1. Technical Field of the Invention
Invention relates to the field of determination of properties of polymer materials.
2. Description of the Related Art
Prior attempts to identify combinations of specific polymers and polymer additives that would minimize residual stress have most often been done on a trial and error basis. Some attempts have been made in the literature to use ultrasonic techniques to measure residual stress in materials, but ultrasonic techniques are typically expensive, time consuming, and often not sufficiently sensitive to yield accurate measures. Ultrasonic residual stress measurement techniques have not in general evolved beyond academic studies.
From the foregoing it will be appreciated that improvements would be desirable in measurements of residual stresses and in determining the effect of various changes in the materials on these residual stresses.