Composite Hat geometry/ply definition

[Analyst]

Hi,
I’m analyzing a hat composite section.  In the analysis with HyperSizer the section has no radius.  The bottom cap width is measured from corner to corner (intersection of web and bottom cap) with the assumption that the reinforcing 0 cap plies are running along the width of the bottom cap.

In reality the section will have a radius and the 0 plies of the bottom cap will drop before the radius.  Therefore, the bottom cap stiffness is reduced based on how large the bottom cap to the web radius is.

Is HyperSizer taking any of the above mentioned into account during the analysis?  Do I need to reduce the width of the bottom cap (artificially) to match the actual section’s EA & EI?

Thank you,

[Phil]

You are correct that HyperSizer is not taking that bottom corner radius into account.  The length of the hat crown is taken to be from the mid-plane of the connection between the bottom crown and the webs.  Slightly reducing the crown width would seem like a reasonable way to account for this.  Are you seeing a large difference between the crown width and the width of the reinforcing plies?

[Analyst]

It depends where we choose to drop the 0 reinforcing plies of the cap & the size of the radius.  If we start the drop at the radius tangent (no drop offs in the radius) & the radius is large it could reduce the stiffness of the cap by 15%.
It is good to know that the width is measured from the intersection of the mid thickness planes of the cap & web.

Thank you Phil,