Hi Rodolfo,

In ABAQUS, for instance, you can use the "Create Predefined Field" option in the "Load" module to apply an initial stress pattern to the desired region of your steel tube in order to resemble the residual stresses.   Using this option, you can directly define the initial stress pattern in your model  OR  you can import the stresses from the results of another analysis in which you have obtained the residual stress pattern. 

There are two important issues here:

1. First you should find a proper initial stress pattern for your specimen from the previously reported residual stress measurements available in the literature.  If you want, there are also interesting methods which you can use to obtain the residual stress pattern of your specimen yourself.

2. After applying the initial stress pattern in ABAQUS, you should define an "empty" analysis step, in which ABAQUS will try to reach to a self-equilibrium state of stress.  In other words, you need an intermediate step between the initiation of the analysis and the step at which you will apply your uniaxial compression load.

It is worth noting that some researchers use Temperature Loading to mimic residual stresses instead of applying a direct initial stress pattern.

Hope this helps.

Hi Rodolfo,

In ABAQUS, for instance, you can use the "Create Predefined Field" option in the "Load" module to apply an initial stress pattern to the desired region of your steel tube in order to resemble the residual stresses.   Using this option, you can directly define the initial stress pattern in your model  OR  you can import the stresses from the results of another analysis in which you have obtained the residual stress pattern. 

There are two important issues here:

1. First you should find a proper initial stress pattern for your specimen from the previously reported residual stress measurements available in the literature.  If you want, there are also interesting methods which you can use to obtain the residual stress pattern of your specimen yourself.

2. After applying the initial stress pattern in ABAQUS, you should define an "empty" analysis step, in which ABAQUS will try to reach to a self-equilibrium state of stress.  In other words, you need an intermediate step between the initiation of the analysis and the step at which you will apply your uniaxial compression load.

It is worth noting that some researchers use Temperature Loading to mimic residual stresses instead of applying a direct initial stress pattern.

Hope this helps.

The challenge will be to quantify the residual stresses in the first place in order to model them properly. I guess you already have experimental data at hand to do some benchmarking?

Thank you for your responses. Unfortunately, I am not doing it in Abaqus but using our developed nonlinear FEM program. I find your suggestions very helpful. It is reasonable that in lieu of explicitly modeling residual stress, we just reduced the yield strength of steel?