METHOD AND INSTRUMENT FOR MEASURING LOSS COEFFICIENT, DYNAMIC MODULUS OF ELASTICITY, DYNAMIC MODULUS OF ELASTICITY IN SHEAR AND DYNAMIC POISSON'S RATIO OF BAR MATERIAL OF SHEET MATERIAL

摘要

PURPOSE:To determine the dynamic modulus of elasticity, dynamic modulus of elasticity in shear, and dynamic Poisson's ratio of a measuring material and to determine the loss coefft. thereof in accordance with the behavior of damping oscillation after stop of excitation by exactly supporting said material at the true nodal line in such a manner that the output of an oscillation sensor provided on the point supporting part thereof attains a noise level. CONSTITUTION:A bar material or the like is horizontally supported in the position predicted to correspond to the nodal line of the prescribed oscillation mode thereof and is carried by the oscillation sensor. The bar material or the like is then excited at the resonance frequency corresponding to the oscillation mode and is finely adjusted in such a manner that the sensor output attains a noise level to realize the point support at the true nodal line of the oscillation mode. The position of the loop of the oscillation mode in the proximate area of the resonance frequency is sinusoidally excited without contact. The oscillation displacement is measured by a contactless type displacement sensor in the position of the other loop. The true resonance frequencies are detected from the generation of the max. amplitude state and at least one of the dynamic modulus of elasticity, dynamic modulus of elasticity in shear and Poisson's ratio are determined from the detected frequencies. The excitation is stopped after the excitation in the max. amplitude state is maintained for the specified time and the loss coefft. is determined from the behavior of the damping oscillation.