M. Rachik et al., Elastomer biaxial characterization using bubble inflation technique. II: Numerical investigation of some constitutive models, POLYM ENG S, 41(3), 2001, pp. 532-541
An elastomeric material was investigated with a bubble inflation rheometer,
and its mechanical behavior was modeled as a rubber-like solid. Classical
strain energy functions were considered and the hyper-elastic constants wer
e calculated by a direct identification procedure from simple uniaxial and
equibiaxial extension test data, and the results are compared against those
obtained by an inverse method from bubble inflation test data. The latter
amounted to minimizing a cost function and matching the measured response t
o a finite element analysis solution, which depended on the unknown materia
l parameters. The optimization employed the Levenberg-Marquardt algorithm a
nd Abaqus software to compute the cost function and its gradients. The cons
tants so obtained were further used in finite dement analysis, and the nume
rical results were compared with experiments. This study showed that the in
verse method, used to estimate the material parameters, is a good alternati
ve to the direct identification, especially since the latter often requires
homogeneous strain state, which is very difficult to obtain.