## 3 Results and Discussion
### The Subject Variability  
Figure 15 shows the total vibration transmissibility of the six subjects and their mean values, and Figure 16 shows the mean and standard deviation of the total vibration transmissibility of the six subjects. These results were obtained under grip force 30 N and thrust force 50 N with the W1 and SP1 posture. From Figures 15 and 16, it can be seen that the trends of the total vibration transmissibility of the six subjects were similar, but there were significant differences between these individuals around the peak transmissibility. The largest deviation of the transmissibility is 0.316, which occurred at the frequency of 47 Hz, and the mean value of the vibration transmissibility at this frequency is 1.23. This deviation and the mean value of the transmissibility are very comparable to the literature [16], but there is a difference of 14.2 Hz in the corresponding frequency. In addition, it can be seen from Figure 15 that each transmissibility curve has a distinct peak, with resonance frequencies between 25 and 37 Hz for the six subjects and a mean frequency of 27 Hz, all of these frequencies being within 16-50 Hz [13]. The large differences in individual vibration transmissibility may be related to their kinetic properties and anthropometric data, as well as changes in grip force, thrust force, and arm posture during the experiment [16]. Therefore, the experiment conditions should be strictly controlled and the influence on the test data should be reduced during the experiment. was less than or close to that of SP2 posture; the vibration transmissibility of SP1 posture is greater than that of SP2 after the intersection. The total vibration transmissibility of the wrist part increases with the increase of thrust force, the resonance frequency, and the resonance peak amplitude increase. Before the intersection point, the vibration transmissibility of SP1 posture decreases with the increase of thrust force, while the vibration transmissibility of SP2 posture is almost constant with the increase of thrust. The effect of grip force on the vibration transmissibility is mainly located near the resonance peak, and in the low frequency band, the change of grip force has almost no effect on the vibration transmissibility of the wrist part. The double peaks of the transmissibility curves may not be obvious or disappear due to individual data averaging. A common characteristic of the vibration transmissibility of the wrist area is that the vibration transmission characteristics of the wrist area are almost constant, while the grip and thrust force reach a certain value. The total vibration transmissibility is used to analyze the vibration transmission characteristics of the wrist area in this paper, which not only avoids large test errors due to the deviation of the sensor measurement direction but also is consistent with the requirements of ISO 5349 for assessing hand-transmitted vibration hazards based on the total vibration value. Therefore, the data from this study can be further used for hazard assessment of hand-transmitted vibration. The wrist site transmissibility on W2, W3, W4, and W5 postures differ significantly from those on W1 near the resonance peak, and the assessment of wrist site injuries by the model built on the response characteristics of the wrist site measured on W1 posture will result in overestimation or underestimation. Therefore, the effect of wrist posture should also be considered in the assessment of hand-transmitted vibration injuries in the workplace. Although there are many studies on the effects of arm posture, grip force, and thrust force on the vibration transmission characteristics of the hand-arm system, there are certain differences in the results of these studies, and the factors influencing the vibration transmission characteristics of the hand-arm system are not yet completely clear. The research in this paper further refines the vibration transmission characteristics of the wrist area.