Material characterization of ethylene vinyl acetate used in the construction of running shoes.

摘要

The following presents a testing protocol and experimental data of uniaxial extension, unconfined and confined compression of ACTEVA-52, a proprietary form of ethylene vinyl acetate (EVA) foam used in the construction of New Balance running shoes. Confined compression is proposed as a simple test method closely resembling hydrostatic loading. The experimental data generated are used to determine the bulk modulus of the material. Next, using uniaxial extension data, we determine the shear modulus of the material. The value of these parameters is used in a hyperelastic material model to numerically fit the experimental data. The Ogden model is shown to most closely match the stress-deformation response of the foam. The bulk modulus of the material is reported as 0.3 MPa, the shear modulus as 1.15 MPa. Experimental data show an increase in volume at low axial stretches in tension. For increasing stretch the change in volume becomes negative and the material contracts.