Highly stressed volume approach in ANSYS apdl

[BTHS]

Hi all at Eng-tips

I i'm getting better and better at the apdl-language, even though i still think its a bit daunting. I've started to work on a technique to extract the highly stressed volume in a component for fatigue life assessment. In short, the highly stressed volume of the component (minimum ∽95* maximum of 1.st principal stress ) should (i'm going to investigate this further) correlate well with the fatigue strength of the component. (R. Kuegel first described the method as far as i know).

The code is currently as follows:

!Select Named selection
cmsel,s,Area1,node

!Get Maximum pricipal stress in selection and the number of the stressed node
NSORT,S,1,0,0,1
*GET,NS_SMAX,SORT,,MAX
*GET,NS_NMAX,SORT,,IMAX

!Select nodes that has a stress of at least 0.9*NS_SMAX
nsel,s,s,1,0.9*NS_SMAX
!Select elements that contain at least one of the selected nodes 
esln,r,0,all

!Get number of selected nodes
*get,n_elem,elem,,count

!State variables
ENUM=0
tot_vol=0

!Sum up the volume of elements
*do,i,1,n_elem
ENUM=elnext(ENUM)
*get,el_vol,elem,enum,volu
tot_vol = tot_vol+el_vol
*enddo

And the following nodes is selected and calculated the volume of:

The current methods accuracy is highly dependent on the mesh size. To improve performance some form of interpolation is needed.

Any questions or ideas for improvement are very welcome

Best, BTHS