An approach to characterize nonlinear viscoelastic material behavior using dynamic mechanical tests and analyses

Abstract

'T1 raditional methods to characterize materials that •*• exhibit nonlinear viscoelastic response, such as those materials used in the fabrication of high-altitude scientific balloons, require significant time for tests and analyses. Dynamic mechanical test and analysis techniques rapidly identify viscoelastic response, but these methods are appropriate for (and limited to) linear behavior. Herein, the authors present a model for nonlinear characterization based on Schapery's nonlinear viscoelastic theory extended to dynamic mechanical methodologies. Furthermore, the authors describe a test protocol for experiments to characterize the nonlinear viscoelastic response of materials using dynamic mechanical test and analysis methodologies. Several test cases are presented to validate the efforts, and these results show excellent agreement between predictions of nonlinear response and measurements from experiments.