压力容器#

本例演示如何创建一个基本压力容器并对其施加压力。

Also shown here:

从 MAPDL 获取应力结果的各种方法。
PRNSOL、VGET（更高效的封装）和传统读取器之间的比较。
使用 PRNSOL 时有关 FULL 图形与 POWER 图形的注意事项。

import numpy as np

from ansys.mapdl.core import launch_mapdl

# start mapdl, enter the preprocessor, and set the units
mapdl = launch_mapdl()

mapdl.clear()
mapdl.prep7()

# US Customary system using inches (in, lbf*s2/in, s, °F).  美国惯用制英寸（英寸，磅英尺*平方英寸，秒，°F）。
mapdl.units("BIN")

C:\Users\ff\AppData\Local\Programs\Python\Python310\lib\site-packages\ansys\tools\path\path.py:818: DeprecationWarning: This method is going to be deprecated in future versions. Please use 'get_mapdl_path'.
  warnings.warn(

U.S. CUSTOMARY INCH UNITS SPECIFIED FOR INTERNAL
  LENGTH      = INCHES (IN)
  MASS        = LBF-S**2/IN
  TIME        = SECONDS (SEC)
  TEMPERATURE = FAHRENHEIT
  TOFFSET     = 460.0
  FORCE       = LBF
  HEAT        = IN-LBF
  PRESSURE    = PSI (LBF/IN**2)
  ENERGY      = IN-LBF
  POWER       = IN-LBF/SEC

 INPUT  UNITS ARE ALSO SET TO BIN

设置材料和单元类型

mapdl.et(1, "SOLID285")
mapdl.mp("EX", 1, 10e6)
mapdl.mp("PRXY", 1, 0.3)
mapdl.mp("DENS", 1, 0.1)
print(mapdl.mplist())

LIST MATERIALS        1 TO        1 BY        1
  PROPERTY= ALL

 MATERIAL NUMBER        1

      TEMP        EX
               0.1000000E+08

      TEMP        DENS
               0.1000000

      TEMP        PRXY
               0.3000000

创建几何图形

# area generation
height = 10
inner_width = 2.5
outer_width = 3.5
mapdl.rectng(inner_width, outer_width, 0, height)
mapdl.cyl4(0, height, inner_width, 0, outer_width, 90)

# combine areas
a_comb = mapdl.aadd(1, 2)
mapdl.aplot(color="grey", background="w", show_area_numbering=True)

# Generate a cylindrical volume by rotating an area pattern about an axis
mapdl.vrotat(a_comb, pax1=6, arc=90)
mapdl.vplot(background="w",show_volume_numbering=True)

创建网格

mapdl.smrtsize(1)
mapdl.esize(0.25, 0)
mapdl.mshape(1, "3D")
mapdl.mshkey(0)
mapdl.vmesh("ALL")
mapdl.eplot(color="grey", background="w")

Solve

# 边界条件选择
mapdl.geometry.area_select([3, 5, 7])
mapdl.da("ALL", "SYMM")
mapdl.allsel()

# 施加压力
mapdl.geometry.area_select([1, 6])
mapdl.sfa("ALL", 1, "PRES", 1000)
mapdl.allsel()

# solver
mapdl.run("/SOL")
mapdl.antype(0)
mapdl.outres("ALL", "ALL")
mapdl.run("/STATUS,SOLU")
sol_output = mapdl.solve()
mapdl.finish()

FINISH SOLUTION PROCESSING

 ***** ROUTINE COMPLETED *****  CP =         1.875

Post-Processing#

输入 MAPDL 后处理命令 (/POST1) 并获取单一静态解的冯米斯应力。在这里，我们直接使用 MAPDL 来获取结果，使用 VGET 方法的包装器来高效的获取结果，而无需输出到磁盘。

# 进入后处理程序
mapdl.post1()
mapdl.set(1, 1)

# 直接来自 MAPDL 的 VGET 命令的结果
# VGET, __VAR__, NODE, , S, EQV
nnum = mapdl.mesh.nnum # Array of node numbers.
von_mises_mapdl = mapdl.post_processing.nodal_eqv_stress()

# 我们可以用以下方法打印出每个节点的解：

print(f"\nNode  Stress (psi)")
for node_num, stress_value in zip(nnum[:5], von_mises_mapdl[:5]):
    print(f"{node_num:<5d} {stress_value:.3f}")
print("...")

# 或直接获取最大应力值和相应的节点
idx = np.argmax(von_mises_mapdl)
node_num = nnum[idx]
stress_value = von_mises_mapdl[idx]
print(f"\nMaximum Stress")
print(f"Node  Stress (psi)")
print(f"{node_num:<5d} {stress_value:.3f}")

Node  Stress (psi)
1     3305.107
2     1895.056
3     1398.011
4     1372.698
5     867.279
...

Maximum Stress
Node  Stress (psi)
1000  3477.022

Plot the results

mapdl.post_processing.plot_nodal_eqv_stress(cpos="zy")

我们也可以使用传统文件阅读器 ansys-mapdl-reader 直接访问结果文件，得到完全相同的结果。

# 访问结果
result = mapdl.result

# 获取冯米塞斯应力，并证明它等同于从 MAPDL 中获取的应力。
nnum, stress = result.principal_nodal_stress(0)
von_mises = stress[:, -1]  # von-Mises 应力是最右边的一列
min_von_mises, max_von_mises = np.min(von_mises), np.max(von_mises)
print("All close:", np.allclose(von_mises, von_mises_mapdl))

All close: True

这些结果等同于 PRNSOL 的结果。

Note

使用 mapdl.graphics('POWER') 启用 POWER GRAPHICS 将改变平均后的结果。

mapdl.header("OFF", "OFF", "OFF", "OFF", "OFF", "OFF")
table = mapdl.prnsol("S", "PRIN").splitlines()[1:]
prnsol_eqv = np.genfromtxt(table)[:, -1]  # eqv 是最后一列

# 显示这些数据是相等的（由于 PRNSOL 内的四舍五入，因此为 RTOL）
print("All close:", np.allclose(von_mises, prnsol_eqv, rtol=1e-4))

print(f"LEGACY Reader and MAPDL VGET Min: {min_von_mises}")
print(f"PRNSOL MAPDL Min:                 {prnsol_eqv.min()}")
print()
print(f"LEGACY Reader and MAPDL VGET Max: {max_von_mises}")
print(f"PRNSOL MAPDL Max:                 {prnsol_eqv.max()}")

All close: True
LEGACY Reader and MAPDL VGET Min: 716.7400209196994
PRNSOL MAPDL Min:                 716.74

LEGACY Reader and MAPDL VGET Max: 3477.0215611712856
PRNSOL MAPDL Max:                 3477.0

Stop mapdl#

mapdl.exit()

Total running time of the script: (0 minutes 8.876 seconds)