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CSME 2020/08
Volume 41 No.4
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493-501
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Quasi-Apparent Mass of Vertical Whole-Body Shock-Type Vibrations
Jun-Woo Lee a, Dong-Jun Park a, Weui-Bong Jeong a and Se-Jin Ahn b
aDepartment of Mechanical Engineering, Pusan National University, Busan 46241, Republic of Korea.
bDivision of Energy & Electric Engineering, Uiduk University, Gyeongju 38004, Republic of Korea.
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Abstract:
The apparent mass of a seated body exposed to vertical whole-body vibrations can be used to develop equivalent mathematical models and anthropodynamic dummies to predict and measure seat transmissibility. This experimental study investigated the biodynamic responses of 15 subjects exposed to a shock-type vibration of varying conditions. The shock-type waveforms were produced by using the response of a one-degree-of-freedom model to a half-sine force input. Shock-types according to the vibration magnitudes and decay rates were presented for each input-force frequency. “Quasi-apparent mass” defined as a biodynamic response to shock-type vibration in this study was calculated from the acceleration and force measured at the rigid seat. The results revealed significant effects of magnitude and decay rate as well as frequency of the shock-type vibration on the quasi-apparent mass, which was nonlinear as shown at the previous studies with steady state vibration input. It was found that the peak frequency of the quasi-apparent masses was between 4 and 6 Hz, and their magnitude at the peak frequency decreased with increasing decay rate.
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Keywords: shock-type vibration, whole-body vibration, biodynamic response, Quasi-apparent mass; discomfort
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©
2020
CSME , ISSN 0257-9731
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