Abstract
Research in this laboratory has been directed toward the production and effects of beneficial residual stresses in plastics. Such stresses have been shown to have a dramatic effect on the impact strength and fatigue life of polycarbonate samples. For example, thermal quenching, in water or liquid nitrogen, of samples heated above their glass-transition temperature, resulted in an increase in the mean fatigue life of the material by as much as 20 times over that of annealed material. This increase is attributed in large part to the introduction of compressive stresses on the surfaces of the samples. This paper concentrates on methods used to measure residual stresses in the surface of the material and on the variation of these stresses with time after treatment. Three measurement techniques are described: (1) material slicing, (2) photoelastic fringe displacement and (3) the ASTM hole-drilling method. The advantages, limitations and comparative results of these three methods are described and analyzed.
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Hornberger, L.E., DeVries, K.L. Measurement of favorable residual stresses in polycarbonate. Experimental Mechanics 27, 94–98 (1987). https://doi.org/10.1007/BF02318870
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DOI: https://doi.org/10.1007/BF02318870