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FRANC3D Training Workshop:
Part II
Drs. Bruce Carter, Paul “Wash”
Wawrzynek, Tony Ingraffea, and
Omar Ibrahim
February - 2016
Fracture Analysis Consultants, Inc.
2
• General introduction to FRANC3D:
- capabilities and limitations
• Present theories and approaches to computational
fracture mechanics built into software
• Hands-on sessions give participants time to use
software
• Opportunity for participants to ask questions
Objectives
Part II
3
Workshop Agenda
• Part I: Introduction to Fracture Mechanics Analysis
• Part II: Introduction to FRANC3D
• Part III: FRANC3D FE model import - demo & hands-on
• Part IV: Crack Insertion Process – demo & hands-on
• Part V: Crack Growth and Fatigue Life – Theory, Rules & Models
• Part VI: FRANC3D crack growth, SIF history & fatigue life
- demo & hands-on
• Part VII: FRANC3D Session Log, Playback, Command Line & Python
• Part VIII: Known issues & what to do if something goes wrong
• Part IX: Capabilities coming soon
Part II
Introduction to FRANC3D
4 Part II
5
FRANC3D Development History
• 1988 to 1994
– FRANC3D v1.0 BEM only
• 1994 to 2001
– FRANC3D v2.0 BEM & Thin Shell FEM
• 2001 to 2005
– FRANC3D v3.0 BEM & Thin Shell & Solid FEM (ANSYS)
• 2005 to 2009
– FRANC3D v4.0 Solid FEM only (ANSYS, ABAQUS, NASTRAN)
– Completely new code written in C++
• 2009 to 2010
– FRANC3D v5.0 – Command line interface and other enhancements
• 2010 to 2014
– FRANC3D v6 – Fretting Fatigue, Fatigue Life, Post-processing & other enhancements
Part II
FRANC3D Development History
• 2015-16
– FRANC3D v7.0
• New geometric intersection engine for crack
insertion (increased robustness)
• Built in sub-model generation tool
• Expanded Fatigue Crack Growth Rate library
• Expanded automatic FCG stopping options
• Robust automatic method for fatigue life integration
• DARWIN-FRANC3D Interface
• Others
Part II 6
FRANC3D Version 7 Software
• FRacture ANalysis Code 3-D uses the finite element (FE)
method to simulate crack growth
• Designed to work in conjunction with commercial finite
element codes:
– ANSYS
– ABAQUS
– NASTRAN
7
• Computes stress
intensity factors
(SIFs) for
arbitrary 3D
crack geometry Part II
8
FRANC3D Software
• Adaptively remeshes 3D FE model to simulate crack
growth; uses explicit crack geometry
• Several elements used to model the crack front:
• Written in the C++
• Runs on Windows and Linux systems
• Programming interface that is an extension to the
Python programming language
Part II
9
• Inserts a flaw into an existing finite element (FE)
model and remeshes, using special crack-front
elements.
• Computes stress intensity factors (SIF’s) for all nodes
along a crack front for isotropic or anisotropic
materials.
• Predicts how a crack will grow (relative extension and
angle) using engineering growth criteria, and extends
the crack geometry and remeshes.
What Does FRANC3D Do?
Part II
10
• Not a general FE pre-processor or post-processor:
external software required to build uncracked FE models
and to visualize results (FRANC3D can display deformations).
• Not a FE analysis program:
external FE code is required (e.g., ANSYS, ABAQUS or
NASTRAN) to perform stress analysis.
• Not a “fast running” fatigue life prediction code with
stored analytical or table-look up K solutions (e.g.,
AFGRO, NASGRO or DARWIN).
What FRANC3D is NOT
Part II
11
“global”
model
“sub-model”
crack growth region
Global and Local “sub-model” Terminology
FE software (e.g., ANSYS) or FRANC3D can be used to define global and
sub-model. Sub-model should encompass the crack growth region with
‘space’ for remeshing. Part II
12
FRANC3D
FRANC3D Modifies the Sub-model
uncracked model after crack insertion
FRANC3D modifies the sub-model by
inserting a crack and remeshing.
A file that combines the global and sub-model
is output – and then analyzed by FE software.
Part II
13
mesh compatibility
FRANC3D Maintains Mesh Compatibility
FRANC3D retains surface meshes on “cut” surfaces for compatibility between
the global and sub-model – the best and preferred approach.
Note that FRANC3D can instruct the FE software to use constraint equations.
Part II
14
Re-Combined (Full Model) Analysis
FRANC3D does not use “global/local” solution approach (although it is
possible); FE analysis is performed with the full combined model. Part II
15
Crack Growth Process
after 21 steps of crack growth
Crack growth simulated by repeatedly reading and modifying initial
uncracked sub-model; do no remove or overwrite initial FE model files.
At each step, the global and modified local sub-model are re-combined,
and the full model is analyzed. Part II
16
• Development funded by:
– USA Air Force
– USA Navy
– NASA
– Customers
FRANC3D Software
• Customers include:
− US Air Force & Navy
− Siemens
− Pratt & Whitney
− Rolls Royce
− MHI
− Northrop Grumman
− Pilatus Aircraft
− Sandia Lab
− Fatigue Technology
− Honeywell Engines
− Sikorsky
− NASA
− others
Part II
FRANC3D Validation Examples
17 Part II
18
Benchmark Examples
Part II
Modified CT Specimens
• Compact Tension (CT) is a
standard fracture test specimen
which is a 2-D problem
modeled as 3-D.
• Third hole is bored in the
specimen which causes the
crack to curve depending on
where the third hole is placed,
the crack either grow into hole
or bypass the hole
Part II 19
Crack Trace on The Face of
Gear Tooth
Observed Simulated
20 Part II
21 Part II
Industry Example
Observed crack growth FRANC3D blind
prediction
Part II 22
Industry Example
• Three cracks inserted and propagated
45 steps of crack growth
completed
a
b
c
23 Part II
Industry Example
24 Part II