Vertical vibration model and seat comfort analysis for longitudinal axis roadheader

In order to understand the vertical vibration feature of the longitudinal axis roadheader and the comfort of the driver in cutting conditions, a damping vibration reduction model of the roadheader was established, and the international standard ISO 2631 was taken as the comfort evaluation index. Under two typical working conditions of the roadheader, i.e. sweeping and drilling, the stiffness-damping parameter characteristics of the seat system were analyzed to determine the optimal matching relationship. The vibration dissipation capabilities of various parameter configurations (I-original rigid seat parameter configuration, Ⅱ-“slightly discomfort” parameter configuration and Ⅲ-"comfort" parameter configuration) were compared and studied. The results show that the Root Mean Square (RMS) of the vertical weighted acceleration of the rigid seat I is greater than 0.8, and the driver’s subjective feeling is "uncomfortable", which is consistent with the experimental result; when the seat stiffness coefficient is greater than 700 000 N/m and the damping coefficient is greater than 34 000 N·s/m, the RMS of the vertical weighted acceleration of the seat under the two working conditions is less than 0.315 and the driver’s subjective feeling is "comfort". Compared with the rigid seat I, the RMS of vertical acceleration of damping seats ⅡI and Ⅲ decreased by 35.7%, 50.9% (sweeping condition) and 38.7%, 54.9% (drilling condition) respectively, and the peak frequency response decreased by 73.8%, 92.4% (sweeping condition) and 74.9%, 92.8% (drilling condition) respectively, indicating that the comfort of the driver of damping seats Ⅱ and Ⅲ has been greatly improved and the vibration dissipation capability is close to each other, which is consistent with the parameter matching results. By analyzing the frequency characteristics of cutting force and seat response, it is found that the first-order frequency of the cutting force is 1.66 Hz, which is close to the peak frequency of seat response of 1.65 Hz, implying that the cutting effect is the main component affecting the driver’s comfort. This study could provide reference for dynamic design and optimization of high performance damping seat of roadheader.