Nonlinear Analysis of a thin composite laminate under large deformation
Dear Support Community,
I am currently working on the analysis of a highly deformed composite laminate. A very thin composite laminate sheet (ca. 0,4 mm) is 'clamped' (all DOFs constrained) at one end bent around 180° to form a 'c-shape' at the other. I am using the non-linear quasi-static solution option in OptiStruct, the composite part is made up of HEX8-elements with PCOMPLS property. When running the analysis the results (e.g bending moment (SPCF)) are by far stiffer than the predicted results. That got me wondering: Does OptiStruct regard the nonlinear behaviour of composite materials at high levels of strain (and therefore large displacements). I mean, does it take into account, that the moduli of the material behave nonlinear for very thin composites and very high levels of strain? I had a look into the OptiStruct help. It says there that 'classical lamination theory is used to calculate effective stiffness and mass density of the composite shell'. This is some information, but doesn't really answer my questions.
As always I would be very grateful for any helpful advice given.
Kind regards,
cfuser
Answers
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Could you please share the .fem and .out files?
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Hi,
only linear elastic composite material models (MAT8, MAT9, MAT9OR) are available in Optistruct.
Altair Multiscale Designer does support nonlinear composite materials.
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Composite laminate definition with solid elements have two main categories although the definition is using solid elements for both the types:
1. Solid Layered Composites
2. Solid Shell Composites (Continuum shell composites)
The first type is using regular first order or second solid elements. While using first one, where bending is predominant, solid elements tend to be very stiff. Several layers of solid elements through the thickness are typically required to correctly simulate a structural member in bending.
To overcome the above limitation, assumed strain functions are added to the elements to make them behave more like shell elements when loaded in bending. This integration scheme is called Continuum shells. This is what we have the second type. As of now we support only this scheme (Continuum shells). The first type is not yet supported. PFA material for same.
Indeed, Multiscale designer has wide range of nonlinear composite materials .The user material MATUSR has been added in HyperMesh 2019.1.1 (full version).Multiscale designer will be a part of Student Edition in upcoming version.
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