15.3. Material Properties

15.3.1. Calibration Experiments

Experimental data was obtained via a simulation of a hyperelastic test suite with an Ogden hyperelastic material. The test suite specimens are shown here, with the dark areas indicating locations of the clamps:

Figure 15.1: Hyperelastic Test Suite: Test Specimens

Hyperelastic Test Suite: Test Specimens

The engineering-stress vs. engineering-strain results are as follows:

Figure 15.2: Hyperelastic Test Suite: Experimental Data

Hyperelastic Test Suite: Experimental Data

The uniaxial specimen is similar to ASTM D412-C (ASTM Standard D412, 2006).

The crosshead is displaced by 396 mm, giving a measured engineering strain in the gage section of 662 percent and a calculated engineering stress of 58.1 MPa.

The equibiaxial specimen is disc-shaped, with 16 equally spaced tabs about the circumference. The tabs are stretched 127.3 mm, resulting in a measured engineering strain in the gage section of 336 percent and a calculated engineering stress of 22.1 MPa.

For the planar specimen, the crosshead is displaced by 191.6 mm, giving a calculated engineering strain of 639 percent and a calculated engineering stress of 54.7 MPa.

15.3.2. Validation Experiment

A simulated tension-torsion experiment was performed on a thin strip. The specimen is similar to that specified in ASTM D1043 (ASTM Standard D1043, 2006) and is shown here:

Figure 15.3: Tension-Torsion Test Specimen

Tension-Torsion Test Specimen

The experiment consists of clamping each end of the specimen into the test apparatus, then stretching the specimen by 50 percent of its original gage length and twisting one end of the specimen for four complete revolutions. Following is the resulting moment-vs.-rotation data:

Figure 15.4: Tension-Torsion Experimental Data

Tension-Torsion Experimental Data

15.3.3. Material Properties

The Uniaxial, Biaxial, and Shear experimental test data given in the file is a set of engineering-strain vs. engineering-stress input. The five-parameter Mooney-Rivlin model model, fit to the experimental data up to 100 percent strain, is selected as an adequate representation of the material response.

Figure 15.5: Curve fitting using Mooney-Rivlin 5 parameter model

Curve fitting using Mooney-Rivlin 5 parameter model