Compression testing of foamed plastics and rubbers for use as orthotic show insoles.

Thirty-one materials have been tested in compression in order to generate the stress (force per unit of cross-sectional area) versus strain (deformation) behaviour, for the purpose of assessing the suitability of various foamed plastics and rubbers as shoe insole materials. It was found that the materials could be classified into three distinct categories (very stiff, moderately deformable and very deformable) according to the shape of the characteristic stress versus strain curve. The moderately deformable group has been selected as the most promising for clinical application.