ABSTRACT
VII. Thick Plate Wave Measurement Techniques 298
VIII. Out-of-Plane Measurement Techniques 299 A. Introduction 299 B. Transduction 302 C. Instrumentation 305
IX. Miscellany 307
References 308
I. INTRODUCTION
I plan to examine ultrasound in paper within a limited scope. I will review in-plane and out-of-plane ultrasonic diagnostics of paper. I will outline the mechanics under lying these techniques. I will conjecture on physical meaning. I will address issues of experimental difficulty, and I will compare techniques. To my knowledge, there is no other unified exposition of these important topics as applied to paper. I believe this leaves me an opening for a contribution. On the other hand, I do not include onmachine measurements. I omit the influences of papermaking variables on ultrasonic velocity and the relationships between ultrasonic stiffnesses and other physical prop erties. I will not talk about ultrasonic processing in the pulp and paper industry. These subjects are adequately entertained elsewhere. I acknowledge that my nar rowed perspective excludes important works that would be referenced in a more even account of ultrasound in paper. I rationalize my convenient lapses by appeal to the charge of the book. The objective of these volumes is to critique experimental meth ods. The intent is not to emphasize papermaking or paper physics.