Abstract
This study is concerned with the mechanical behavior of Japanese lacquer film coated on a steel ball in process of moisture absorption. Normal stress generated at the interface between film and steel ball was obtained as a function of time by simulation, when the film was exposed to atmosphere at given relative humidities. The normal stress at the interface increased with relative humidity, and steeply at humidity above 60 %RH. The stress at 100 %RH reached three times as much as that at 60 %RH. Furthermore, the stress increased with the film thickness and with the decrease of radius of steel ball.
