Section modulus

Hi,

Could some one tell how to calculate section modulus of T section:

is it correct?

SM= I/Y

AREA = stem area + flange area

Y: centrod location measured from stem or Y from flange


Y = centroid location = sum(area.lever) / AREA

I= [ sum(area.lever^2) +sum(bh^3/12) ] - AREA. Y^2

???

For T 65x50x7 mm it gives me SM=8.6 cm^3, while it is 7.1 cm^3
How it comes?

 

Follow this link and look at the spreadsheet on section modulus

http://www.boatdesign.net/forums/downloads.php?do=cat&id=1

Who told you it was not 8.68 cm3 ?
If a commercial section what you are taking as the web height is probably the web and the flange thickness combined.


cheers

 

I already used the spread sheet on that link, it gives 8.6^cm3, but I was supspicious about it, so I post the result on the link below and Ad Hoc replied that the section modulus is 7.1 cm^m3;

Is there another SM that would have this value? Would you post a link for commercial Tee' SM

http://www.boatdesign.net/forums/boat-design/aluminum-boat-help-25825-3.html

Thanks

 

The spreadsheet is correct but you need to break the section down into the rectangles, in the input field from the top 7,50,58,7 and viola you get 7124mm^3

This is becasue you are confusing the geometry and you need to subtract the flange thickness from the overall dimension to get the web height before calculating SM from the separate shapes.

ok ?

 

Mike Jones

I got it, thanks....I sent you a private message, have you recieve it?

regrds

 

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follow this link:
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