複合正弦振動とランダム振動の評価法 : 振動の評価法2

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Compound sinusoidal vibrations with several frequency components and random vibrations of a continuons wide frequency band are often encountered in the environmental and industrial investigations. Although a few evaluation methods for these vibrations have been proposed, they are not available to all the cases, and the new method widely applicable has been required. A ratio scale called vibration greatness in the unit of VG was experimentally determined using the corrected ratio method proposed by W. R. Garner. This corresponds to loudness (sone) in psycho-acoustics. The object was to sum up the VG values of their frequency components. The relations between vibration greatness level (VGL) and vibration greatness (VG) on the whole body and on the hand, for the vertical and the horizontal vibrations, were obtained as in Fig. 2 and Table 1. For the evaluation of the compound sinusoidal vibrations, the vibration acceleration levels (VAL) of their frequency components were converted into VG values (VG_i) by Table 1 through their VGL values using Figs. 6 and 9 in Part 1. Next, these VG_i values were summed up in a similar method to one proposed by S. S. Stevens devised for assessment of noise. That is, VG_T=VG_M+0. 3((Σ__i VG_i)-VG_M where VG_M is the maximum value among VG_i values. These calculated values were compared with the observed ones which were sensationally obtained by the comparison of the compound sinusoidal vibration with the vibration of 20 Hz as the standard frequency. These two values are in good agreement with each other below the level of compound vibration of 55 VGL. For the assessent of random vibrations, threshold and equal sensation curves were determined for the random vibration with 1 and 1/3 octave-band. Their results on the whole body and the hand are shown in Fig. 6 and 7. VG values of the frequency components of the random vibrations of continuous wide frequency bands were obtained using these figures and Table 1, and were summed up with weighting factor 0. 3 for the data analyzed by the 1-octave band and 0. 13 for 1/3 octave band, in the same method as in compound sinusoidal vibrations. The calculated values were in good agreement with the observed values in which the random vibration was directly compared with the vibration of 20 Hz. The sensation difference between vertical and horizontal vibrations was observed for the 1-octave band ranbom vibration. Sensation of the vertical is severer by 10 dB than that of the horizontal vibration at the same vibration level above 16 Hz.
1971-01-10

複合正弦振動とランダム振動の評価法 : 振動の評価法2

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