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Y. Morikawa
[SEN-I GAKKAISHI, Vol.51, No.7, pp.333-337, 1995]
A technique is proposed to estimate the local oscillation characteristics of a fabric strip that hangs down and freely swings with damping. An end of a cotton fabric strip was fixed to a holding rod rotatable around the axis, hung down, and oscillated in the air. The coordinates of a few marked points on the strip under free damped oscillation were simultaneously measured and recorded by a CCD camera system. The equation of motion of the strip was derived by extending that of a rigid body with considering the deformability of soft materials, based on which the damping coefficient and characteristic frequency at each measuring point were estimated from the damped oscillation curve. The characteristic frequency was uniform everywhere within experimental errors, while the damping coefficient differed depending on the measuring points. These characteristic values were also compared with those of the simple pendulum and physical one. This method was verified to be applicable to measuring and analyzing the local oscillation behavior of soft materials.