Stress Linearization.

[Saad12]

Hi,

I am performing structural hot spot stress analysis on 2D butt welded profile with thickness step. I need to verify the hot spot stress calculated for this analysis using stress linearization. I know I have to integrate normal stress along the thickness of weld but I am now sure exactly how the membrane and bending stresses would be calculated. Do I need to sum up stresses throughout the thickness to get membrane stress or till certain limit of thickness? Same for the bending stress? Picture is attached for reference. Am I missing somewhere? Please help me in this regard.

Thanks...

 

[desertfox]

Hi Saad12

I am wondering why the weld is subject to bending? All I can see is two faint arrows which suggest the weld is in tension, can you please provide a clearer diagram of how the weld is loaded.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Saad12]

Hi,

It is actually a butt welded specimen with different thickness bases metals and subjected to fatigue loading. Both ends were clamped with load applied only on the side having thicker base material. Since I am determining hot spot stress, linear elastic assumption is fine for me.

 

[desertfox]

Hi Saad

The weld might well be subject to fatigue however I cannot see the fatigue loading because you provide no details of it, please show a diagram of where the loads act on the weld and there direction please. It appears to me the butt weld is loaded in tension only but the loading could be varying which would cause fatigue but where are forces that put the weld in bending?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Saad12]

Hi,
It is something like that. Bending is coming mostly from the thickness variation between base materials of butt weld. I calculated hot spot stress at thickness step using linear extrapolation rule but results are not good because extrapolation rule does not consider effects of thickness step. So, I need to do stress linearization to find bending and membrane stress to verify the results. Thanks.

 

[desertfox]

Hi Saad12

This may help but I’m not sure:-

https://www.efatigue.com/training/Welds_Advanced_Methods.pdf

All my weld designs were based on hand calculations and rules of thumb

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Saad12]

Hi,

Thanks for sharing. I was looking for something similar to this:

But I am not sure how sigma n1 and sigma n2 are determined along the linearized normal stress distribution in the weld toe plane. That was a bit confusing. Like in the following picture as well. I am talking about end points of line F.

Thanks.