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Description:
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Fiber Metal Laminates (FML ) are hybrid composites with alternate layers of
orthotropic fiber reinforced polymers (FRP ) and isotropic metal alloys . FML can exhibit
a nonlinear thermo -viscoelastic behavior under the influence of external mechanical and
non -mechanical stimuli . Such a behavior can be due to the stress and temperature
dependent viscoelastic response in one or all of its constituents , namely , the fiber and
matrix (within the FRP layers ) or the metal layers . To predict the overall thermoviscoelastic
response of FML , it is necessary to incorporate different responses of the
individual constituents through a suitable multi -scale framework . A multi -scale
framework is developed to relate the constituent material responses to the structural
response of FML . The multi -scale framework consists of a micromechanical model of
unidirectional FRP for ply level homogenization . The upper (structural ) level uses a
layered composite finite element (FE ) with multiple integration points through the
thickness . The micromechanical model is implemented at these integration points .
Another approach (alternative to use of layered composite element ) uses a sublaminate model to homogenize responses of the FRP and metal layers and integrate it to
continuum 3D or shell elements within the FE code . Thermo -viscoelastic constitutive
models of homogenous orthotropic materials are used at the lowest constituent level , i .e . ,
fiber , matrix , and metal in the framework . The nonlinear and time dependent response of
the constituents requires the use of suitable correction algorithms (iterations ) at various
levels in the multi -scale framework . The multi -scale framework can be efficiently used
to analyze nonlinear thermo -viscoelastic responses of FML structural components . The
multi -scale framework is also beneficial for designing FML materials and structures
since different FML performances can be first simulated by varying constituent
properties and microstructural arrangements . |