Multiaxial-stress studies on rigid polyurethane foam

Abstract

Thin-walled tubes of rigid polyurethane foam, at 5 lb/cu ft and 4 lb/cu ft nominal density, were subjected to combined stresses. A universal-test machine applied the axial tensile or compressive stress; an independent pressurization system supplied the internal pressure to the specimen. Changes in diameter, length and wall thickness were measured at room temperature and at −50°F. Failure envelopes in 2-dimensional stress space were obtained for the two densities at room temperature and for the greater density at −50°F. For the wall-thickness range investigated (0.15≤t≤0.25 in.), no effect on the failure envelope was observed. Material constants were obtained in terms of orthotropic elastic theory (at 5 lb/cu ft and room temperature) to describe the material in terms of structure.