ABUMPACK - ABaqus User Material PACKage

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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.

Feedback and support

With any questions, bug reports, feedback and any other comments please submit a ticket.

Latest release

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.

Progress

JAN-2017 | NOV-2016 | JUL-2016 | MAR-2016

Publications

Ductile fracture surfaces

SEM images of ductile fracture surfaces of a thermomechanically controlled rolled (TMCR) steel, at different magnifications.

duct. fract. surf 1 duct. fract. surf 2 duct. fract. surf 3 duct. fract. surf 4 duct. fract. surf 5

old, c.2003, animations

EnSight and mpg files

CAFE

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.

SP1 resolved to 100, 110, 111 crystal planes, run 1. SP1 resolved to 100, 110, 111 crystal planes, run 2.

ABUMPACK examples

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.

The Charpy impact test

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.

GTN VUMAT Charpy test,
         Levenberg-Marquardt method

Animation, 7MB, avi.

Bar shear with damage

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.

GTN UMAT beam shear, Levenberg-Marquardt method

Animation, 9M avi.

Bar tension with damage

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.

GTN UMAT 3D tension, Levenberg-Marquardt method

Animation, 11MB avi.

Bar under shear+tension with damage

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.


rod, shear+tension, displacement control, elasto-plastic, isotropic hardening,
VUMAT, void volume fraction

Animation, 10MB avi.

Single FE in shear+tension, no damage

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.

single FE in shear+tension,
       elasto-plastic isotropic UMAT

Animation, 5.2MB avi.

Single FE in pure shear, no damage

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.


single FE, pure shear, elasti-plastic isotropic hardening, VUMAT

Animation, 10MB avi.

Elasto-plastic bar under shear+tension, no damage

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.


rod, shear+tension, displacement control, elasto-plastic, isotropic hardening

Animation, 9.3MB avi.

Other Fortran related projects

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