Abstract
LONG ago it was remarked by Brewster that a transparent elastic solid such as glass ceases to be optically isotropic when it is bent or otherwise strained by external forces. It then shows chromatic effects in the polariscope, which vanish if the state of strain be relieved. That was the beginning of photo-elasticity, a science which, many years later, has become developed into a powerful means of investigating complex conditions of stress for the information of the engineer. It can readily be applied in cases which are too complicated for mathematical analysis; and even in less complex conditions photo-elastic experiments are often highly useful, providing short-cuts to the required results, or confirming the analysis of the mathematician. Whether the distribution of stress is simple or otherwise, the photo-elastic method makes the mode of distribution strikingly apparent. The polariscope is an incomparable showman, as entertaining as it is instructive. It appeals alike to the mathematical and the non-mathematical mind. The distribution of stress exhibited by the transparent solid applies to an engineering material such as steel, provided the elastic limit is not passed.
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EWING, J. Photo-Elasticity. Nature 129, 264–266 (1932). https://doi.org/10.1038/129264a0
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DOI: https://doi.org/10.1038/129264a0