1-D beam/rod element with composite material

[ksi8518]

I'm trying to design spar-cap out of composite material.  It is easy to see how laminate stacking sequence in Hypersizer, however when Hypersizer sends to FE solver, in my case Nastran, it send material property as MAT1, which is isotropic.  How does this work for composite material?  Is it using smashed young's modulus? If so, what would be purpose of even creating stacking sequence and analysis?  What would be most accurate way to create 1-D element to use in Hypersizer? I'd like to optimize stacking sequence and flange width with Hypersizer.  Thank you.

[James]

HyperSizer will update the FEM properties based on the optimum beam and laminate configuration. Using the Nastran PBAR property and MAT1 cards, HyperSizer is sending the EA, EI1, EI2 and GJ stiffness terms to the FEM. This is all the stiffness properties FEA needs to know to classify the beam and return the axial load (P), bending moments (M1, M2) and torque (T) element loads.

HyperSizer will retrieve these loads and resolve the FEA element loads into object-based loads and then further into ply stresses and strains. The purpose of the HyperSizer analysis is to generate the margins of safety for the detailed beam configuration which is stored in HyperSizer, not the FEA model. The general stiffness properties also make it possible for HyperSizer to size the beam configuration and update the FEM without having to update the FE mesh.

For more information, see:
http://hypersizer.com/help/index.php#FE-Update/update-beam_export.php

-James

[ksi8518]

In that case, If we design spar-cab with Beam element, CBAR, then we would obtain orientation info. from FEA model.  So calculating buckling would be easy to see.  However, If we design spar-cab with Rod-element, CROD, then I'm not so sure how doe Hypersizer calculated MS. Is there any big difference? Thanks.

[James]

Once HyperSizer imports the loads from the FEM, all the analysis methods are done independent of the FEA. The element type will only affect the loads that are used in the HyperSizer analysis methods.

When CROD elements are used the FEA will only return Axial Load (P) for the beam. There will not be moments (M1, M2), shear (V1, V2) or Torque loads. So, the Axial load is the only load considered in the HyperSizer analysis methods.