## 3 Results and Discussion
### Effect of Wrist Posture  
Each subplot in Figures 13 and 14 represents the vibration transmissibility of the wrist part under 5 different wrist postures, and the 9 subplots correspond to 9 different combined of grip forces and thrust forces; Figure 13 shows the SP1 arm posture and Figure 14 shows the SP2 arm posture. From the overall view of Figure 13, with the change of grip force and thrust force, there is no obvious regularity in the change of the relative magnitude of the vibration transmissibility of the five wrist postures under different grip force and thrust force, although the trend of the change of the vibration transmissibility under different wrist postures is similar. As seen in Figure 14, except for Figure 14d, the W5 resonance peaks are larger than those of the other four wrist postures. In order to more precisely analyze the differences in vibration transmissibility of the five wrist postures, the results of comparing the peak value of vibration transmissibility of the other four wrist postures with that of the W1 posture are summarized in Table 2.  
As seen in Table 2, the peak vibration transmissibility of W1 posture is larger than that of other postures when the grip force and thrust force are small, except for the grip force of 0 N and thrust force of 20 N; the upper right corner of Table 2 is \"+\", which indicates that the peak vibration transmissibility of W1 is smaller than that of other wrist postures when the grip force and thrust force are larger in SP1 posture. Most of the lower right corners of Table 2 are \"-\" and \"-\", indicating that in the SP2 posture, the peak vibration transmissibility of W1 is greater than or equal to that of the other wrist postures but less than that of the W4 posture. In conclusion, if the vibration damage of various wrist parts is evaluated in W1 posture, it may be overestimated or underestimated; therefore, the wrist posture should be considered when evaluating the vibration damage of wrist parts.  
Figure 14: The vibration transmissibility at the wrist part on different wrist posture (SP2). (**a**) g0 N, p20 N, (**b**) g0 N, p50 N, (**c**) g0 N, p80 N, (**d**) g30 N, p20 N, (**e**) g30 N, p50 N, (**f**) g30 N, p80 N, (**g**) g60 N, p20 N, (**h**) g60 N, p50 N, (**i**) g60 N, p80 N.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Arm**} & **Wrist** & \multicolumn{8}{c}{**Grip Force and Thrust Force**} \\ \cline{2-10}  & **Posture** & **g0 N** & **g0 N** & **g0 N** & **g30 N** & **g30 N** & **g30 N** & **g60 N** & **g60 N** & **g60 N** \\  & & **p20 N** & **p50 N** & **p80 N** & **p20 N** & **p50 N** & **p80 N** & **p20 N** & **p50 N** & **p80 N** \\ \hline \multirow{4}{*}{SP1} & W2 & + & - & - & - & + & + & + & + & + \\  & W3 & + & - & - & - & + & + & + & + & + \\  & W4 & + & - & - & - & + & + & + & + & + \\  & W5 & + & - & - & - & + & + & + & + & + \\ \hline \multirow{4}{*}{SP2} & W2 & - & - & - & - & - & - & - & - & - \\  & W3 & + & - & - & - & - & - & - & - & - \\ \cline{1-1}  & W4 & + & - & - & - & - & + & + & + & + \\ \cline{1-1}  & W5 & + & - & - & - & - & - & - & - & - \\ \hline \hline \end{tabular} Note:“+” means the transmissibility wave-peak of other wrist postures is higher than that of W1 posture, “-” means the transmissibility wave-peak of other wrist postures is lower than that of wrist1 posture, “-” means the transmissibility is approximately equal to that of wrist1 posture.  
\end{table}
Table 2: Comparison of the transmissibility of the wrist on the other four wrist postures to the wrist1 posture under different arm posture, grip force, and push force.  
Figure 13: The vibration transmissibility at the wrist part on different wrist posture (SP1). (**a**) g0 N, p20 N, (**b**) g0 N, p50 N, (**c**) g0 N, p80 N, (**d**) g30 N, p20 N, (**e**) g30 N, p50 N, (**f**) g30 N, p80 N, (**g**) g60 N, p20 N, (**h**) g60 N, p50 N, (**i**) g60 N, p80 N.