Determination of paper stiffness and anisotropy from recorded bending waves in paper subjected to tensile forces

Experiments and theory for bending wave propagation of paper sheets in tension are presented. An all-electronic pulsed TV holography technique is used to record the bending wave field initiated by a laser pulse. A theory for bending wave propagation in tensile-loaded paper is developed. The bending waves are influenced by mechanical properties such as density, thickness, bending stiffness, anisotropy and also by tensile forces in the paper. The paper stiffnesses are determined by matching the measured deformation field with the calculated theoretical field. The results show that the bending wave pattern is strongly influenced by the tensile force. For a non-destructive on-line measurement of, e.g. stiffnesses and anisotropy in the paper machine the tensile force must be considered.

[1]  T. Chow,et al.  On the Propagation of Flexural Waves in an Orthotropic Laminated Plate and Its Response to an Impulsive Load , 1971 .

[2]  Karl-Evert Fällström,et al.  Transient Bending Wave Propagation in Anisotropic Plates , 1998 .

[3]  Staffan Schedin,et al.  MECHANICAL AND THERMAL EFFECTS IN A STEEL PLATE IMPACTED BY A FOCUSED LASER PULSE , 1997 .

[4]  Nils-Erik Molin,et al.  Mechanical properties of corrugated board as studied by holographic interferometry , 1992 .

[5]  S. Tsai,et al.  Introduction to composite materials , 1980 .

[6]  R Cusack,et al.  Improved noise-immune phase-unwrapping algorithm. , 1995, Applied optics.

[7]  R. E. Russo,et al.  Laser Ultrasonics on Moving Paper , 1999 .

[8]  Nils-Erik Molin,et al.  Transient bending waves in plates studied by hologram interferometry , 1989 .

[9]  K. Olofsson,et al.  Generating and recording transient bending waves in plates by pulsed lasers , 1996 .

[10]  L. Drain,et al.  Laser Ultrasonics Techniques and Applications , 1990 .

[11]  C. Vest.  Holographic Interferometry , 1979 .

[12]  S Schedin,et al.  Phase evaluation and speckle averaging in pulsed television holography. , 1997, Applied optics.

[13]  K. Olofsson,et al.  Stiffness and stiffness variation in paper measured by laser-generated and laser-recorded bending waves , 1994 .

[14]  Gary A. Baum,et al.  Determination of all nine orthotropic elastic constants for machine-made paper , 1979 .

[15]  L. Persson,et al.  A study of bending waves in infinite and anisotropic plates , 1997 .

[16]  Gary A. Baum,et al.  On-line measurement of paper mechanical properties , 1980 .

[17]  T. Kreis.  Holographic Interferometry: Principles and Methods , 1996 .

[18]  P Gren.  Pulsed TV Holography Combined with Digital Speckle Photography Restores Lost Interference Phase. , 2001, Applied optics.

[19]  S Schedin,et al.  Tomographic reconstruction of transient acoustic fields recorded by pulsed TV holography. , 1998, Applied optics.