Data Files for “SimpleBBM” Example

specimen.dat

; Clear the model state and create a domain in which all of the 
; rigid blocks exist
model new
model domain extent -10 10

; Create a cylindrical geometry set that is 2.5 times as tall as 
; wide for the UCS and direct tension test
geometry set 'specimen' 
[specRadius = 1.5]
[specHeight = 7.0]
geometry generate cylinder base 0 0 [-specHeight/2.0] radius [specRadius] ...
                  height [specHeight] axis 0 0 1 resolution 0.4

; Create the rigid blocks as tetrahedra. This command meshes the 
; geometry set, creating rigid blocks. 
rblock construct from-geometry 'specimen' maximum-edge 0.4 

; Scale the rigid blocks so that they are originally overlapping. This is
; required for the contact location to be correct when bonding. When the bond
; method is called the contact location is only incrementally updated.
rblock scale relative 1.01

; Erode the rigid blocks, introducing rounding. This allows one to cull the 
; numerous edge-edge and vertex-vertex contacts that do not contribute to the 
; model response. This may fail at times so it is a good idea to use the 
; skip-errors keyword
rblock erode relative skip-errors 0.05

; Group the top and platens which are fixed chunks of rigid blocks. 
rblock group 'top-platen' range position-z [specHeight/2.0 - 0.3] 10
rblock group 'bottom-platen' range position-z [0.3 - specHeight/2.0] -10

; Set the damping and density
rblock attribute density 2650 damp 0.7 

; Fish symbol for the bond tensile strength 
[tensileStrength = 4.7e6]

; Ratio cohesive to tensile strength
[cohesionFactor = 2.4]

; Target elastic modulus to put into the bonds
[emod = 7.25e10] 

; Specify the softbond model properties. 
contact cmat default model softbond method deformability emod [emod] ...
                           kratio 2.0 ...
                           property sb_ten [tensileStrength] ...
                           sb_coh [cohesionFactor*tensileStrength] ...
                           sb_fa 30.0 fric 0.5 sb_mode 1
                      
; Create the contacts and bond them. Note that no softening is used in this 
; example so the softbond contacts act essentially as parallel bond contacts 
; except that there is only 1 set of stiffnesses and the shear stress is not 
; nulled if shear failure occurs. 
model clean all
contact method bond 

; Make the platen contacts have the null contact model. This is to reduce 
; computation and to ensure that they do not contribute to the stress 
; computation. The match keyword is used to specify that contacts fall within
; the range if both of the ends have the specified group. 
contact model null range group 'top-platen' match 2
contact model null range group 'bottom-platen' match 2

; Inhibit the contacts that are not bonded. This is VERY important for 
; efficient bonded ; block models. This means that the force-displacement law
; for edge-edge and vertex-vertex contacts is skipped along with updating the
; contact positions. You can compare the results and runtimes with and without
; the vertex-vertex and edge-edge contacts. If in small strain these contacts
; can actually be deleted with the contact delete command and contact 
; detection can be turned off. 
contact inhibit range contact gap 0 100

; Fix the velocity and spin of the top and bottom platens
rblock fix vel spin range group 'top-platen' 
rblock fix vel spin range group 'bottom-platen' 

; Make maps of the rigid blocks in the platens
[topMap = rblock.groupmap('top-platen')]
[botMap = rblock.groupmap('bottom-platen')]

; Define a FISH function to compute the stress and elastic modulus. 
; Histories of these quantities will be kept for display. 
fish define stress
    local stressTop = 0.0
    local stressBot = 0.0
    strain = 0.0
    loop foreach b topMap
        stressTop = stressTop + math.abs(rblock.force.contact(b,3))
        strain = 2.*math.abs(rblock.disp(b,3))
    endloop
    loop foreach b botMap
        stressBot = stressBot + math.abs(rblock.force.contact(b,3))
    endloop
    local st = (stressTop + stressBot)/(2.0 * math.pi*specRadius^2);
    strain = strain/specHeight
    if strain > 0
        modulus = st / strain
    endif
    stress = st
end
fish history @stress
fish history @strain
fish history @modulus

