Abstract
The mechanical and optical properties of a transparent epoxy are described, the response of which can be ‘locked-in’ at a critical temperature. The Poisson's ratio of this material is about 0.4, which is closer to the Poisson's ratio of common engineering materials than is that of the commonly used epoxies. Since the material is compressible, strain measurements on relaxed slices permit the complete determination of the stress field. Examples of applications to a solid and hollow sphere and to a tube, subjected to diametral compression, are given. The method permits the solution of three-dimensional problems by use of (1) photoelastic data only, (2) the moiré method only, or (3) mechanically obtained data only, or different combinations of them.