3aED1. On-line contactless measurement of the elastic modulus of a moving sheet by ultrasonic method.

Session: Wednesday Morning, June 18

Author: Mazen Khoury
Location: E.F.P.G, Lab. de Genie des Procedes Papetiers, UMR 5518 CNRS, Domaine Univ. 461, rue de la Papeterie, 38402 Saint Martin d'Heres, France
Author: Andre Schroder
Location: Elfatochem-service UMR, 92303 Levallois Perret, France
Author: Guy E. Tourtollet
Location: Domaine Univ., 38044 Grenoble, France


There is still a strong interest in the paper industry for a contactless method that would allow the measurement of the elastic modulus of paper and of the anisotropy of this modulus in the sheet plane. A contactless method is presented that enables the measurement of the transmission coefficient of sound through a paper sheet, in the frequency range 200-- 800 kHz, for incidence angles between -66 and +66. These measurements can be performed on a moving sheet at velocities in the same range as those observed on a paper machine. From the state equation of plate waves, the possibility to calculate the elastic modulus of paper was demonstrated by using only the equation of the first antisymmetric mode, without neglecting any term of it, contrary to what is commonly used in the literature. This model fits very well with measurements made and leads to consideration of the development of an on-line version for use on industrial paper machines.

ASA 133rd meeting - Penn State, June 1997