Tuesday, 12 October 2004 - 4:45 PM

This presentation is part of : Micromechanics and Physics of Materials

A Multi-scale Nonlinear Viscoelastic Framework for Layered Composite Materials and Structures

Anastasia Hanifah Muliana, Department of Mechanical Engineering, Texas A&M University, 3123 TAMU, College Station, TX 77843-3123 and Rami M. Haj-Ali, School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive, Atlanta, GA 30332-0355.

This study presents a 3D multi-scale framework for the nonlinear viscoelastic analysis of both thin and thick section layered composite structures. The proposed modeling approach involves micromechanical constitutive models that recognize the nonlinear viscoelastic response of the matrix constituent in a given layer. A viscoelstic sublaminate model is formulated to generate the 3D through-thickness effective response. The sublaminate model represents the equivalent continuum of a repeating stacking sequence. The sublaminate model is implemented to interface with a standard displacement based 3D nonlinear finite element (FE) code. Incremental formulations in both temporal and stress domains are introduced at all levels. The Schapery nonlinear viscoelastic model is used to model the isotropic matrix in the micromodel. This modeling approach is general and can easily include temperature, moisture, and physical aging effects by incorporating time scale parameters in the matrix viscoelastic model. Experimental creep data from literature for glass/epoxy and graphite/epoxy are used in order to calibrate the in-situ material properties and verify the predictions for a overall response. Numerical applications are also presented for creep buckling and collapse analyses of various thin and thick-section composite structures. The proposed nonlinear 3D approach is computationally efficient for multi-layered structures.

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