Apparent masses of 15 male and 15 female subjects have been measured during exposure to various directions of horizontal vibration. Twenty vibration conditions were used in the experiment. In each of five directions (0, 22.5, 45, 67.5 and 90 degrees to the mid-sagittal plane) subjects were exposed to random vibration in the frequency range of 1.5-20 Hz at 0.25, 0.5 and 1.0 m s(-2) r.m.s. The five remaining conditions were selected to give measurements whereby the magnitude of the x-component of the vibration was fixed and the gamma-component changed and vice-versa. Two peaks were observed in the apparent masses. The first peak occurred at about 3 Hz and reduced in frequency with increases in vibration magnitude. The frequency of the first peak also reduced as the direction of vibration changed from 0 to 90 degrees. The magnitude of the peak increased as the vibration magnitude and direction increased. The second peak occurred at about 5 Hz and decreased in both frequency and magnitude with increases in vibration magnitude. There was no change in the frequency of the second peak with vibration direction, although the magnitude of the peak decreased as the angle of vibration to the mid-sagittal plane increased. Increasing the magnitude of the x-component of vibration whilst using a fixed y-component changed the magnitude of the first peak but did not change the frequency of the first or any characteristics of the second peak. In contrast, increasing the y-component of vibration whilst using a fixed x-component changed the frequencies and magnitudes of both peaks. Predictions of the response at 45 degrees by applying the principle of superposition to data measured at 0 and 90 degrees showed that the response of the body with direction was not linear. This implies that the apparent mass in non-orthogonal axes cannot be predicted from the apparent masses measured in orthogonal directions.
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机译：在暴露于各种水平振动方向的过程中，测量了15位男性和15位女性的表观质量。实验中使用了二十种振动条件。在五个方向中的每个方向（与矢状面中部分别为0、22.5、45、67.5和90度），受试者在0.25、0.5和1.0 m s（-2）r.m.s的1.5-20 Hz频率范围内遭受随机振动。选择其余五个条件进行测量，从而确定振动的x分量的大小，并更改gamma分量，反之亦然。在表观质量中观察到两个峰。第一个峰值出现在大约3 Hz处，并随着振动幅度的增加而降低频率。随着振动方向从0度变为90度，第一个峰值的频率也降低了。峰值的大小随振动大小和方向的增加而增加。第二个峰值出现在大约5 Hz，并且随着振动幅度的增加，频率和幅度均减小。第二个峰的频率没有随振动方向变化，尽管该峰的大小随与中矢状面的振动角的增加而减小。在使用固定y分量的同时增加振动的x分量的大小会更改第一个峰值的大小，但不会更改第一个峰值的频率或第二个峰值的任何特征。相反，在使用固定x分量的同时增加振动的y分量会更改两个峰值的频率和幅度。通过将叠加原理应用于在0度和90度下测得的数据来预测45度下的响应，结果表明人体的方向响应不是线性的。这意味着不能根据在正交方向上测量的表观质量来预测非正交轴上的表观质量。
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