; Set up a FISH halt to end cycling when the stress is 80% of the maximum
[maxStress = 0.0]
[peakPercentage = 0.8]
fish define halt
    halt = 0
    maxStress = math.max(maxStress,stress)
    if stress < peakPercentage * maxStress
        halt = 1
    endif
end

; Register for fragment computation
fragment register rblock-rblock

; Save the specimen
model save 'specimen'
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tests.dat

;************************************************************
; UCS TEST
;************************************************************
; Restore the specimen and run the UCS 
model restore 'specimen'

; Positive velocity means compression - this will be applied to the top 
; and bottom platens
[nvel = 1.0]

; Apply the velocities to the rigid blocks so that 
; the model isn't shocked by the initial velocity on the platens. 
rblock attribute velocity-z 0.0 gradient 0 0 [-2.0 * nvel / specHeight]

; Set the platen velocities after assigning the velocities throughout
; the model. 
rblock attribute velocity-z [nvel] range group 'bottom-platen'
rblock attribute velocity-z [-1*nvel] range group 'top-platen'

; Run the UCS test
model solve fish-halt @halt cycles 1000000

; Compute fragments
fragment compute

; Save the UCS test
model save 'ucs'

;************************************************************
; DIRECT TENSION TEST
;************************************************************
; Restore the specimen and run the UCS 
model restore 'specimen'

; Negative velocity means tension - this will be applied to the top 
; and bottom platens
[nvel = -0.1]

; Apply the velocities to the rigid blocks so that 
; the model isn't shocked by the initial velocity on the platens. 
rblock attribute velocity-z 0.0 gradient 0 0 [-2.0 * nvel / specHeight]

; Set the platen velocities after assigning the velocities throughout
; the model. 
rblock attribute velocity-z [nvel] range group 'bottom-platen'
rblock attribute velocity-z [-1*nvel] range group 'top-platen'

; Run the direct tension test
model solve fish-halt @halt cycles 1000000

; Compute fragments
fragment compute

; Save the tension test
model save 'tension'
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specimen.dat

; Clear the model state and create a domain in which all of the 
; rigid blocks exist
model new
model domain extent -10 10

; Create a cube of material for the UCS and direct tension test
geometry set 'specimen' 
[specWidth = 7.0]
[specHeight = 7.0]
geometry generate box [-specWidth/2.0] [specWidth/2.0] ...
                      [-specHeight/2.0] [specHeight/2.0] 

; Create the rigid blocks as tetrahedra. This command meshes the 
; geometry set, creating rigid blocks. 
rblock construct from-geometry 'specimen' maximum-edge 0.2 

; Scale the rigid blocks so that they are originally overlapping. This is
; required for the contact location to be correct when bonding. When the bond
; method is called the contact location is only incrementally updated.
rblock scale relative 1.01

; Erode the rigid blocks, introducing rounding. This allows one to cull the 
; numerous edge-edge and vertex-vertex contacts that do not contribute to the 
; model response. This may fail at times so it is a good idea to use the 
; skip-errors keyword
rblock erode relative skip-errors 0.05

; Group the top and platens which are fixed chunks of rigid blocks. 
rblock group 'top-platen' range position-y [specHeight/2.0 - 0.2] 10
rblock group 'bottom-platen' range position-y [0.2 - specHeight/2.0] -10

; Set the damping and density
rblock attribute density 2650 damp 0.7 

; Fish symbol for the bond tensile strength 
[tensileStrength = 2e7]

; Ratio cohesive to tensile strength
[cohesionFactor = 3.]

