This work is focused on polymorphic uncertainties in the framework of constitutive
modeling for transversely isotropic materials. To this end, we propose a hybrid
fuzzy-stochastic model, where the stochastic part accounting for aleatory
uncertainties of material parameters is expanded with the multivariate polynomial
chaos expansion. In order to account for epistemic uncertainties, polynomial chaos
coefficients are treated as fuzzy variables. The underlying minimum and
maximum optimization problem for the fuzzy analysis is approximated by
-level
discretization, resulting in a separation of minimum and maximum problems. To
become more universal, so-called quantities of interest are employed, which allow a
general formulation for the target problem. Numerical examples with fuzzy,
fuzzy-stochastic, and hybrid fuzzy-stochastic input demonstrate the versatility of the
proposed formulation.