Shear characterization in soft polyurethane foams: A critical comparison among experimental approaches

The study addresses the lack of standardization for the evaluation of the shear properties of hyperelastic soft foams. The results of three different standards used for sandwich structures or rigid materials (ASTM C 273, BS 4370, ASTM D 5379) are compared using specimens with different geometries and aspect ratios. Displacements are captured using Digital Image Correlation applying texture correlation and an incremental approach on three flame-retardant foams with densities around 85, 63, and 46 kg/m³. The study examines secondary effects like bending moments and normal stresses, finding the Iosipescu method effective for hyperelastic foams, ensuring minimal material wastage and test repeatability.