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You can use different hyperelastic materials models (such as
Neo-Hookean model, Ogden model, Mooney–Rivlin model, Arruda–Boyce
model etc.) to derive constitutive equations and discuss the test
results. The materials can be assumed to be incompressible
hyperelastic materials and you can use the stress-stretch
relationships to derive the constitutive equation. For an isotropic
and incompressible material, strain energy W can be expressed as a
function of the principal stretches. You may submit a report to
derive constitutive equations using principal stretches form. If it
is possible, you can further use test data to determine model
constants (Neo-Hookean model, Ogden model, Mooney–Rivlin model,
Arruda–Boyce model etc.).
Biaxial extension uniaxial tension Fig A3.1 Mechanical tests on uniaxial tension and biaxial extension for polymer materials 4.5 4.0 Uniaxial tension data 3.5 -Equbiaxial extension data 3.0 2.5 Nominal stress (MPa) 2.0 1.5 1.0 0.5 0.0 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 Stretch Fig A3.2 Example for uniaxial and equi-biaxial tension tests data Plot of nominal stress against stretch.