Product: ABAQUS/Standard
Elasticity
Young's modulus, E = 20.0E6
Poisson's ratio, 
= 0.3
Creep
LAW=TIME/STRAIN
A = 2.5E–27
n = 5.0
m = –0.2
LAW=HYPERB
A = 2.5E–27
B = 4.4E–4
n = 5.0
= 0.0
R = 8.314
(The units are not important.)
The tests in this section are set up as cases of homogeneous deformation of a single element. Consequently, the results are identical for all integration points within the element. The elements have unit dimensions except in the loading direction in which they have a length of 10. The constitutive path is integrated with the *VISCO procedure using automatic incrementation. Therefore, the number of increments varies from test to test. The results are reported at a convenient increment near the halfway point of the response and at the end of the test.
LAW=TIME, uniaxial tension creep, C3D8 elements.
LAW=STRAIN, uniaxial tension creep, C3D8 elements.
LAW=HYPERB, uniaxial tension creep, C3D8 elements.
LAW=TIME, uniaxial tension relaxation, C3D8 elements.
LAW=STRAIN, uniaxial tension relaxation, C3D8 elements.
LAW=TIME, uniaxial tension creep, linear perturbation with *LOAD CASE, CPS4 elements.
LAW=STRAIN, uniaxial tension creep, CPS4 elements.
LAW=TIME, uniaxial tension relaxation, CPS4 elements.
LAW=STRAIN, uniaxial tension relaxation, CPS4 elements.
LAW=TIME, uniaxial tension creep, T3D2 elements.
LAW=STRAIN, uniaxial tension creep, T3D2 elements.
LAW=TIME, uniaxial tension relaxation, T3D2 elements.
LAW=STRAIN, uniaxial tension relaxation, T3D2 elements.
Linear perturbation with *LOAD CASE, LAW=TIME, uniaxial tension creep, C3D8 elements.
Elasticity
Young's modulus, E = 20.0E6
Poisson's ratio, = 0.3
Creep
A = 2.5E–27
n = 5.0
m = –0.2
Anisotropic creep ratios: 1.5, 1.2, 1.0, 1.0, 1.0, 1.0
(The units are not important.)
The constitutive path is integrated with the *VISCO procedure using automatic incrementation. Therefore, the number of increments varies from test to test.
LAW=TIME, uniaxial tension creep in direction 1, C3D8 elements.
LAW=TIME, uniaxial tension creep in direction 2, C3D8 elements.
LAW=TIME, uniaxial tension creep in direction 3, C3D8 elements.
LAW=STRAIN, uniaxial tension creep in direction 1, C3D8 elements.
LAW=STRAIN, uniaxial tension creep in direction 2, C3D8 elements.
LAW=STRAIN, uniaxial tension creep in direction 3, C3D8 elements.
Linear perturbation with *LOAD CASE, LAW=TIME, uniaxial tension creep in direction 1, C3D8 elements.
Elasticity
Young's modulus, E = 20.0E6
Poisson's ratio, = 0.3
Creep
A = 1.0E–24
n = 5.0
m = –0.2
Swelling
Volumetric swelling rate = 2.0E–6
(The units are not important.)
The tests in this section verify the coupled Mises creep and plasticity model for problems involving uniaxial tension, shear, bending, and torsion. The test cases consider stress spaces with 1, 2, or 3 direct components. Both time and strain creep laws, as well as volumetric swelling, are considered with the constitutive path integrated by the *VISCO procedure using automatic incrementation. Explicit and implicit time integration are employed, with automatic switching to the implicit scheme once a material point goes plastic. The solution's accuracy is verified by comparing it to test cases employing extremely fine time integration.
LAW=TIME, uniaxial tension creep, T3D2 elements.
LAW=TIME, uniaxial tension creep, CPS4 elements.
LAW=TIME, uniaxial compression creep, Linear perturbation with *LOAD CASE, S4R elements.
LAW=TIME, uniaxial compression creep, S4 elements.
LAW=TIME, uniaxial tension creep, C3D8R elements.
LAW=STRAIN, uniaxial tension creep, C3D8R elements.
LAW=STRAIN, uniaxial tension creep, Hardening=Kinematic, C3D8R elements.
LAW=STRAIN, shear creep, CPS4 elements.
LAW=STRAIN, shear creep, C3D8 elements.
Volumetric swelling, T3D2 elements.
Volumetric swelling, CPS4 elements.
Volumetric swelling, C3D8 elements.
LAW=TIME, creep law, combined torsion and bending, B32 elements.
Elasticity
Young's modulus, E = 300.0E3
Poisson's ratio, = 0.3
Plasticity
Creep
For the time and strain creep laws:
A = 0.5E–7
n = 1.1
m = –0.2
The Singh-Mitchell creep law parameters are varied. For example:
A = 0.002
= 1.0E–6
m = –1.0
= 1.0
(The units are not important.)
