MEASURING INSTRUMENT FOR ACOUSTIC VELOCITY OF TRANSVERSE WAVE AND YOUNG'S MODULUS AND/OR POISSON RATIO MEASURING INSTRUMENT USING THE DEVICE

摘要

PURPOSE: To calculate the Young's modulus and Poisson ratio of an object to be measured with high accuracy by calculating transversal acoustic velocity of transverse waves in a very small area after finding the acoustic velocities of longitudinal waves and leakage surface elastic waves with a solid- and liquid-state couplers acoustic lenses. ;CONSTITUTION: A solid-state coupler acoustic lens 1S is positioned against an object 20 to be measured with a surface polished to a mirror surface so that the planar end face of the lens 1S can be brought into contact with the object 20. A prescribed area of the object 20 is oscillated by converging longitudinal wave vibrations which are converted from electric signals by means of a piezoelectric element 18 through the lens 1S as indicated by the broken lines. When the area is oscillated reflected waves R_f and R_r are generated from the front and rear surfaces 20A and 20B of the object 20. The acoustic velocity of longitudinal waves is calculated from a prescribed expression by using the waves R_f and R_r and their interference waves. Then the acoustic velocity of leakage surface elastic waves is found from a prescribed expression by using a liquid-stage coupler acoustic lens 1L and interference waves of vertical reflected waves R_c and radiated waves R_e, etc. Thereafter, the acoustic velocity of the transverse waves of the object 20 is calculated from a prescribed expression by using the acoustic velocities of the longitudinal and leakage surface elastic waves. Moreover, the Young's modulus and Poisson ratio of the object 20 can be calculated by using the acoustic velocities.;COPYRIGHT: (C)1994,JPO&Japio