Characteristics of Tangible Threshold Vibration

Abstract

Characteristics of threshold vibration tangible to the tips of fingers have been observed over a range from 5 cps to 1000 cps with a vertical vibration generator. It is found that the thershold amplitude of vibration φ is proportional to d²φ/dt² in the range of 5_??_150 cps, to φ in the range of 200_??_400 cps and to ∫∫φ(dt)² in the range of 500_??_1000 cps where φ is the displacement and is represented approximately by
_??_
where
φ: the threshold vibration amplitude in μ,
K: the minimum value of φ in μ,
ƒ: the frequency per sec,
h: a damping constant,
n₁ : the first order natural frequency of the vibration,
n₂: the second order natural frequency of the vibration.
Actually the values of the constants n₁, n₂ and K were
n₁=160 cps, n₂=500 cps and K=0.2μ.
It is concluded that the human body can be represented by a fine vibrograph, its magnification coefficient being equal to the product of that of displacement vibrograph and that of accelerometer.