编辑代码

SUBROUTINE UMAT(STRESS, STATEV, DDSDDE, SSE, SPD, SCD, RPL, DDSDDT,
1 DRPLDE, DRPLDT, STRAN, DSTRAN, TIME, DTIME, TEMP, DTEMP, PREDEF,
2 DPRED, CMNAME, NDI, NSHR, NTENS, NSTATV, PROPS, NPROPS, COORDS,
3 DROT, PNEWDT, CELENT, DFGRD0, DFGRD1, NOEL, NPT, LAYER, KSPT,
4 KSTEP, KINC)

    IMPLICIT NONE

    ! 定义变量
    REAL*8 STRESS(NTENS), STATEV(NSTATV), DDSDDE(NTENS, NTENS)
    REAL*8 STRAN(NTENS), DSTRAN(NTENS), TEMP, DTEMP
    REAL*8 PROPS(NPROPS), TIME, DTIME
    INTEGER NDI, NSHR, NTENS, NSTATV, NPROPS

    ! 材料参数
    REAL*8 E_A, E_M, nu, sigma_cr_AM, sigma_cr_MA, M_f, A_s, epsilon_L
    REAL*8 xi, xi_T, xi_S, D(6,6)

    ! 初始化
    E_A = PROPS(1)  ! 奥氏体弹性模量
    E_M = PROPS(2)  ! 马氏体弹性模量
    nu = PROPS(3)   ! 泊松比
    sigma_cr_AM = PROPS(4)  ! A→M临界应力
    sigma_cr_MA = PROPS(5)  ! M→A临界应力
    M_f = PROPS(6)  ! 马氏体相变结束温度
    A_s = PROPS(7)  ! 奥氏体相变开始温度
    epsilon_L = PROPS(8)  ! 最大相变应变

    xi = STATEV(1)  ! 马氏体体积分数
    xi_T = STATEV(2)  ! 温度诱导马氏体
    xi_S = STATEV(3)  ! 应力诱导马氏体

    ! 计算弹性模量张量
    CALL CALC_D(D, E_A, E_M, nu, xi)

    ! 更新应力
    STRESS = STRESS + MATMUL(D, DSTRAN)

    ! 更新相变条件
    CALL UPDATE_PHASE_TRANSFORMATION(xi, xi_T, xi_S, TEMP, STRESS, sigma_cr_AM, sigma_cr_MA, M_f, A_s)

    ! 更新状态变量
    STATEV(1) = xi
    STATEV(2) = xi_T
    STATEV(3) = xi_S

    ! 更新雅可比矩阵
    DDSDDE = D

    RETURN
END SUBROUTINE UMAT

SUBROUTINE CALC_D(D, E_A, E_M, nu, xi)
    ! 计算弹性模量张量
    IMPLICIT NONE
    REAL*8 D(6,6), E_A, E_M, nu, xi
    REAL*8 E, G, K
    INTEGER i, j

    E = E_A * (1 - xi) + E_M * xi
    G = E / (2 * (1 + nu))
    K = E / (3 * (1 - 2 * nu))

    D = 0.0
    D(1:3, 1:3) = K + 4 * G / 3
    D(4, 4) = G
    D(5, 5) = G
    D(6, 6) = G

    RETURN
END SUBROUTINE CALC_D

SUBROUTINE UPDATE_PHASE_TRANSFORMATION(xi, xi_T, xi_S, TEMP, STRESS, sigma_cr_AM, sigma_cr_MA, M_f, A_s)
    ! 更新相变条件
    IMPLICIT NONE
    REAL*8 xi, xi_T, xi_S, TEMP, STRESS(6), sigma_cr_AM, sigma_cr_MA, M_f, A_s
    REAL*8 sigma_eq

    ! 计算等效应力
    sigma_eq = SQRT(STRESS(1)**2 + STRESS(2)**2 + STRESS(3)**2)

    ! 奥氏体到马氏体相变
    IF (sigma_eq >= sigma_cr_AM .AND. TEMP <= M_f) THEN
        xi = xi + 0.1  ! 假设相变速率为0.1
    END IF

    ! 马氏体到奥氏体相变
    IF (sigma_eq <= sigma_cr_MA .AND. TEMP >= A_s) THEN
        xi = xi - 0.1  ! 假设相变速率为0.1
    END IF

    ! 限制马氏体体积分数在0到1之间
    xi = MAX(0.0, MIN(1.0, xi))

    RETURN
END SUBROUTINE UPDATE_PHASE_TRANSFORMATION