# yade-users team mailing list archive

## Re: [Question #696060]: How to make some stress plates consist of 3 circles (that have radius gradually (0.5, 1, 2)?

```Question #696060 on Yade changed:

Jan Stránský proposed the following answer:
Ok, now it is clear what you want - measure stress at certain point and certain time :-)
Then, if you measure it in circles or whatever shape, how often etc. is easy extension.

First of all, in the Discrete element method, everything is discrete, i.e. you have just forces, no stress.
You can somehow convert forces to stress. Here, you should know what you want and how you want to calculate it (!), what approach is suitable, which not....

Some brainstorming of possible solutions:
- select "bottom spheres" and estimate the plate stress from the stresses of these spheres
- discretize the bottom plate with more fine mesh and then you can measure the stress from the forces acting on the smaller "elements"
- leave one big plate, but estimate the stress from "nearby" interactions.

A very scientific approach would be taking all of them and compare them
:-)

The last option seems to me as the for now easiest approach and also a nice approach in general.
something like:
###
##Make a floor
bottom = wall((0,0,-1.5),axis=2)
O.bodies.append(bottom)

def getBottomStress(point):
interactions = bottom.intrs() # get all bottom interactions
interactions = [i for i in interactions if (i.geom.contactPoint-point).norm() < limitDistance] # filtering out far away points
cps = [i.geom.contactPoint for i in interactions] # contact points
fs = [i.phys.normalForce + i.phys.shearForce for i in interactions] # forces
stress = somehowConvertForcesAndContactPointsToStress(fs,cps) # here you need to know what you want
return stress

# some running
stress34 = getBottomStress((3,4,0))
###

cheers
Jan

--

```