以下是使用Python編寫粘塑性UMAT子程序的簡單示例代碼：

```python
# Importing Required Modules
from abaqus import *
from abaqusConstants import *
from odbAccess import *
from numpy import *
from math import *

# Defining Input Variables
def UMAT(stress, statev, ddsdde, rpl, ddsddt, drplde, drpldt, stran, dstran, time, dtime, temp, dtemp, predef, dpred, cmname, ndi, nshr, ntens, nstatv, props, nprops, coords, drot, pnewdt, celent, dfgrd0, dfgrd1, noel, npt, layer, kspt, kstep, kinc):

 ?# Defining Material Properties
 ?E0 = props[0]
 ?nu = props[1]
 ?G0 = E0 / (2.0 * (1.0 + nu))
 ?Einf = props[2]
 ?eta = props[3]
 ?n = props[4]
 ?alpha = props[5]
 ?beta = props[6]
 ?gamma = props[7]
 ?T = temp

 ?# Calculate Deformation Gradient
 ?F = dot(dfgrd1.T, dfgrd0)

 ?# Calculate Strain Tensor
 ?strain = 0.5 * (dot(F.T, F) - identity(3))

 ?# Calculate Stress Tensor
 ?E = 0.5 * (strain + strain.T)
 ?S = 2 * G0 * (E - alpha * T * identity(3)) + (Einf - G0 * exp(-eta * T**n)) * identity(3) + beta * stress
 ?stress = dot(S, strain)

 ?# Update State Variables
 ?statev_new = [0]*len(statev)
 ?for i in range(len(statev)):
 ? ? ?statev_new[i] = statev[i]

 ?# Compute Material Tangent Stiffness
 ?stifftan = [0.0]*(ntens*(ntens+1)/2)
 ?return(stress, statev_new, stifftan)
```

這是一個簡單的UMAT，僅實現(xiàn)了材料響應和計算應力，它可以輕松修改和擴展，以包含更多材料特性和模擬選項。注意，此代碼并未經(jīng)過驗證測試，只作為示例演示UMAT子程序的編寫方法。