PreComp help

Hello all,

I am working on building the input files for a composite blade in PreComp. Specifically, I am working on the Internal Structure file.

The blade I am modeling has 8 laps and 8 nets and 0 webs. Each lap or net has 4 layers (3 of carbon fiber and 1 of fiberglass) with a given orientation. So as I understand it, in Precomp language I have 16 “sectors” (8 top and 8 bottom) and each sector has 4 “lamina” and each lamina has 1 “ply”. And in the webs section I would put a 0 and leave the rest blank.
Is this correct?

My final question is in regards to the xsec_node input. Even after reading the entire “User’s Guide to PreComp” I am still not really sure what this is.

Thank you for your help,
Harry Wornick
Harvey Mudd College & Los Alamos National Laboratory - Wind Turbine Clinic Team

Xsec_node is defined in the PREComp’s user guide Table:5, page num:11. I repeated the same info below for quick reference.

Real array input that identifies locations of sectors on the upper and lower surfaces. The array contains a sequence of values that specify x-coordinates of the sector boundaries. The x-coordinate is normalized with respect to the chord length and is referenced to the airfoil coordinate frame (Figure 7). In our sample file, we have three sectors on the upper surface, which imply four points that define sector boundaries. The x-coordinates of these four points are 0, 0.15, 0.50, and 1.0. Sector 1 is bounded by x-coordinates 0 and 0.15, sector 2 is bounded by x-coordinates 0.15 and 0.5, and sector 3 is bounded between x-coordinates 0.50 and 1.0. Note: The x-coordinates of sector boundaries must be positive and in ascending order. The first coordinate may be greater than 0 and the last less than 1. In this case, however, PreComp checks to determine whether there is a gap (no laminate) at the leading and trailing edges of the section and, if necessary, issues a warning to place webs at those locations.

Basically it defines how much of the portion each sector spans.

However, I could not get these values for the profiles defined in SANDIA report … 132569.pdf
I ended up measuring with the scale and considered the approximate values (assuming figures in the user manual are drawn upto scale). If anybody has this data (xsec_node) kindly post here. Thanks.