Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
(OP)
All,
I'm trying to verify Battelle's structural stress method by Dong for shell elements. For a start, I'm doing a quick calc on a spreadsheet before diving into an APDL script. Is there a way to estimate or hand-calculate a value for structural stress and can membrane stress be negative as in the example provided? Of course, since membrane stress is the average value through the cross section, it should be positive. Also, is this calculation a futile effort as the Battelle Structural stress method is patented and not available outside software addons like FE-Safe/Verity?
Note, the tables are nodal forces/moments scoped using ENFOVECTORS/ENMOVECTORS in the local coordinate system.
Model:

Nodes/Elements:

Line Moments for Element 4970:

Line Forces for Element 4970:

Ref: Selvakumar, P., Hong, J.K.Hide, Robust mesh insensitive structural stress method for fatigue analysis of welded structures, Procedia Engineering, Volume 55, 2013
Thank you.
I'm trying to verify Battelle's structural stress method by Dong for shell elements. For a start, I'm doing a quick calc on a spreadsheet before diving into an APDL script. Is there a way to estimate or hand-calculate a value for structural stress and can membrane stress be negative as in the example provided? Of course, since membrane stress is the average value through the cross section, it should be positive. Also, is this calculation a futile effort as the Battelle Structural stress method is patented and not available outside software addons like FE-Safe/Verity?
Note, the tables are nodal forces/moments scoped using ENFOVECTORS/ENMOVECTORS in the local coordinate system.
Model:

Nodes/Elements:

Line Moments for Element 4970:

Line Forces for Element 4970:

Ref: Selvakumar, P., Hong, J.K.Hide, Robust mesh insensitive structural stress method for fatigue analysis of welded structures, Procedia Engineering, Volume 55, 2013
Thank you.
RE: Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
But membrane stress can be negative if the load is compressive or producing effect that is overall compressive. For example, axial compressive load on simple bar. The average stress/membrane stress will be compressive. As I see it, the remote force(-x direction as per coordinate system in other image) try to bend the square section at the welds about -y-axis and twist about the +z-axis. So the elements ( 4969 and 4970) may be in compression, if my imagination is correct. Its my guess though. You can check that by plotting min principal stress.
RE: Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
RE: Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
The elements are in
tensioncompression.When I repeat the calculation for element 4183, I get a value of 556,619 cycles for a stress ratio R = 0, which is very close to the results Dr. Dong and his team demonstrated in the original 2003 SAE completion. However, for R = -1, I have some errors in my spreadsheet. At this stage, it's just fortuity or complete idiocy.
RE: Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
Did you find any information in the book I mentioned? If you have access to/have any contact/friend who can check it in fe-safe, that will be helpful to you to benchmark your results and end your frustration.
RE: Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
RE: Line Forces and Line Moments For Battelle's Structural Stress for Fatigue
RE: Line Forces and Line Moments For Battelle's Structural Stress for Fatigue