7.5. 级配颗粒堆积

前述例子介绍了单粒径颗粒的堆积，包括单一形状（ 颗粒堆积 ）和多个形状（ 混合颗粒堆积 ）。本算例演示用一个砂颗粒形状模板（参考 颗粒对象 ）生成级配颗粒进行堆积（ 图 7.6 ）。

图 7.6 均匀级配砂颗粒堆积

相对前述例子，只需要在生成颗粒是把缩放系数数组考虑进来即可，其它脚本保持不变，以下为具体脚本。

7.5.1. 基本堆积脚本

以下脚本和上一个例子基本保持一致。我们首先在格子点上生成颗粒的位置信息，同时将随机缩放系数考虑进来。

import numpy as np
import sys, random
gui = True
sim = None
randSeed = 12345654 #to keep the same config.
random.seed(randSeed)
from dem.core import *
from dem.rtdem import *
from pySudoMath import *
if gui:
    app.core.setAnalysisType(AnalysisType="RTDEM", randSeed = randSeed)
    sim=app.core.sim
else:
    sim = DEMSim()

#define a lattice grid
#R: distance between two neighboring nodes
#num_x: number of nodes along x axis
#num_y: number of nodes along y axis
#num_z: number of nodes along z axis
#return a list of the postions of all nodes
scales = list()
def GridInitial(R,num_x=10,num_y=10,num_z=20, shift=[0,0,0]):#this part is slow, but just for test
    pos = list()
    for k in range(num_z):
        for j in range(num_y):
            for i in range(num_x):
                x = i*R*2.0*1.2+R+shift[0]+random.uniform(0, 0.1*R)
                y = j*R*2.0*1.2+R+shift[1]+random.uniform(0, 0.1*R)
                z = k*R*2.0*1.2+R+shift[2]
                pos.append(Vector3f(x,y,z))
                # 缩放系数
                scales.append(random.uniform(0.8,1.6))
    return pos

psize = 0.09
Num = 5
Num_z = 20
pos = GridInitial(psize,num_x=Num,num_y=Num,num_z=Num_z,shift = [0.*psize,1.0*psize,3.0*psize])
pnum = len(pos)
ori = list()
for i in range(pnum):
    ang = random.uniform(0,np.pi)
    vec = Vector3f(random.uniform(0,1),random.uniform(0,1),random.uniform(0,1))
    #ori.append(Quaternionr(-ang/2, vec))
    ori.append(Quaternionr(-3.1415926/4, Vector3f(1.0, 0, 0)))

7.5.2. 生成颗粒和容器

• 生成颗粒，并施加缩放系数

poly=PolyhedronData()
poly.setPosOri( pos,  ori)
poly.loadSTL("./sand.stl", 0.001)
poly.computGeometry()
span = poly.bounds.span()
print(span)
# 添加缩放系数
poly.setScaleFactors(np.array( scales ))
sim.pdata.addObject(poly)

• 生成容器

box=PolyhedronData()
box.loadSTL("./box.stl", Vector3f(0.6,0.6,0.6), False)
box.setPosition( [Vector3f(0.5,0.5,1.8)])
box.setMovable(False)
sim.pdata.addObject(box)

7.5.3. 其它模型设置

与上一个例子类似。

# 颗粒材料
mat = Material()
mat.density = 2650.0
mat.kn = 1e4*1e2
mat.ks = 1e4
mat.friction = 0.3
sim.pdata.material = mat
# 容器材料
wmat = Material()
wmat.density = 1000.0
wmat.kn = 1e5*1e3
wmat.ks = 1e5
wmat.friction = 0.3
sim.pdata.wallMaterial = wmat

sim.integrator.gravity = Vector3f(0,0,-10.0)
sim.integrator.damping = 0.3
sim.integrator.viscousDamping = 0.01

sim.init()

sim.dt = 1e-4