Welded lug to Steel Floor - Weld Computation.

[truckdesigner]

In normal circumstances we specify a Complete Penetration Butt Weld with this type of thing, but I am investigating in another instance simply specifying a 6 or 8 mm fillet weld instead.

I have attached a computation of the scenario. Could someone please take a look at it and offer me any advice, confirm that it is correct etc.

Any advice greatly appreciated.


Regards.

 

[unclesyd]

Here is a link to an upside down one as I can't find the link to the bottom up lug.

http://www.pdhonline.org/courses/s106/s106.pdf

 

[chicopee]

You forgot the shear calculation from Fh at the weld. Your Fr value is not right as it should include the max tensile stress from tensile force and bending moment and the shear value from Fh.

 

[desertfox]

Hi Truckdesigner

Have a look at this site:-

http://www.roymech.co.uk/Useful_Tables/Form/Weld_strength.html#Design_St

desertfox

 

[desertfox]

Hi again

I did a quick calculation using the Roymech site I posted previously and found that your 6mm weld will fail.
I used the table of "bracket weld subject to bending and direct stresses" cases 1 and 3 and the formula for stresses in the weld at the far right of the table.
I get a resultant stress of 484N/mm^2 and compared this with the design strength of fillet welds which appears to have a maximum of 280N/mm^2 depending on material grade.

desertfox

 

[desertfox]

Hi Again

I also noticed that in your calculation that you have used the area of 30000mm^2 then after dividing it into the loads on your lugs,then you've compared those values with a safe load per unit length, so the values you're comparing have different units ie:-

kN/mm^2 and kN/mm which cannot be correct.

desertfox