Learning Forum

[elhamasadi]

I have a sheet plate which suffers from welding residual stresses and is exposed to transient pressure load (2 steps, a triangular profile). The problem is that once the residual stresses are present (modeled using INISTATE command), changing the impact duration does not affect the structural deformations! As far as I know, the impact time being smaller or greater than the structure's natural period must affect the solution results.

Could anyone help me through this, please?

Here is the sample INISTATE command I use to apply tensile and compressive initial stresses:

###############################################

SOLU

ANTYPE,0

NLGEOM, 1

PSTRES, 1

E=70e9

Sy=194.79 !! HAZ yield stress 

Sc=32.2715

St=16.77

!! applying compression initial stress on plate

NSEL,S,LOC,X,0,1200

NSEL,R,LOC,Y,0,123.7

NSEL,R,LOC,Z,0,8

ESLN,S

INISTATE,SET,CSYS,-2

INISTATE,SET,DTYP,Stress

INISTATE,DEFINE,ALL, , , ,-Sc, , , , ,

Allsel, all

[Ashish Khemka]

When is the impact taking place? Does it happen after the effect of the initial state is relaxed (say a bar elongated in the initial state is relaxed and then the impact happens) or does it happen at the same time when the initial condition is applied?

Reards Ashish Khemka

[elhamasadi]

In the Mechanical environment, I write a command file as indicated before and apply the residual stress which happens at the same time when the initial condition is applied.
My model has welding-related issues, and it undergoes transient impact pressure loads.
Regards Elham Asadi

[elhamasadi]

Hi I tried to apply the INISTATE command on "all " load steps and received this error:
"INISTATE data cannot be edited after the first load step."
What are the causes? Is there any solution in this regard?

[Ashish Khemka]

INISTATE can be used at the start of 1st load step only.

Regards Ashish Khemka

[elhamasadi]

SO do you know any other methods that I could apply the residual stresses on all steps?