end do
Here for simplicity, element matrices are assembled fully in the full
square global matrix. Since the global stiffness matrix is symmetric and
sparse, these facts are used to economize space and time in actual
finite element codes.56
Appendix B: Detailed explanation of single element (*inp
file)
This part demonstrates a practical single element example, which can be
used to generate any model in ABAQUS/Standard with the implemented
fracture model. The problem is a simple element subjected to uniaxial
tension. The present *inp file demonstrates an element with eight nodes,
in 2D, with material properties and twenty status variables. From this
point, the displacement, boundaries and the analysis are defined usually
as it is done in a normal input file. Moreover, putting a visualization
command in the ASSEMBLY section pointing to the UMAT elements for
post-processing purposes. 57,40
*Heading
*Preprint, echo=NO, model=NO, history=NO, contact=NO
*********************************
*NODE
1, 0.0,0.0
2, 1.0,0.0
3, 1.0,1.0
4, 0.0,1.0
5, 0.5,0.0
6, 1.0,0.5
7, 0.5,1.0
8, 0.0,0.5
*NSET, NSET=BOTTOM
1,2,5
*NSET, NSET=TOP
3,4,7
*NSET, NSET=MIDDLE
6,8
*NSET, NSET=EDGES
3,4,6,8
*NSET, NSET=ALLNODES
BOTTOM, TOP, MIDDLE
*AMPLITUDE, NAME=DIS
0.000,0.000,1.0,1.0
*********************************
*USER ELEMENT, NODES=8, TYPE=U1, PROPERTIES=6, COORDINATES=2,
VARIABLES=200
1,2
1,12
*ELEMENT, TYPE=U1, ELSET=TODOS
1,1,2,3,4,5,6,7,8
*********************************
*UEL PROPERTY, ELSET=TODOS
71660,0.3,345.0,0.0,407.5,0.25
*********************************
*ELEMENT, TYPE=CPE8, ELSET=dummy
2 ,1,2,3,4,5,6,7,8
*********************************
*Solid Section, elset =dummy, material=dummy
1.0
*Material, name=dummy
*Depvar
20,
*User Material, constants=2
1.0e-11,0.3
*********************************
*STEP, INC=10000000, EXTRAPOLATION=NO, nlgeom=NO
*STATIC, DIRECT=NO STOP
1.0E-3,1.0,1.0E-7,1.0E-3
*********************************
*BOUNDARY
BOTTOM, ENCASTRE
*BOUNDARY, TYPE=DISPLACEMENT
TOP,2,2,0.1
*********************************
*Restart, write, frequency=0
*Output, field
*element output, elset=dummy
Sdv21
*Node Output
RF, U
*Output, history, variable=PRESELECT
*Node Output, nset =top
RF2
*End Step
Appendix C: Umat &UEL Algorithmic
Paradigm