【PFC6.0】三维Cluster模拟混合料混凝土

lobby 2023年4月27日浏览：1845 评论：4 收藏：14

0 引言

对于含集料混凝土，集料强度相对于水泥强度高很多，所以一般不会考虑到集料的可破坏性。所以大部分情况下，使用clump来模拟集料混凝土也就够了。但是在一些特别的受集中力的工况下，集料的破坏也不少见，这种情况就需要去考虑集料的破坏了。

本文基于已有的研究成果，提出一种以cluster为集料颗粒的混凝土成样方式，并用单轴实验来进行测试。

1 成样

对于混凝土，集料一般不是很多，这里在空间中生成松散的ball代替集料。

model newdef par    width=2    height=width*2        rdmin=0.2    rdmax=0.4        poro=0.8end@par

domain extent [-width*2.0] [width*2.0] [-width*2.0] [width*2.0] ...        [-height*2.0] [height*2.0]model random 10001

wall generate box [-width*0.5] [width*0.5] [-width*0.5] [width*0.5] ...            [-height*0.5] [height*0.5] expand 1.5ball distribute porosity @poro radius [rdmin] [rdmax] box ...    [-width*0.5] [width*0.5] [-width*0.5] [width*0.5] [-height*0.5] [height*0.5] ball attribute density 2e3 damp 0.7contact cmat default model linear method deform emod 100e6 kratio 1.5model cycle 2000 calm 50ball property "fric" 0.5model solvemodel save "sample"

结果如图所示：

【PFC6.0】三维Cluster模拟混合料混凝土的图1

2 clump替换

这里还是用的上一个案例【【PFC6.0】三维Cluster碎石三轴模拟】的clump模板，这个工况对模板的要求不高，可以自行生成模板。

model restore "sample"

def importTemplate    loop n(1,4)        stlName="Rock"+string(n)        fileName="Template\\"+stlName+".p3clp"        command            clump template import @fileName name @stlName        endcommand    endloopend@importTemplate

def GetTemplateName    rd=math.random.uniform    if rd<0.25 then        GetTemplateName="Rock1"    else if rd<0.5 then         GetTemplateName="Rock2"    else if rd<0.75 then         GetTemplateName="Rock3"    else         GetTemplateName="Rock4"    endifend

[clump_count=1]def tihuan    loop foreach bp ball.list        x_pos   = ball.pos(bp,1)        y_pos   = ball.pos(bp,2)        z_pos   = ball.pos(bp,3)        bvol = (4/3.0)*math.pi*ball.radius(bp)^3           template_name=GetTemplateName        ball.delete(bp)                      angle= math.random.uniform*180         axis_x=math.random.uniform-0.5        axis_y=math.random.uniform-0.5        axis_z=math.random.uniform-0.5        axis=vector(axis_x,axis_y,axis_z)                        command                            clump replicate id @clump_count name @template_name  ...                            pos-x @x_pos pos-y @y_pos pos-z @z_pos  ...                           volume @bvol  angle @angle axis @axis            clump group  @template_name range id @clump_count        endcommand          clump_count+=1    endloopend@tihuan

clump attribute density 2e3 damp 0.7

cmat default type pebble-facet model linear method deform emod 1000e6 kratio 1.5clump attribute density 2.3e3 damp 0.7





[yasuo_time=5]

wall deletewall generate box [-width] [width] [-width] [width] ...    [-height] [height]  wall attribute velocity-z [(height*0.5)/yasuo_time] range id 1wall attribute velocity-z [-(height*0.5)/yasuo_time] range id 2wall attribute velocity-x [(width*0.5)/yasuo_time] range id 3wall attribute velocity-x [-(width*0.5)/yasuo_time] range id 4 wall attribute velocity-y [(width*0.5)/yasuo_time] range id 5wall attribute velocity-y [-width*0.5/yasuo_time] range id 6solve time [yasuo_time*0.3] calm 10 solve time [yasuo_time*0.7]wall attribute velocity 0 0 0

model solve 

model save "tihuan_clump"

3 集料区域获取

这里我们把集料的范围进行提取，这里用的是clump export geometry方法。把四个clump形状提取出四个clump geometry。

model restore "tihuan_clump"

geometry delete

clump export geometry set "Rock1" range group "Rock1"clump export geometry set "Rock2" range group "Rock2"clump export geometry set "Rock3" range group "Rock3"clump export geometry set "Rock4" range group "Rock4"



model save "GeoOut"

如图：

【PFC6.0】三维Cluster模拟混合料混凝土的图2

4 重生成细颗粒

这里需要把之前的颗粒删除，然后重新生成细颗粒，方便在后面把geometry范围内的颗粒聚合成cluster

model restore "GeoOut"clump delete

[rdmin=0.04][rdmax=0.06][poro=0.3]ball distribute porosity @poro radius [rdmin] [rdmax] box ...    [-width*0.5] [width*0.5] [-width*0.5] [width*0.5] [-height*0.5] [height*0.5] ball attribute density 2e3 damp 0.7model cycle 2000 calm 50ball property "fric" 0.5model solvemodel save "re_sample"

