Calculation of fillet weld cross sectional area

Date 10-13-2015 17:48

Hi all, the attached snapshot has been taken from the CSWIP course book. My question is regarding calculation of fillet weld cross sectional area when double side fillet weld is used in the extreme right figure( last figure). I calculated it and found it 50 mm square but here it is 72 mm square. How is this calculated? I simply calculate the leg lengths from the given throat by formula

Leg length= 1.414141 * Throat thickness

Area= 1/2 * leg length square=25 for one triangle.

Adding both i get 50.

How 72 is possible?

Thanx all in advance.

Attachment: Untitled.jpg (177k)

By waqasmalik (**)

Date 10-14-2015 13:45

803056.
The attached snapshot is from TWI. Three types of welds have been shown with equal throats which is 10 mm. In last figure where there is double side fillet weld but same accumulative throat 5+ 5= 10 mm.

Leg length= 1.414*5=7.07 and squaring it gives 50 mm square. ( Your formula made it short for me, thank you). I calculated by solving triangles. Both techniques gives the same result then how does 72 appears there?

Attachment: Untitled.png (91k)

By 803056

Date 10-14-2015 14:21 Edited 10-14-2015 14:37

I think there is an error in their calculations. My calculations are in agreement with yours.

I've played with their numbers and do not see how they came up with 72. The closest I got to their number was 70.7 and that was by totally screwing up the calculation. ((5x5)x1.414)x2) = 70.2, still not 72 as per their incorrect value.

I seem to remember this question being asked a few years ago. It hasn't changed during the intervening years. Maybe they should review their text. After all, a human was involved in writing the text and we humans do tend to make mistakes now and again.

Al

By waqasmalik (**)

Date 10-14-2015 17:28

803056.

For single bevel ( angle of 60 degree) butt welded T joint + Fillet weld outside, same throat thickness, weld area is calculated as 57.7 mm square.

For double bevel ( each angle of 45 degrees) butt welded T joint with no fillet outside, throat thickness of (5+5)10, weld area is calculated as 25 mm square.

Weld areas for same throat thickness of 10 mm are summarized as

1) Single side Fillet welded T joint= 100 mm square.

2)Single bevel butt welded T joint + fillet weld outside=57.7

3) Single bevel butt welded T joint with no fillet= 50 mm square.

4) Double side fillet weld = 50 mm square.

5) Double bevel butt welded T joint with no fillet= 25 mm square.

Respected sir, What will the strength of all these welds? i assume because they all have same throat so load carrying capability will be same.

Also will the residual tensile stresses decrease with decrease in weld volume?

Which one of the above welds will have highest resistance to cracking if crackable material is there ?

Thank you in advance, i like to read you.

Waqas