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03_fracture
EFG and XFEM Cohesive Fracture Analysis
Methods in LS-DYNA
Yong Guo*, Cheng-Tang Wu
Livermore Software Technology Corporation
LS-DYNA Seminar
Stuttgart, Germany
November 24, 2010
LS-DYNA Seminar 2
1. Overview on Failure/Crack Simulations
2. EFG and XFEM Cohesive Fracture
Methods
3. Numerical Examples
4. Conclusions
Outline
LS-DYNA Seminar 3
1. Overview on Failure/Crack
Simulations
Tie-break Interface
Force/stress-based failure + spring element, rigid rods, or other constraints
Suitable for delamination, debonding, known weak areas
Element Erosion
Stress/strain-based failure + contact force
Loss of conservation, strong mesh dependence and inadequate accuracy
Cohesive Interface Element
Cohesive zone model + interface element + contact force
Crack along interfaces: Mesh dependence
EFG
Cohesive zone model + moving least-square + EFG visibility
XFEM
Cohesive zone model + level sets + extended finite element
LS-DYNA Seminar 4
2. EFG and XFEM Cohesive Failure
Methods
EFG and XFEM Failure Analysis
Both are discrete approaches (strong discontinuity).
Crack initiation and propagation are governed by cohesive law
(Energy release rate).
Crack propagates cell-by-cell in current implementation.
EFG is defined by visibility; XFEM is defined by Level Set.
Minimized mesh sensitivity and orientation effects in cracks.
Applied to quasibrittle materials and some ductile materials.
EFG for Solid with 4-noded integration cells.
XFEM for 2D plain strain and shells.
LS-DYNA Seminar 5
2.1 EFG Cohesive Failure Method
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