# 弹塑性材料VUMAT子程序代码示例 以下是一个简化的弹塑性材料VUMAT子程序代码框架，适用于ABAQUS显式分析。这个示例实现了各向同性硬化弹塑性模型。 ```fortran SUBROUTINE VUMAT( * NBLOCK, NDIR, NSHR, NSTATEV, NFIELDV, NPROPS, LANNEAL, * STEPTIME, TOTALTIME, DT, CMNAME, COORDMP, CHARLENGTH, * PROPS, DENSITY, STRAININC, RELSPININC, * TEMPOLD, STRETCHOLD, DEFGRADOLD, FIELDOLD, * STRESSOLD, STATEOLD, ENERINTERNOLD, ENERINELASOLD, * TEMPNEW, STRETCHNEW, DEFGRADNEW, FIELDNEW, * STRESSNEW, STATENEW, ENERINTERNNEW, ENERINELASNEW) INCLUDE 'VABA_PARAM.INC' DIMENSION PROPS(NPROPS), DENSITY(NBLOCK), COORDMP(NBLOCK,*), * CHARLENGTH(NBLOCK), STRAININC(NBLOCK,NDIR+NSHR), * RELSPININC(NBLOCK,NSHR), TEMPOLD(NBLOCK), * STRETCHOLD(NBLOCK,NDIR+NSHR), * DEFGRADOLD(NBLOCK,NDIR+NSHR+NSHR), * FIELDOLD(NBLOCK,NFIELDV), STRESSOLD(NBLOCK,NDIR+NSHR), * STATEOLD(NBLOCK,NSTATEV), ENERINTERNOLD(NBLOCK), * ENERINELASOLD(NBLOCK), TEMPNEW(NBLOCK), * STRETCHNEW(NBLOCK,NDIR+NSHR), * DEFGRADNEW(NBLOCK,NDIR+NSHR+NSHR), * FIELDNEW(NBLOCK,NFIELDV), * STRESSNEW(NBLOCK,NDIR+NSHR), STATENEW(NBLOCK,NSTATEV), * ENERINTERNNEW(NBLOCK), ENERINELASNEW(NBLOCK) CHARACTER*80 CMNAME PARAMETER (ZERO=0.D0, ONE=1.D0, TWO=2.D0, THREE=3.D0, HALF=0.5D0, * THIRD=1.D0/3.D0, TWOTHIRDS=2.D0/3.D0, * SQRT3=1.7320508075688772935274463415059D0) ! 材料参数 REAL*8 YOUNG, POISSON, YIELD, HARD REAL*8 E, NU, SYIELD, H ! 弹性矩阵 REAL*8 D(6,6) ! 从PROPS中读取材料参数 YOUNG = PROPS(1) ! 杨氏模量 POISSON = PROPS(2) ! 泊松比 YIELD = PROPS(3) ! 初始屈服应力 HARD = PROPS(4) ! 硬化模量 ! 计算弹性矩阵 E = YOUNG NU = POISSON CALL ELASTIC_MATRIX(E, NU, D) ! 对每个材料点循环 DO KM = 1, NBLOCK ! 获取应变增量 DEPS(1) = STRAININC(KM,1) DEPS(2) = STRAININC(KM,2) DEPS(3) = STRAININC(KM,3) DEPS(4) = STRAININC(KM,4) DEPS(5) = STRAININC(KM,5) DEPS(6) = STRAININC(KM,6) ! 获取旧应力 STRESS(1) = STRESSOLD(KM,1) STRESS(2) = STRESSOLD(KM,2) STRESS(3) = STRESSOLD(KM,3) STRESS(4) = STRESSOLD(KM,4) STRESS(5) = STRESSOLD(KM,5) STRESS(6) = STRESSOLD(KM,6) ! 获取等效塑性应变(状态变量) EQPLAS = STATEOLD(KM,1) ! 