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Stress relaxation after load test

Stress relaxation after load test

Stress relaxation after load test

I read several publications about stress relaxation of welded steel structures.
It's clear that stress relaxation happens at the first load cycles.
My curiosity concern the palstic deformations that's are local.
But these local deformations could lead a little permanent deformations of the structures?
In other words, loading a welded structure inside the elastic limit (i.e. load test) could lead a minimal permanent deformations?

I didn't find publications or experimental results about this aspect


RE: Stress relaxation after load test

"Elastic limit, maximum stress or force per unit area within a solid material that can arise before the onset of permanent deformation. When stresses up to the elastic limit are removed, the material resumes its original size and shape. Stresses beyond the elastic limit cause a material to yield or flow. For such materials the elastic limit marks the end of elastic behaviour and the beginning of plastic behaviour. For most brittle materials, stresses beyond the elastic limit result in fracture with almost no plastic deformation."

Loading a welded structure inside the elastic limit, the question to your answer is no.


RE: Stress relaxation after load test

Maybe I didn't explain correctly
I'm speacking of structural steel with hgh toughness and about "local plastic deformation" due to the sum of residual stresses of welding process and stresses imposed by the load


RE: Stress relaxation after load test

Hi Andstar

Yes I think what you are saying can happen however whether the deformation post load is detectable is another matter.
A good example might be a welded pressure vessel which during load test may have local areas say on support brackets etc which go beyond the elastic limit but the codes for construction usually have safety factors such that there would be no concerns about it happening.

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

RE: Stress relaxation after load test

If any part of a structure has plastically deformed (yielded) then there will be some permanent deformation afterward.

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