/\({}^{\circ}\)), and the period has not changed obviously (the slope is 0 s/\({}^{\circ}\)). The peak-to-peak torsional stiffness of the system under different \(E_{\text{dec}}\) are 0.46, 0.47, 0.45, 0.48, and 0.46 Nm/arcmin (the slope is 0 N/arcmin), and the average values are 74.30, 74.32, 74.31, 74.32, and 74.30 Nm/arcmin (the slope is 0 N/arcmin), respectively. It can be seen from the figure that the peak-to-peak value and average value of torsional stiffness have no obvious changes with the increase in \(E_{\text{dec}}\). The Angle Error \(E_{\text{dec}2}\) of the Crankshaft Bearing Hole on the No. 1 Beveloid Gear vs. Torsional Stiffness vs. Torsional Stiffness  
Under other unchanged conditions, we changed the angle error to \(E_{\text{dec}}=0.000^{\circ}\), 0.001\({}^{\circ}\), 0.002\({}^{\circ}\), 0.003\({}^{\circ}\), and 0.004\({}^{\circ}\). Through simulation analysis, the corresponding influence curve of the system's torsional stiffness is obtained in Figure 6.  
From Figure 6, it can be found that the dynamic torsional stiffness exhibits approximately sinusoidal fluctuations with time. The phase difference of the different curves increases relative to Figure 5 (the slope is 2.5 \(\times\) 10\({}^{-1}\) s/\({}^{\circ}\)); however, the period has not changed obviously (the slope is 0 s/\({}^{\circ}\)). The peak-to-peak torsional stiffness of the system  
Figure 5: Dynamic torsional stiffness under different \(E_{\text{dec}}\). under different \(E_{\rm{0 eg}}\) are 0.45, 0.46, 0.45, 0.44, 0.45 Nm / arcmin (the slope is 0 N/ arcmin), and the average values are 74.30, 74.32, 74.31, 74.32, 74.30 Nm/ arcmin (the slope is 0 N/ arcmin), respectively. It is obvious from the figure that the peak-to-peak value and average value of torsional stiffness have no obvious change with the increase of \(E_{\rm{0 eg}}\).