Test Method Development, Deformation and Failure Strength of Rigid PVC Structural Foams

Abstract

A study has been conducted to develop a proper test method to evaluate deformation behavior and failure strength of a rigid PVC structural foam material (Divinycell H80) with a nominal density of 80kg/m3. Examination of the foam microstructure revealed that the cell aspect ratio is near unity in the in-plane directions but greater than one in the out-of-plane (rise) direction. To investigate the effect of test specimen geometry on compression properties, foam specimens with both straight-sides and reduced-gage sections were designed, fabricated and tested. The effect of aspect ratio in the gage section of specimen on foam properties was examined. To determine foam tensile properties, specimens with different crosssectional dimensions in the gage section were used. Foam elastic properties, nonlinear constitutive relationships, strength and failure modes were all obtained in different loading conditions, in both in-plane and out-of-plane directions. Test results reveal transversely isotropic characteristics of the foam material. To evaluate foam shear properties a miniaturized shear test method, similar to the ASTM standard test, was developed. Shear loading and unloading experiments were carried out to identify the causes of large shear deformation observed in the tests. The damage and failure modes of the foam material under different loading modes were also examined, both macroscopically and microscopically.