Transcript FRANC3D/ABAQUS Framework for Analysis of Interface

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Cohesive modeling in ABAQUS
1
3D Cohesive Element
n
through-thickness stress
[K] relates stress to separation
= {dn, ds, dt }/T0
t
transverse
shear
s
membrane
shear
Cohesive modeling in ABAQUS
2
Viscous Regularization
 - represents the relaxation time
D - stiffness degradation variable of the inviscid system
Dv - stiffness degradation variable of the viscous system
Important Assumption - the viscous system relaxes to the inviscid system
as t/
∞
Advantage - tangent stiffness matrix, during the softening regime, is
positive for small time increments
Linking FRANC3DNG and ABAQUS for interface
fracture
3
For all elements in mesh:
For all faces on element:
Store the element pair sharing the face and the face nodes
For all element pairs stored:
If element material id #s are different
Store bimaterial interface nodes and elements
For all interface nodes stored:
Create 2 duplicates of the node
For all interface elements stored:
Reconnect elements with duplicate nodes
Create interface elements
Verification and realistic models tested
4
Applied displacement = 0.015 inch
Traction, psi/inch
Material #1
100
1e7
Material #2
0.015
d, inch
Model results – compare with previous slide
5
d
x 0.015 inch
Viscous regularization for reduced computation time
6
Time to solve, seconds
125
120
115
110
105
100
95
90
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Viscosity parameter, 
0.08
0.09
0.1
Viscous regularization for reduced computation time
7
Through-thickness stress
400
350
u = 0.001
300
u = 0.01
250
u = 0.1
200
u = 0.05
150
u=0
100
50
0
0
0.2
0.4
0.6
Time
0.8
1
1.2
Additional items
8
Investigation of viscous regularization
solver technique to speed calculations has
been completed.
Currently working on code for the insertion
of a distribution of particles (locations and
sizes) into a matrix on the topological level.
Wish List
9
 From MD simulation, when does the crack grow along
the boundary and when does it nucleate?
20 