A measuring apparatus was devised to determine the dynamic physical pr
operties of a powder bed from the transfer function of vibration accel
eration that results from the direct application of random vibration t
o the powder bed. By using this apparatus, the variation of the stiffn
ess constant of a powder bed with various vibration forces and compres
sion forces was measured. The stiffness constant gradually decreased w
hen the vibration force exceeded a certain value. With respect to the
change in stiffness constant with compression force, the following exp
erimental equation was derived: k=SW(n), where k is the stiffness cons
tant of a powder bed, W the compression force applied to the powder be
d, and S and n are empirical constants.