Precise and direct determination of the elastic constants of a cylinder with a length equal to its diameter

A cylinder made of a homogeneous isotropic material and with a length equal to its diameter is excited by axial percussion. Its axial displacement is detected by speckle interferometry. The two lowest frequencies, the first s ymmetric mode and first antisymmetric mode, are compared with the correspon ding nondimensional natural frequencies, calculated to six significant figu res using the Ritz method for 51 values of Poisson's ratio. The values of b oth dynamic elastic constants (shear modulus and Poisson's ratio) are found based on the quotient of the measured frequencies by using a table that is given. The method requires only one experiment and a simple calculator. Th e origin of the uncertainties is analyzed to improve the method's precision . The systematic uncertainty of the results shows relative values of 0.23% for shear modulus and 0.59% for Poisson's ratio. The values of the elastic constants calculated for a stainless steel test piece are compared with the values obtained by other methods. (C) 2000 American Institute of Physics. [S0034-6748(00)02706-4].