Creep of Sandwich Beams with Polymer Foam Cores

Abstract

Polymer foam‐core sandwich panels are increasingly being considered for load‐bearing components in buildings. In addition to offering a high stiffness per unit weight, such panels give excellent thermal insulation and may be easily mass‐produced. But polymers creep at room temperature, limiting their use in structural applications. In this paper we model the creep of sandwich beams with linear viscoelastic polymer foam cores. A previous study indicated that the creep of a polymer foam can be described knowing the creep response of the solid from which it is made and the relative density of the foam. In this study, we combine the model for foam creep with the standard analysis of deflection of a sandwich beam to develop an expression for the creep of a sandwich beam with a polymer foam core. The results are compared with data from a series of tests on sandwich beams with aluminum faces and rigid polyurethane foam cores. The model gives a good description of their behavior at loading times up to 1,200 hours and unloading times of an additional 450 hours.