Calculation of the hull panel from Larsson

I've got a doubt from the scantling calculations at Larsson (page 294 from the second edition).

That's the Fig 14.20, titled Calculation of the hull panel for YD-40 . At the top, it gives the values for ultimate tensile strength, modulus, etc... But I cannot figure out how it's done.

I assumed that, going to the materials properties graph, with a Wf = 39%, I could get the same values. But they're completelly different. I tried taking half of the sum of upper and lower values, and all sort of combinations, but didn't come with the same results.

Anyone could help me out with this, please?

 

I have the first edition of the book, so my tables are a little different. I assume that this is a uni project? If it were for an actual project you would need much more specific info.

The fig I have for a basic laminate Fig 12.3 appears from my experience to be in line with a laminate of mostly CSM (Chopped strand mat) with one or two plies of WR (woven rovings) in it. Hence the 35% WF. (33% is equal to 2-1 resin ratio wchich is about normal for CSM).

I also note that the values are for "Minimum" properties which should be used for design.

Checking the graphs for a CSM-polyester laminate it appears to line up (roughly). Flexural values anyway.

What kind of laminate do you have in mind? Laminates need to be designed to each application. It is not as easy as steel or alluminium. Properties are far more variable but can be predictable. This is where you can start.

Brett