Simulation of Advanced Processes: Welding & Additive Manufacturing Cases Studies

VIRFAC | The Virtual Factory
Finite Element Simulation of
Advanced Processes
Case Studies:
Welding & Additive Manufacturing
Copyright GeonX © 2014 Dr. Laurent D’Alvise
CEO & co-founder
www.geonx.com
sales@geonx.com

TABLE OF CONTENTS
Cladding
example
Welding
example
Global
picture

Virfac® | www.geonx.com
 To control parts deformations during manufacturing …
 Improving quality mastering before launching production !
 To control residual stresses generated during manufacturing …
 Assessing the impact of manufacturing on life and durability !
 To understand the complex phenomena occurring during manufacturing and
the influence of process operating conditions …
 Reducing scrap and improving cash return !
WELDING SIMULATION : WHY ?
© 2012-2014 GeonX – All rights reserved

OUR VISION
 Physics simulation and modelling will help achieving these goals
 GeonX is building the integrated Virtual Factory that will enable production
engineers to simulate before making !
 NOT an expert tool for expert engineers
 BUT a powerful software tightly integrated with manufacturing
machines and modern computing capabilities.

LET’S TAKE AN EXAMPLE !
Virfac® | www.geonx.com © 2012-2014 GeonX – All rights reserved
INPUT DATA
 From: Tanker
 Components: 2 Stiffened Panels (AH36)
 Dimensions: 3,48 x 16 m
 Thickness: 13 mm
 Weld Length: 16 m
 Objective: control distortions

 Live visualization of temperature, deformations,
stresses, metallurgical transformations, etc.
TYPICAL OUTPUTS

1
-6
Y [mm]
TYPICAL OUTPUTS
 Final deformation of the stiffened panels after 1 weldline operation.
 Possibility to optimize the welding sequence, operating conditions, clamping
system, jig positions, etc. in order to minimize deformations.
 Particularly well suited when the structure is complex and with a high number
of welds.

VIRTUAL WELDING, OR
ADVANCED WELDING SIMULATION
Welding objectives:
• Minimization of distortions
• Minimization of residual stresses (crack prediction)
• Optimization of weld joint properties (hardness) and microstructure
• Verification of weldability or defaults
Operating conditions to tune/optimize:
• the welding speed/energy
• the welding sequence
• the clamping or fixture setup
• and other operating conditions, if any
OUT
IN
IN
Virtual
Welding
OUT

Private Belgian company incorporated in October 2012
Specialized scientific and industrial software editing
Development of a new generation manufacturing software:
• The Virtual Factory, Virfac® powered by Morfeo: powerful user-interface (since 2012)
• Morfeo (Manufacturing ORiented Finite Element tOol): parallel FE solver (since 2003 in partnership with Cenaero)
The Virtual Factory Virfac® addresses the following processes:
•Fusion & Friction Welding (LBW, EBW, FSW, IFW, etc.)
•Additive Manufacturing (Cladding, etc.)
•Advanced Machining
•Damage tolerance and durability
•Welding → In-service behavior (crack propagation)
•For large industrial mechanical components
•Specifically designed for High Performance Computing systems
•Extensively tested on industrial and demanding applications
•Within the industrial environment (mimetic)
GEONX IN A NUTSHELL

GEONX SOFTWARE PRODUCT
Morfeo Virfac®

VIRFAC® IN A NUTSHELL
CAD modelling
 Parasolid kernel library (Siemens PLM)
 Import and export of Parasolid native file (x_t, xmt_txt, xmt_bin, x_b, …)
 Model transformation (intersection, union, scaling, rotation, translation, etc.)
 CAD geometry entities management (creation, destruction, …)
 Import of other CAD format: translators for CATIA, Pro-E, IGES and STEP
 Discrete model importer with cleaning functionalities
Meshing:
 DISTENE MeshGems on Parasolid model for :
 Surface triangulation
 3D tetrahedra meshing
 Size control – Face – Edge – Node – Curvature
 Anisotropic meshing
 Extruded unstructured meshes
 Partnership with Beta-System (ANSA mesher)

