FROM MECHANICS TO ACOUSTICS: MODELLING POLYMER PROPERTIES

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Authors
  1. Taylor, E.L.
  2. Szabo, J.P.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
The relationships between experimental dynamic mechanical data and experimental acoustic data for polymeric materials were explored in this study. Two algorithms were written: a forward algorithm to convert dynamic mechanical data to acoustic data, and a reverse algorithm to extract acoustic material properties, such as sound speeds and attenuation coefficients, from experimental acoustic data. Testing of the forward algorithm was complicated by the lack of independent data on the polymers' complex Poisson's ratio, which is required as an input to the model. However, imputted literature values of the sound speed and attenuation coefficient for polyvinychloride resulted in good agreement between experimental and predicted insertion loss. The sound speeds and attenuation coefficients in the 10 - 100 kHz range were determined for two elastomeric materials. The extraction algorithm utilized an iterative approach to find the optimum fit between simulation and experiment, while constraining the polymer to a mechanical relaxation model. One advantage of such a constraint is that the derived acoustic properties are automaticlly consistent with the Kramers-Kronig relations.
Keywords
Poisson's ratio;Havriliak-Negami model;Sound attenuation
Report Number
DREA-TM-95-211 — Technical Memorandum
Date of publication
01 May 1995
Number of Pages
30
DSTKIM No
95-03098
CANDIS No
152231
Format(s):
Document Image stored on Optical Disk;Hardcopy

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