Effects of wet–dry cycling on the mechanical properties of Arundo donax L. used for the vibrating reed in woodwind instruments

摘要

The effects of wet–dry and moist–dry cycling on the mechanical properties of reed (Arundo donax L.) were investigated. Because water-soluble extractives were lost through wetting, the reed shrunk in its tangential direction, and its dynamic Young’s modulus and loss tangent decreased during wet–dry cycling. On the other hand, the reed swelled in its radial direction because of the recovery of cell collapse, which had been induced by drying from a green state. Consequently, the resonant frequency of the reed monotonically increased during wet–dry cycling, whereas no clear trend was seen in bending rigidity. During moist–dry cycling, the equilibrium moisture content of reed decreased slightly. Such a reduction in hygroscopicity was attributed to the aggregation of deliquescent extractives. The changes in the dimensions and vibrational properties of the reed specimens during moist–dry cycling were qualitatively similar to those during wet–dry cycling. These results suggest that the practical performance of woodwind reed changes irreversibly during continuous usage.