"Zero" and "non-zero" coupling and properties

[dean.rose]

I fully understand the coupling behavior exhibited by unsymmetric laminates, but when I toggle between "zero" and "non-zero" coupling, the laminate engineering property module computes identical properties. Is there a defect here?

[dean.rose · Accepted solution]

Simulation Composite Design’s laminate engineering property module determines a set of orthotropic material constants that yield equivalent behavior to an entire laminate.  However, a simple orthotropic material cannot exhibit all of the forms of coupling that an unsymmetric, unbalanced laminate can exhibit.  Consequently, if the laminate engineering property module is used on an unsymmetric and/or unbalanced laminate.

Design ignores all of the laminates coupling behavior that cannot be represented by an equivalent orthotropic material. Thus the computed orthotropic material constants are representative of an artificially symmetrized version of the actual unsymmetric laminate.

In Design, many types of analyses (e.g., First Ply Failure analysis) are affected by the zero vs. non-zero coupling setting.  When the user saves a newly defined laminate, the zero vs. non-zero coupling setting is also saved.  Any subsequent analyses that use the stored laminate will utilize the saved zero vs. non-zero coupling setting unless the user explicitly changes the setting prior to the analysis.