如图：

【PFC6.0】三维Cluster模拟混合料混凝土的图3

5 加胶结

这里将不同geometry范围的颗粒进行胶结。

model restore "re_sample"ball group "Rock1" range geometry-space "Rock1" inside ball group "Rock2" range geometry-space "Rock2" inside ball group "Rock3" range geometry-space "Rock3" inside ball group "Rock4" range geometry-space "Rock4" inside 





cmat default model linearpbond method deform emod 1e9 kratio 1.5 pb_deform emod 1e9 kratio 1.5 ...        property pb_coh 10e6 pb_ten 10e6 pb_fa 50 fric 0.1 lin_mode 1cmat add 1 model linear method deform emod 10e9 kratio 1.5 ...        property  lin_mode 1  range contact type "ball-facet" cmat add 2 model linearpbond method deform emod 5e9 kratio 1.5 pb_deform emod 5e9 kratio 1.5 ...        property pb_coh 15e6 pb_ten 15e6 pb_fa 50 fric 0.1 lin_mode 1  range group "Rock1" match 2cmat add 3 model linearpbond method deform emod 6e9 kratio 1.5 pb_deform emod 6e9 kratio 1.5 ...        property pb_coh 18e6 pb_ten 18e6 pb_fa 50 fric 0.1 lin_mode 1  range group "Rock2" match 2cmat add 4 model linearpbond method deform emod 7e9 kratio 1.5 pb_deform emod 7e9 kratio 1.5 ...        property pb_coh 20e6 pb_ten 20e6 pb_fa 50 fric 0.1 lin_mode 1  range group "Rock3" match 2cmat add 5 model linearpbond method deform emod 8e9 kratio 1.5 pb_deform emod 8e9 kratio 1.5 ...        property pb_coh 22e6 pb_ten 22e6 pb_fa 50 fric 0.1 lin_mode 1  range group "Rock4" match 2        cmat apply

model clean

contact method bond gap [rdmin]

contact property lin_force 0 0 0

ball attribute force-contact 0 0 0 moment-contact 0 0 0model calm

model cycle 1

model solve

model save "jiaojie"

如图：

【PFC6.0】三维Cluster模拟混合料混凝土的图4

仅显示集料颗粒看一下：

【PFC6.0】三维Cluster模拟混合料混凝土的图5

显示参数做个剖面，也能比较好的看出效果：

【PFC6.0】三维Cluster模拟混合料混凝土的图6

6 加载

model restore "jiaojie"model mechanical time-total 0wall delete walls range id 3 6 ball attribute displacement multiply 0def wall_init    wpUp=wall.find(2)    wpDown=wall.find(1)end@wall_init



[IZ0=wall.pos.z(wpUp)-wall.pos.z(wpDown)]

[strainrate=0.01]wall attribute vel-z [-IZ0*strainrate*0.5] range id 2wall attribute vel-z [IZ0*strainrate*0.5] range id 1

def jiance    whilestepping    wzss=(wall.force.contact.z(wpUp)-wall.force.contact.z(wpDown))*0.5/(width*width)    wlz=wall.pos.z(wpUp)-wall.pos.z(wpDown)end

[final_time=2e-2/strainrate][baocunpinlv=final_time/40.0][time_record=-100][count=0]def savefile    time=mech.time.total    wezz=(wlz-IZ0)/IZ0    if time-time_record >= baocunpinlv then        filename=string.build("jieguo_%1",count)        command           model save @filename        endcommand        time_record=time        count +=1    endifend

fish callback add @savefile -1.0

program call "fracture.p3fis"

history deletehistory id 1 @wzsshistory id 2 @wezz@track_initmodel solve time @final_time

model save "result"

首先看一下整体情况：

【PFC6.0】三维Cluster模拟混合料混凝土的图7

基本上是一个标准的胶结材料单轴的力学特性。

那再看点好玩的东西。

写了一个简单的接触分组代码，可以筛选出当前接触中的强接触，分界的阈值时平均力的1.5倍。

首先单轴工况下，竖向接触受力，横向接触基本不受力。所以这里认为横向接触都是弱接触。强弱的区分只考虑在竖向接触中

model restore "jieguo_6"

def GetAverageForce    allForce=0    num=0    loop foreach ct contact.list("ball-ball")        forceVec=math.unit(contact.normal(ct))        dip=math.dip.from.normal(forceVec)        if dip<math.pi*0.25 | dip>math.pi*0.75 then                    allForce+=math.mag(contact.force.global(ct))            num+=1            contact.group(ct,"dirt")="shuxiang"        else            contact.group(ct,"dirt")="hengxiang"            contact.group(ct,"mag")="ruo"        endif    endloop    AverageForce=allForce/float(num)end@GetAverageForce



def ContactGroup    test_num=0    loop foreach ct contact.list("ball-ball")        if contact.group(ct,"dirt")="hengxiang" then            continue        endif        if math.mag(contact.force.global(ct))> AverageForce*1.5 then            contact.group(ct,"mag")="qiang"        else             contact.group(ct,"mag")="ruo"        endif        test_num+=1    endloopend@ContactGroup