Shrinkage stresses produced during the curing of the matrix in a two-phase material were studied. Specimens representing a typical two-phase material made of unplasticized epoxy as inclusions and plasticized epoxy as the matrix were studied photoelastically. The magnitude of stresses at the interface of a single inclusion in an infinite matrix during the transient period of curing depended only on the constant elastic modulus of the inclusion and on the instantaneous value of the matrix elastic modulus and it was independent of the amount of shrinkage of the matrix. In the case of a square array of inclusions in close proximity, the stress-distribution depended on both elastic moduli and the amount of shrinkage. The influence of the ratio of the space between inclusions and their diameter on the magnitude of stresses was also studied, in the case of already set matrices. © 1969, Sage Publications. All rights reserved.
