RE: Visualizing soil stresses in soil block

[ryancwl95]

Hi,

I have 2 questions regarding the visualization of soil data using STKO post-processing.

1. Can I generate a cross-section profile in STKO post-processing to visualize the behavior within the soil body for a wide block subjected to surcharge?

2. I am interested in understanding the flow direction of water in STKO. Could you provide insights into estimating flow values and visualizing the flow direction in the post-processing stage?

Sincerely,

Ryan Chia

[kesavapraba]

Hi,
1] Yes, you can visualize the cross section by selecting the soil portion that you are interested in and showing only that portion. Please refer to the attached figure here.

2] It is not clear for me to understand the context of your query, however, you can explore "Vector Plot" if it helps.

[ryancwl95]

Hi,

1) I am not too sure what you mean by selecting the soil portion and showing only that portion. However, this is what I want to view, a cut section of the soil body (section A-A, as shown in the image attached).

Screenshot 2024-01-31 192837.png (316.7 KiB) Viewed 8842 times

2) I am interested to view the quantities of ground water flow in a soil body subjected to a loading, i.e q (m/s or m3/s) of the water caused by a difference in water pressure gradients. I have checked the vector plot, however, there is no such result available. Could there be another way to view the flow of water in the soil body during the loading analysis.

Screenshot 2024-01-31 193558.png (18.04 KiB) Viewed 8842 times

[kesavapraba]

Hi, Following are my suggestions:

1] You can select the entire front side of the cut (A-A in your attached figure) and hide the view. This will show the portion of the soil you are interested in.

2] Visualizing the flow of water in the soil body is not possible, however you can visualize the pore water pressure.

[ryancwl95]

hi,

1) what if I want to view another section which is 45degfrom section cut A-A? does this mean I need to manually hide each block to view that new section? or is there a more easier way to do so?

[kesavapraba]

Yes, you have to hide the portion and visuzalize the reminaing ones, be it any angle. You can use only hide option. No other alternative option is available as of now.

[ryancwl95]

Is it possible to have a sample script, such that when the script is being run it hides the selected elements listed in the code?

[STKO Team]

This is a simple script that selects all elements according to the position of their centroid.
You can adapt it to your needs

Code: Select all

from PyMpc import *
from PyMpc import MpcOdbVirtualResult as vr
import math

App.clearTerminal()
doc = App.postDocument()
pg = doc.activePlotGroup

# clear current selection
doc.scene.unselectAll()

# get a result and evaluate it to get a mesh
database_id = 1
db = doc.getDatabase(database_id)
U = db.getNodalResult('Displacement')
all_stages = db.getStageIDs()
last_stage = all_stages[-1]
all_steps = db.getStepIDs(last_stage)
last_step = all_steps[-1]
opt = MpcOdbVirtualResultEvaluationOptions()
opt.stage = last_stage
opt.step = last_step
field = U.evaluate(opt)
mesh = field.mesh

# select all elements according to the position of their centroid.
for ele_id, ele in mesh.elements.items():
	c = ele.computeCenter()
	# here you can implement your logic.
	# In this example I want all elements at a positive X
	if c.x > 0:
		# select this element in all plots of the current plot group
		for plot_id, plot in pg.plots.items():
			# get the selection data for this plot, or create it
			selection_data = doc.scene.plotSelection.get(plot_id, None)
			if selection_data is None:
				selection_data = MpcOdpSelectionData()
				doc.scene.plotSelection[plot_id] = selection_data
			# add this element
			selection_data.info.elements.insert(ele_id)
# done
doc.scene.updateSelectionVisualRepresentationAndGraphics()
App.updateActiveView()

[Alessandro2016]

Hello, I have browsed the above content. I would like to ask if STKO can display the drainage path of pore water pressure. Can this function be realized through PyMPC scripts or export the results to third-party software? I hope my questions can be answered by you.
With best wishes.

[STKO Team]

Try this script, read it and see if it does what you want:

Code: Select all

from PyMpc import *

# USER SETTINGS
DATABASE_ID = 1
ARROW_SCALE = 1.0

App.clearTerminal()
doc = App.postDocument()
doc.clearCustomDrawableEntities()

# get active plot group
group = doc.activePlotGroup

# allocate a shape for plotting
vrep = FxShape()
vrep_edge = None

# process all plots in this plot group
for _, plot in group.plots.items():
	# get source DB, stage and step indices
	db = doc.getDatabase(plot.plotData.db)
	stage = plot.plotData.stage
	step = plot.plotData.step
	# get result
	P = db.getNodalResult('Pressure')
	# evaluate it
	opt = MpcOdbVirtualResultEvaluationOptions()
	opt.stage = stage
	opt.step = step
	PField = P.evaluate(opt)
	# now we have a scalar field of the water pore pressure.
	# we can compute its spatial derivative DP = dP/dX (a vector field)
	# -DP will give the path
	N = Math.vec() # pre-allocate a vector for shape functions
	dN = Math.mat() # pre-allocate a matrix for shape function local derivatives
	J = Math.mat() # pre-allocate a matrix for jacobian
	for _, ele in PField.mesh.elements.items():
		# compute the location of the center in natural coords
		p0 = MpcIntegrationPoint(0.0, 0.0)
		for ip in ele.integrationRule.integrationPoints:
			p0.x += ip.x
			p0.y += ip.y
			p0.w += ip.w
		p0.x /= ele.numberOfIntegrationPoints()
		p0.y /= ele.numberOfIntegrationPoints()
		# evaluate local derivatives and jacobian at center
		ele.jacobianAt(p0, dN, J)
		# handle the 2D case
		if J.cols == 2:
			dN0 = dN.col(0)
			dN1 = dN.col(1)
			dN = Math.mat(dN.rows, 3, 0.0)
			for i in range(dN.rows):
				dN[i, 0] = dN0[i]
				dN[i, 1] = dN1[i]
			J0 = J.col(0)
			J1 = J.col(1)
			J = Math.mat(3,3, 0.0)
			for i in range(3):
				J[i, 0] = J0[i]
				J[i, 1] = J1[i]
			J[2, 2] = 1.0
		# compute cartesian derivatives
		dNdX = dN * J.inverse()
		# collect pressure values at the nodes
		PNodal = Math.vec([ PField[MpcOdbResultField.node(node.id), 0] for node in ele.nodes ])
		# compute the gradient of the scalar Pressure at the center
		dPdX = Math.vec3(*(dNdX.transpose() * PNodal))
		dPdX *= -1.0 # negate it, we want the direction of decreasing pressure
		# update VREP
		center = ele.computeCenter()
		length = dPdX.norm() * ARROW_SCALE
		axis = dPdX.normalized()
		radius_ratio = 0.04
		num_seg = 6
		double_arrow = False
		vrep_arrow = FxShapeFactory.arrowLine(center, axis, length, radius_ratio, num_seg, double_arrow)
		if vrep_edge is None:
			vrep_edge = vrep_arrow
		else:
			vrep_edge.merge(vrep_arrow)

# add the VREP to the scene
vrep.edges.append(vrep_edge)
vrep_material = FxMaterial()
vrep_material.edgeColor = FxColor(.6,0,0) # R,G,B in range[0,1]
vrep_material.lineWidth = 2.0
vrep.material = vrep_material
doc.addCustomDrawableEntity(vrep)
App.updateActiveView()