METHOD FOR MEASURING SHEAR-WAVE RESONANCE FREQUENCY USING STRESS-WAVE RESONANCE METHOD BASED ON FLEXURAL-WAVE NODAL POINTS

摘要

A method for measuring a shear-wave resonance frequency in an elastic medium is provided to increase the reliability of a measured resonance frequency by measuring the resonance frequency for a shear-wave in a state of minimizing flexural-wave resonance. A method for measuring a shear-wave resonance frequency in an elastic medium includes the steps of: determining a distance d of a minimum resonance point of a flexural-wave from an end of a hollow body(1), which is composed of the elastic medium to be measured, by a formula 1 in case that the Poisson ratio of the hollow body(1) is 0.3333, by a formula 2 in case that the Poisson ratio of the hollow body(1) is 0.2, and by a formula 3 in case that the Poisson ratio of the hollow body(1) is a value except 0.2 or 0.3333; installing an accelerometer(3) which measures an acceleration signal at a minimum resonance point of one side, and generating a shear-wave to the hollow body(1) by having an impact on the minimum resonance point of the flexural-wave which exists on an opposite side to the accelerometer(3); converting the signal measured by the accelerometer(3) into a frequency domain by Fourier-transforming the measured signal, and calculating a displacement transfer function; and measuring a frequency having a maximum function value at the displacement transfer function and determining the measured frequency as the resonance frequency of the shear-wave. The formula 1 is d=0.2362xL-0.09xD, the formula 2 is d=0.2302xL-0.05xD, and the formula 3 is d=7.5(d0.333-d0.2L)(v-0.2)+d0.2.