EXPERIMENTAL STUDY OF STRESS WAVE INTERACTION IN PHOTOVISCOELASTIC PLATES.
Rept. for 1 Oct 63-5 Feb 65,
IIT RESEARCH INST CHICAGO ILL
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The objective of this investigation is to obtain experimental solutions to viscoelastic stress wave interaction problems pertinent to the design of protective structures. The methods of photoviscoelasticity and experimental viscoelasticity in general were employed. The model material used, plasticized polyvinyl chloride, was characterized mechanically and optically by creep tests at different temperatures using the temperature-time equivalence principal and by sinusoidal oscillation tests. Good agreement was obtained by the two methods of property determination. Photoviscoelastic plates were subjected to falling weight and air shock loadings. In the falling weight loading, stresses were determined on the boundary of a circular hole and at a similarly located point in the free field. It was found that the measured maximum compressive stress on the hole boundary is up to 17 percent higher than that obtained by using the free-field stresses and static stress concentration factors. In the air shock loading, stresses were determined at a free-field point and on the boundaries of circular hole and a rigid circular inclusion. The maximum compressive stress on the hole boundary is appreciably higher than the statically computed stress initially, but approaches it at later times. In the case of the rigid inclusion, differences of up to 25 percent between dynamic and static stresses were found. Author
- Structural Engineering and Building Technology