A micro-to-meso sublaminate model for the viscoelastic analysis of thick-section multi-layered FRP composite structures |
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Authors: | Rami Haj-Ali Anastasia Muliana |
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Affiliation: | (1) School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0355, USA;(2) Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123, USA |
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Abstract: | Classical ply-by-ply analysis of multi-layered thick-section composite structures with tens of layers through the cross-section
is often impractical, especially when material nonlinearity and time-dependent effects are included. This study introduces
an integrated micromechanical-sublaminate modeling approach for the nonlinear viscoelastic analysis of thick-section and multi-layered
composite structures. The sublaminate model is used to generate three-dimensional (3D) effective nonlinear responses at through-thickness
material integration points with given spatial variations of strains determined from the trial strain increments of the standard
displacement-based finite-element (FE). The number of material integration points is determined by the resolution of the FE
discretization of the composite structure. The sublaminate model at a selected material point represents the effective nonlinear
continuum behavior in its neighborhood using the 3D lamination theory with uniform in-plane strain and out-of-plane stress
patterns through the representative layers. Therefore, the sublaminate has first-order stress and strain paths and cannot
recognize the local sequence of the layers. While this approach is very effective approximation especially in the case of
a very large number of repeating layers using relatively few elements (integration points) through the thickness, it cannot
be used to represent the interlaminar stresses or bending/extension/twisting coupling effects within a sublaminate. A previously
developed micromechanical model by the authors for a nonlinear viscoelastic unidirectional lamina is used for each layer in
the sublaminate. The proposed modeling approach is first calibrated and verified against creep tests on off-axis glass/epoxy
performed by Lou and Schapery (J. Compos. Mater. 5:208–271, 1971). Analyses for different thick-section laminated structures are presented using the integrated sublaminate with both shell
and 3D continuum elements. The proposed 3D nonlinear time-dependent sublaminate model is computationally efficient and robust
in analyzing multi-layered composite structures having large number of plies. |
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Keywords: | Viscoelastic Micromechanics Thick-section Multi-layered Sublaminate |
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