Acoustic Reflection from a Plane Boundary having Variable Surface Parameters
Abstract
A possible technique for studying the acoustic reflection from continuous plane surfaces such as flat plates covered with thin anechoic coatings is discussed. It is particularly directed to complex coatings which include a regular array of non-homogeneous inclusions within their structures. The method involves the experimental determination of a position-dependent quantity which can be viewed as either a surface transfer admittance or a surface transfer mobility function. This function can then be used in a mathematical convolution procedure to determine the nature of the reflected wave from the surface when it is ensonified by an incident uniform plane wave arriving in a direction normal to the plate surface. The basic theory behind the proposed method is presented for a surface having a periodic, two-dimensional spatial variation. As a side issue, this approach raises a question as to the applicability of an 'average surface admittance' approach used previously to estimate reflection coefficients of Alberich coatings. The basic elements of an experimental system for measuring the surface admittance functions are discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1991
- Accession Number
- ADA236832
Entities
People
- C. I. Sach
Organizations
- Defence Science and Technology Group