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Author Topic: correct ortho definitions for S0 and S90 vs. a and b x and y dimensions of panel  (Read 1375 times)


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I developed a non-fea project trying to optimize an orthogrid panel design for pressure loading only. I assumed from all the images I see in hypersizer that define free body and orthogrid varibles that the "a" dimension is width of panel, the x axis left to right that I match up to the S0 deg web spacing direction, while the "b" dimension of panel is height, the y axis top to bottom that I matched to S90 deg web spacing direction. I run my load case this way and get optimized orthogrid design, that looks OK in viewer. Everything is ok at this point. Then I create an equivalent ANSYS FEA model for verification and to proceed with detailed design, and it shows large negative margins in S90 web.  I  go back to hypersizser, flip my a and b dimensions only freeze all orthogrid dimensions to the optimized solution, and then rerun hypersizer, now I get negative margins in S90 web similar to ANSYS FEM.
So my question is, did I get my a and b panel dimensions mixed up with respect to S0 and S90 web dimensions? where did I go wrong?


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By HyperSizer convention, the x-axis runs in the "a" direction, and the y-axis runs in the "b" direction. The zero stiffeners therefore run in the "a" direction as well.

So an orthogrid pocket that has S0 = 10 inches and S90 = 2 inches is long in the y-axis (b) direction because the space between 0 stiffeners is larger than S90.

I've attached the HyperSizer image of an orthogrid panel, and I've added a quick note showing where "a" and "b" are defined. Hopefully this clears things up! I think what you described is indeed the reverse of this.