Examples

Below are some examples of how to use the library. To compile the examples into an object file (.obj) that can be used by Abaqus, you can run the following command:

abqcy compile <path-to-your-subroutine>

Example: Elastic umat subroutine

This example shows how to write an Abaqus elastic umat subroutine in Cython.

 1cdef extern from "<aba_for_c.h>":
 2    pass
 3
 4
 5cdef extern void umat(
 6    double *stress, double *statev, double *ddsdde, double *sse, double *spd,
 7    double *scd, double *rpl, double *ddsddt, double *drplde, double *drpldt,
 8    double *stran, double *dstran, double *time, double *dtime, double *temp,
 9    double *dtemp, double *predef, double *dpred, char *cmname, int *ndi,
10    int *nshr, int *ntens, int *nstatv, double *props, int *nprops, double *coords,
11    double *drot, double *pnewdt, double *celent, double *dfgrd0, double *dfgrd1,
12    int *noel, int *npt, int *layer, int *kspt, int *jstep, int *kinc,
13):
14    cdef double E, nu, lam, G
15    E, nu = props[0], props[1]
16    lam = E * nu / ((1.0 + nu) * (1.0 - 2.0 * nu))
17    G = E / (2.0 * (1.0 + nu))
18
19    cdef int i, j
20    for i in range(3):
21        for j in range(3):
22            ddsdde[6 * i + j] = lam
23        ddsdde[6 * i + i] += 2.0 * G
24        ddsdde[6 * (i + 3) + (i + 3)] = G
25    for i in range(6):
26        for j in range(6):
27            stress[i] += ddsdde[6 * i + j] * dstran[j]

 1import cython
 2
 3
 4def umat(
 5    stress, statev, ddsdde, sse, spd, scd, rpl, ddsddt, drplde, drpldt, stran, dstran,
 6    time, dtime, temp, dtemp, predef, dpred, cmname, ndi, nshr, ntens, nstatv, props,
 7    nprops, coords, drot, pnewdt, celent, dfgrd0, dfgrd1, noel, npt, layer, kspt,
 8    jstep, kinc,
 9):  # fmt: skip
10    cython.declare(E=cython.double, nu=cython.double, lam=cython.double, G=cython.double)
11    E, nu = props[0], props[1]
12    lam = E * nu / ((1.0 + nu) * (1.0 - 2.0 * nu))
13    G = E / (2.0 * (1.0 + nu))
14
15    cython.declare(i=cython.int, j=cython.int)
16    for i in range(3):
17        for j in range(3):
18            ddsdde[6 * i + j] = lam
19        ddsdde[6 * i + i] += 2.0 * G
20        ddsdde[6 * (i + 3) + (i + 3)] = G
21    for i in range(6):
22        for j in range(6):
23            stress[i] += ddsdde[6 * i + j] * dstran[j]

Note

You will need to add the Cython header file (.pxd) along with the Python file (.py) in order to use the Cython declarations.

 1cdef extern from "<aba_for_c.h>":
 2    pass
 3
 4
 5cdef extern void umat(
 6    double *stress, double *statev, double *ddsdde, double *sse, double *spd,
 7    double *scd, double *rpl, double *ddsddt, double *drplde, double *drpldt,
 8    double *stran, double *dstran, double *time, double *dtime, double *temp,
 9    double *dtemp, double *predef, double *dpred, char *cmname, int *ndi,
10    int *nshr, int *ntens, int *nstatv, double *props, int *nprops, double *coords,
11    double *drot, double *pnewdt, double *celent, double *dfgrd0, double *dfgrd1,
12    int *noel, int *npt, int *layer, int *kspt, int *jstep, int *kinc,
13)