The library contains routines for implicit and
explicit integration of elastic, plastic and
ductile damage material models, via Abaqus
user material subroutines. It can be used
together with
CASUP
(Cellular Automata library for SUPercomputers),
to understand and quantify damage and fracture on
the micro-scale.
The
cafe.old
directory is an implementation of CAFE idea fully within an Abaqus VUMAT subroutine.
ABUMPACK is distributed under 2 clause BSD style license.
See
LICENSE
file.
With any questions, bug reports, feedback and any other comments please submit a ticket.
26-DEC-2017: release 4. GTN VUMAT routines have been updated. Some disagreement with Abaqus own GTN is observed. This is expected where "finite rotation of a material point is accompanied by finite shear". This is because VUMAT uses the Green-Naghdi stress rate, whereas Abaqus own solver uses the Jaumann stress rate. See the VUMAT manual for full details.
JAN-2017 | NOV-2016 | JUL-2016 | MAR-2016
SEM images of ductile fracture surfaces of a thermomechanically controlled rolled (TMCR) steel, at different magnifications.
Below are the results of linking the single FE shear+tension model (see below) with CASUP. The results show the evolution of the maximum principal stress, σ1, resolved to 3 crystallographic planes: 100, 110, 111. In all cases, the preferential plane is chosen of all planes of the same family.
The two plots are the outcomes of 2 runs, with 2 randomly chosen orientations of some cubic single crystal enclosed in the finite element. These show (a) a complex evolution of the resolved stresses during the deformation, and (b) significant variation in stresses with the orientation of the crystal. This illustrates some of the capabilities of a cellular automata finite element (CAFE) model.
We use Levenberg-Marquardt (LM)
dnls1.f
and Powell's dogleg (DL)
dnsq.f
solution routines from
Slatec
library.
For GTN model the LM method shows
faster convergence than the DL.
For more details see:
A. Shterenlikht, N. A. Alexander,
Levenberg-Marquardt vs Powell's dogleg method for Gurson-Tvergaard-Needleman plasticity model
Computer Methods in Applied Mechanics and Engineering 237-240:1-9, 2012,
DOI:
10.1016/j.cma.2012.04.018,
PDF with final corrections.
This is an 3-point impact bend test of a notched bar. The standard bar dimentions are 50 mm length and 10 mm by 100 mm cross section. The striker geometry is according to British Standard BS EN ISO 148-3:2016. GTN VUMAT - explicit dynamic analysis. Levenberg-Marquardt solver is used. The contour plots show von Mises stress.
Animation, 7MB, avi.
A circular cylinder bar is loaded in shear under displacement control. GTN UMAT material model is used with the Levenberg-Marquardt non-linear solver. The contour plot shows von Mises stress.
Animation, 9M avi.
A 3D model of a circular cylinder under axial tension. Displacement control is used. GTN UMAT material model is used with the Levenberg-Marquardt non-linear solver. The contour plot shows the volumetric void fraction (VVF) variable.
Animation, 11MB avi.
This circular cylinder is loaded under displacement control in shear+tension. This is an elasto-plastic model wit isotropic hardening and VUMAT explicit dynamic GTN implementation. The contour plot shows the volumetric void fraction (VVF) variable.
Animation, 10MB avi.
This is a single FE, 1st order 8-node brick with reduced integration, C3D8R from Abaqus element library. The element is loaded under displacement control in shear+tension. This is an elasto-plastic model with isotropic hardening and no damage, implemented in a UMAT implicit quasi-static user material subroutine. The contour plot shows U2 displacements, along Y. variable.
Animation, 5.2MB avi.
This is a single FE, 1st order 8-node brick with reduced integration, C3D8R from Abaqus element library. The element is loaded under load control in pure shear. This is an elasto-plastic model with isotropic hardening and no damage, implemented in a VUMAT explicit dynamic user material subroutine. The contour plot shows U2 displacements, along Y. variable.
Animation, 10MB avi.
A 3D model of a circular cylindrical rod loaded under displacement control in shear+tension. This is an elasto-plastic model with isotropic hardening and no damage, implemented in a UMAT implicit quasi-static user material subroutine. The contour plot shows PEEQ variable - equivalent plastic strain.
Animation, 9.3MB avi.