; Target elastic modulus to put into the bonds
[emod = 1.95e11] 

; Specify the softbond model properties. 
contact cmat default model softbond   method deformability emod [emod] ...
                           kratio 2.0 ...
                           property sb_ten [tensileStrength] ...
                           sb_coh [cohesionFactor*tensileStrength] ...
                           sb_fa 30.0 fric 0.5 sb_mode 1
                      
; Create the contacts and bond them. Note that no softening is used in this 
; example so the softbond contacts act essentially as parallel bond contacts 
; except that there is only 1 set of stiffnesses and the shear stress is not
; nulled if shear failure occurs. 
model clean all
contact method bond 

; Make the platen contacts have the null contact model. This is to reduce 
; computation and to ensure that they do not contribute to the stress 
; computation. The match keyword is used to specify that contacts fall within
; the range if both of the ends have the specified group. 
contact model null range group 'top-platen' match 2
contact model null range group 'bottom-platen' match 2

; Make the contacts with the platen rigid blocks have infinite strength
contact property sb_ten 1e10 sb_coh 1e10 range group 'top-platen' match 1
contact property sb_ten 1e10 sb_coh 1e10 range group 'bottom-platen' match 1

; Inhibit the contacts that are not bonded. This is VERY important for 
; efficient bonded block models. This means that the force-displacement law 
; for vertex-vertex contacts is skipped along with updating the contact 
; positions. You can compare the results and runtimes with and without the 
; vertex-vertex contacts. If in small strain these contacts can actually be 
; deleted with the contact delete command and contact detection can be 
; turned off. 
contact inhibit range contact gap 0 100

; Fix the y-velocity of the top and bottom platens
rblock fix velocity-y spin range group 'top-platen' 
rblock fix velocity-y spin range group 'bottom-platen' 

; Make maps of the rigid blocks in the platens
[topMap = rblock.groupmap('top-platen')]
[botMap = rblock.groupmap('bottom-platen')]

; Define a FISH function to compute the stress and elastic modulus. 
; Histories of these quantities will be kept for display. 
fish define stress
    local stressTop = 0.0
    local stressBot = 0.0
    strain = 0.0
    loop foreach b topMap
        stressTop = stressTop + math.abs(rblock.force.contact(b,2))
        strain = 2.*math.abs(rblock.disp(b,2))
    endloop
    loop foreach b botMap
        stressBot = stressBot + math.abs(rblock.force.contact(b,2))
    endloop
    local st = (stressTop + stressBot)/2.0/specWidth
    strain = strain/specHeight
    if strain > 0
        modulus = st / strain
    endif
    stress = st
end
fish history @stress
fish history @strain
fish history @modulus
history interval 1

; Set up a FISH halt to end cycling when the stress is 80% of the maximum
[maxStress = 0.0]
[peakPercentage = 0.8]
fish define halt
    halt = 0
    maxStress = math.max(maxStress,stress)
    if stress < peakPercentage * maxStress
        halt = 1
    endif
end

; Register for fragment computation
fragment register rblock-rblock

; Save the specimen
model save 'specimen'
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tests.dat

;************************************************************
; UCS TEST
;************************************************************
; Restore the specimen and run the UCS 
model restore 'specimen'
; Positive velocity means compression - this will be applied to the top 
; and bottom platens
[nvel = 0.5]

; Apply the velocities to the rigid blocks so that 
; the model isn't shocked by the initial velocity on the platens. 
rblock attribute velocity-y 0.0 gradient 0 [-2.0 * nvel / specHeight]

; Set the platen velocities after assigning the velocities throughout
; the model. 
rblock attribute velocity-y [nvel] range group 'bottom-platen'
rblock attribute velocity-y [-1*nvel] range group 'top-platen'

; Run the UCS test
model solve fish-halt @halt cycles 1000000

; Compute fragments
fragment compute

; Save the UCS test
model save 'ucs'

;************************************************************
; DIRECT TENSION TEST
;************************************************************
; Restore the specimen and run the UCS 
model restore 'specimen'

; Negative velocity means tension - this will be applied to the top 
; and bottom platens
[nvel = -0.05]

; Apply the velocities to the rigid blocks so that 
; the model isn't shocked by the initial velocity on the platens. 
rblock attribute velocity-y 0.0 gradient 0 [-2.0 * nvel / specHeight]

; Set the platen velocities after assigning the velocities throughout
; the model. 
rblock attribute velocity-y [nvel] range group 'bottom-platen'
rblock attribute velocity-y [-1*nvel] range group 'top-platen'

; Run the direct tension test
model solve fish-halt @halt cycles 1000000

; Compute fragments
fragment compute

; Save the tension test
model save 'tension'
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