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

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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

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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

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• Computes stress

intensity factors

(SIFs) for

arbitrary 3D

crack geometry Part II

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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

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• 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

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• 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

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“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

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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

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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

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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

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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

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• 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

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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

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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

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Industry Example

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