Contactless measurement of the elastic Young's modulus of paper by an ultrasonic technique

The use of a non-contact ultrasonic technique for the characterization of the in-plane elastic Young's moduli of paper is considered. The determination of these moduli from A, (fundamental antisymmetric plate wave mode) measurements, using the empirical technique introduced by Luukkala et al. (1971), is discussed: it is shown that the common low frequency approximation is not valid for paper, owing to its orthotropic structure. Numerical simulations are used to evaluate the validity domain of Luukkala's method. A new device was developed, and Young's moduli of various paper sheets were determined from A, measurements. These moduli values were found to be in good agreement with those measured using a common laboratory contact ultrasonic technique. (C) 1999 Elsevier Science B.V. All rights reserved.