弹性预测步 CALL MATMUL(D, DEPS, DSIGMA, 6, 6, 1) STRESS_TRIAL(1:6) = STRESS(1:6) + DSIGMA(1:6) ! 计算偏应力和静水压力 CALL DEVIATORIC_STRESS(STRESS_TRIAL, SDEV, PRESSURE) ! 计算等效应力 VM_STRESS = SQRT(1.5D0 * (SDEV(1)2 + SDEV(2)2 + SDEV(3)2 + * TWO*(SDEV(4)2 + SDEV(5)2 + SDEV(6)2))) ! 计算当前屈服应力 YIELD_CURRENT = YIELD + HARD * EQPLAS ! 检查屈服条件 F = VM_STRESS - YIELD_CURRENT IF (F .LE. ZERO) THEN ! 弹性步 STRESSNEW(KM,1:6) = STRESS_TRIAL(1:6) STATENEW(KM,1) = EQPLAS ELSE ! 塑性步 ! 计算流动方向 N(1:6) = (1.5D0/VM_STRESS) * SDEV(1:6) ! 计算塑性乘子 DLAMBDA = F / (THREE*G + HARD) ! 更新应力 STRESSNEW(KM,1:6) = STRESS_TRIAL(1:6) - TWO*G*DLAMBDA*N(1:6) ! 更新等效塑性应变 DEQPLAS = SQRT(TWOTHIRDS) * DLAMBDA STATENEW(KM,1) = EQPLAS + DEQPLAS END IF ! 更新内能 ENERINTERNNEW(KM) = ENERINTERNOLD(KM) + * HALF * DOT_PRODUCT(STRESSOLD(KM,1:6)+STRESSNEW(KM,1:6), * STRAININC(KM,1:6)) END DO RETURN END SUBROUTINE ELASTIC_MATRIX(E, NU, D) IMPLICIT NONE REAL*8 E, NU, D(6,6) REAL*8 C1, C2 C1 = E / (1.D0 + NU) / (1.D0 - 2.D0*NU) C2 = NU / (1.D0 - NU) D = 0.D0 D(1,1) = C1 * (1.D0 - NU) D(2,2) = D(1,1) D(3,3) = D(1,1) D(1,2) = C1 * NU D(1,3) = D(1,2) D(2,1) = D(1,2) D(2,3) = D(1,2) D(3,1) = D(1,2) D(3,2) = D(1,2) D(4,4) = C1 * (1.D0 - 2.D0*NU) / 2.D0 D(5,5) = D(4,4) D(6,6) = D(4,4) RETURN END SUBROUTINE DEVIATORIC_STRESS(STRESS, SDEV, PRESSURE) IMPLICIT NONE REAL*8 STRESS(6), SDEV(6), PRESSURE PRESSURE = -(STRESS(1) + STRESS(2) + STRESS(3)) / 3.D0 SDEV(1) = STRESS(1) + PRESSURE SDEV(2) = STRESS(2) + PRESSURE SDEV(3) = STRESS(3) + PRESSURE SDEV(4) = STRESS(4) SDEV(5) = STRESS(5) SDEV(6) = STRESS(6) RETURN END ``` ## 代码说明 1. 这个VUMAT实现了各向同性硬化的弹塑性材料模型，采用Mises屈服准则。 2. 需要4个材料参数：杨氏模量、泊松比、初始屈服应力和硬化模量。 3. 使用了一个状态变量存储等效塑性应变。 4. 采用弹性预测-塑性修正的径向返回算法。 ## 使用注意事项 1. 在实际应用中需要添加更多的错误检查和边界条件处理。 2. 对于大变形问题，可能需要考虑客观应力率。 3. 硬化模型可以扩展为更复杂的非线性硬化或随动硬化模型。 ## 三条额外需要注意的逻辑点 1. 确保材料参数PROPS数组的顺序与代码中读取的顺序一致。 2. 状态变量STATENEW需要在每个增量步正确更新。 3. 对于大应变问题，需要考虑变形梯度的更新和应力的客观性。 [2025-05-20 19:07:40 | AI写代码神器 | 2184点数解答]