振動下における木材の静摩擦係数

抄録

In order to obtain some informations concerning the effect of vibration in vibratory cutting of wood, the coefficient of static friction under vibration was investigated. The experiments were carried out using a sample of wood block and as an antisample, a brass plate vibrating with low frequency 20-100Hz.
The coefficient of static friction under vibration could apparently be reduced. And the greater the acceleration of vibration, the more reduction of the apparent coefficient of static friction was obtained. Furthermore, the experimental results were in good agreement with the theoretical results.
Under a sinusoidal vibration with one degree of freedom, the apparent coefficients of static friction in the three directions, μ_x (parallel to the direction of vibration), μ_y (perpendicular to the direction of vibration), μ_π/4 (45°-direction to the direction of vibration), are given by the following formulas respectively,
μ_x=μ₀-λ, μ_y=√μ₀²-λ², μ_π/4=√μ₀²-λ²/2-λ/√2
where μ₀ is the true coefficient of static friction and λ=aω²/g (a=amplitude, ω=angular frequency, g=acceleration of gravity) is the ratio of accelerations.
Under three-dimensional vibration, furthermore, the apparent coefficient of static friction in the y-direction, μ_y, is given by the following formula,
μ_y=√μ₀²(g+z)²-x²-y/g
where x, y and z are the acceleration of vibration in the x-, y- and z-direction respectively.