Volume 3, Issue 5 (September 1975)
New Model Material for Three-Dimensional Stress Analysis
This paper describes the manufacturing of a family of epoxies, the Poisson's ratio of which at the critical temperature is on the order of 0.4. The variation of Young's modulus, Poisson's ratio, shear fringe value, and critical temperature as a function of the amount of hardener, the curing temperature, and the curing time for a large range of these variables are presented as parametric curves.
Previously, epoxies used in three-dimensional analysis have all shown a Poisson's ratio of about 0.5, indicating incompressibility. The new compressible material has two advantages: (1) it is closer to the common engineering materials and (2) strains can be measured at interior points to supplement photoelastic analysis, or strain measurements can be used exclusively to obtain stresses throughout the body.