Ultrasonic waves propagation in absorbing thin plates application to paper characterization

Area of Science:

• Materials Science
• Acoustics
• Solid Mechanics

Background:

• Paper materials are complex cellulosic fibrous networks.
• Understanding ultrasonic wave propagation is key for non-destructive characterization.
• Existing research provides baseline phase velocity data for paper waves.

Purpose of the Study:

• To apply guided wave theory to thin, orthotropic, absorbing plates for ultrasonic wave propagation.
• To provide physical interpretations for the non-destructive characterization of paper materials.
• To numerically solve the reverse problem for material stiffnesses and damping factors.

Main Methods:

• Guided wave theory applied to thin orthotropic and absorbing plates.
• Reduction of propagation problem to two normal modes.
• Numerical solution of the reverse problem under small attenuation assumption.
• Experimental setup for measuring tracing paper damping factors.

Main Results:

• Propagation reduces to two normal modes, each dependent on four complex stiffnesses.
• First measurements of tracing paper damping factors obtained.
• Phase velocity measurements align with previous research.
• Shear wave velocities exhibit quasi-isotropic distribution in the paper sheet plane.
• Energy dissipation (absorption) occurs for each propagation mode.
• Attenuation values are generally small, with one notable coupling term.
• Anisotropy observed in the repartition of attenuation for quasi-longitudinal waves.

Conclusions:

• The study provides physical interpretations for non-destructive characterization of paper using ultrasonic waves.
• New experimental data on tracing paper damping factors and shear wave velocity distribution were obtained.
• The findings contribute to a deeper understanding of wave propagation and energy dissipation in cellulosic fibrous materials.