J. D. Wenrick’s scientific contributions

This paper reports the study comparing tensile stress strain data taken on elastomeric materials using three different specimen geometries: a standard tensile bar or dumbbell, a ring, and an oval. It is shown that the tensile bar or dumbbell gives higher values for failure stress and strain than does either the ring or oval specimen. The ring, oval, and tensile bar show agreement for values of stress and strain above 100 per cent strain but below failure. For soft, low modulus stocks the ring and oval agree at low strains. For stock with tensile modulus values above 1000 psi, the beinding stress and strain, required to straighten the ring to its in-test configuration, significantly affect the data. Yielding, as defined in this paper, can be related to hysteresis effects and hence to the phenomenon known as cyclic softening. The stress as 300 per cent strain and the stress and strain at failure are not sufficient to characterize stress-strain behavior, particularly for thermoplastic elastomers.