The tests in this section verify the coupled Drucker-Prager creep and plasticity model. The tests are set up as cases of homogeneous deformation of a single solid element of unit dimension subjected to uniaxial tension and compression, shear, and hydrostatic tension. The Singh-Mitchell, time, and strain hardening creep laws are considered with the constitutive path integrated by the *VISCO procedure. Explicit and implicit time integration are employed, with automatic switching to the implicit scheme once a material point goes plastic.
LAW=SINGHM, uniaxial compression, C3D8 elements.
LAW=SINGHM, uniaxial tension, C3D8 elements.
LAW=SINGHM, shear, C3D8R elements.
LAW=SINGHM, hydrostatic tension, C3D8R elements.
LAW=SINGHM, uniaxial compression with temperature dependence, C3D8 elements.
LAW=TIME, uniaxial tension, C3D8 elements.
LAW=STRAIN, uniaxial tension, perturbation step with *LOAD CASE, C3D8 elements.
LAW=USER, uniaxial tension, C3D8 elements.
User subroutine CREEP used in mdcuco3hut.inp.
Elasticity
Young's modulus, E = 300.0E4
Poisson's ratio, = 0.3
Cap plasticity
Creep (for both cohesion and consolidation)
For LAW=TIME:
A = 1.0E–24
n = 5
m = 0.0
For LAW=STRAIN:
A = 7.0E–26
n = 5
m = 0.0
For LAW=SINGHM:
A = 0.002
= 1.6E–4
m = 0.0
= 1.0
For LAW=USER:
A user subroutine for the time creep law specified earlier is implemented.
(The units are not important.)
The tests in this section verify the cap creep and plasticity model. The tests are set up as cases of homogeneous deformation of a single solid element of unit dimension. To validate the model, the element is subjected to various stress paths including uniaxial tension and compression, shear, hydrostatic tension and compression, and triaxial compression. The Singh-Mitchell creep law, the time and strain hardening creep laws, and a user-defined creep model are considered with the constitutive path integrated by the *VISCO procedure. Explicit and implicit time integration are employed, with automatic switching to the implicit scheme once a material point goes plastic.
LAW=SINGHM, hydrostatic compression, C3D8R elements.
LAW=SINGHM, uniaxial compression, C3D8 elements.
LAW=STRAIN, uniaxial tension, C3D8 elements.
LAW=STRAIN, shear, C3D8R elements.
LAW=TIME, hydrostatic tension, C3D8R elements.
LAW=TIME, triaxial compression, C3D8R elements.
LAW=USER, triaxial compression, C3D8R elements.
User subroutine CREEP used in mccuco3ctc.inp.
Additional verification problems were obtained by adding creep to the plasticity model of “Limit load calculations with granular materials,” Section 1.14.4 of the ABAQUS Benchmarks Manual, and “Finite deformation of an elastic-plastic granular material,” Section 1.14.5 of the ABAQUS Benchmarks Manual. For these cases a small creep strain rate was selected to verify the plasticity component of the coupled creep and plasticity models. Thus, the results should be comparable to the equivalent problem without creep, although they are separate ABAQUS material models. These verification problems test both the Drucker-Prager creep and the Drucker-Prager/Cap creep models.
Further verification problems for Mises creep and plasticity were obtained by adding plasticity to the problems described in “Creep of a thick cylinder under internal pressure,” Section 3.2.15 of the ABAQUS Benchmarks Manual, and “Ct-integral evaluation,” Section 1.15.6 of the ABAQUS Benchmarks Manual. For the example described in “Creep of a thick cylinder under internal pressure,” Section 3.2.15 of the ABAQUS Benchmarks Manual, the initial application of the pressure plastifies the cylinder during the first step of the analysis; and the creep response is then developed in the second step. For the example described in “Ct-integral evaluation,” Section 1.15.6 of the ABAQUS Benchmarks Manual, the plastic deformation is very small and localized. Plastification occurs only during the preloading *STATIC step. As a result, the 
-integrals calculated by ABAQUS in the early stages of the *VISCO step are expected to differ somewhat from the ones calculated in the creep-only case and are not path independent. Later on, when larger scale creep dominates the stress fields, the -integrals calculated should converge toward the same values as obtained in the creep-only case and become path independent.
The results obtained show good agreement with the corresponding example problems. The addition of creep in the first two problems has little effect on the plastic results, and the addition of plasticity in the second two problems has little effect on the creep results.
Verification input file for the problem described in “Limit load calculations with granular materials,” Section 1.14.4 of the ABAQUS Benchmarks Manual.
Verification input file for the problem described in “Limit load calculations with granular materials,” Section 1.14.4 of the ABAQUS Benchmarks Manual.
Verification input file for the problem described in “Finite deformation of an elastic-plastic granular material,” Section 1.14.5 of the ABAQUS Benchmarks Manual.
Verification input file for the problem described in “Creep of a thick cylinder under internal pressure,” Section 3.2.15 of the ABAQUS Benchmarks Manual.
Verification input file for the problem described in “Ct-integral evaluation,” Section 1.15.6 of the ABAQUS Benchmarks Manual.
= 40.0
= 40.0
= 0.5