The present study aims to:
1. Use Virfac Welding for an application representative aerospace interests
2. Simulate the welding process on a exhaust carter and display distortions taking place
during the welding operations
3. Verify the influence of the welding sequence on the residual distortions
4. Compare two modelling approaches from a computing performance and accuracy
standpoints
Welding
sequence n°1
Welding
Sequence n°2
Transient Thermo-
Mechanical analysis
Inherent Strain
Method
EXAMPLE N°1 - OBJECTIVES

A “fake” exhaust carter was designed for non-confidentiality purposes:
1. External diameter : 200 mm
2. External ring thickness : 12 mm
3. Number of welds : 16
4. Nominal sequence: shown hereafter
APPLICATION DESCRIPTION

Experimental data:
1. Material : steel
2. Clamping system : central core
3. Welding process : LBW
4. Welding power : 800 W
Nominal welding sequence:
1. Distortions are magnified 40 times
2. External ring strongly deformed
3. Visible rotation of the part
4. Twist of the carter
5. Computation time: 21 minutes
RESULTS

Influence of the operating conditions:
1. Welding parameters
2. Clamping system
3. Welding sequence
MINIMIZATION OF DISTORTIONS

Influence of the welding sequence:
MINIMIZATION OF DISTORTIONS

Influence of the welding sequence:
Changing the welding sequence leads to a reduction of distortions:
• This information may be useful to address quality issues
• This information is available through a virtual environment prior any experimental test
• Timeframe for obtaining such results on this simple application:
 Set the model with Virfac: ~4 hours
 Computation time: 21 minutes per simulation
• Process optimization is possible within a virtual environment: Virfac Welding Scheduler
• Further results in terms of residual stresses and metallurgy are also possible:
full transient methodology : Virfac Welding Designer
PROCESS OPTIMIZATION

The present lecture aims to:
1. Apply Virfac to laser cladding simulation and predict distortions after corrective
machining.
2. Demonstrate the feasibility and pertinence of manufacturing chaining simulation.
3. Perform sensitivity studies on the operating conditions and check the influence on
quality criteria in terms of residual distortions.
EXAMPLE N°2 - OBJECTIVES

Machining
Simple (for validation purposes) additive manufacturing application (laser
cladding: tube on support) followed by machining.
Additive Layer
Manufacturing
Distortions, Residual
Stresses and
Metallurgy from the
T/M/M simulation
Final part
within
geometrical
tolerances
APPLICATION DESCRIPTION
• Large excursions of temperature
• Cycling heat load over one location
• Cycling material melting & solidification
• Large excursions of material properties
• Important metallurgical transformations
Export :
• Final geometry
• Residual stresses

MA
-
Corrective
Machining
The present study aims to setup a demonstrator of process chaining simulation.
The following questions will be addressed:
1. How far the ALM part will be from the nominal geometry ?
2. How will the machining process influence the distortions of the final part ?
3. Which tolerance will be reached after machining ?
Important notice: this numerical model will be used as a simulation demonstrator
and not yet for experimental validation purposes (see perspectives).
ALM
-
Additive Layer
Manufacturing
WORK PLAN

Additive Layer
Manufacturing
Stage n°1: Additive Layer Manufacturing
1. Operating conditions:
 Tube on plate: ext.diam. 52.4 mm, length 25 mm, thickness 2.2 mm
 Material: Inconel 718
 Number of cladding layers: 14
 Loading speed: 13.3 mm/s
 Loading time: 172 s
 Post-ALM cooling time (on threshold 20°C): 1579 s
2. Modelling hypothesis:
 Thermo-Mechanical-Metallurgical coupling
 Transient analysis
 HEXAhedra elements conforming to the clad
 Automatic mesh elements’ activation according to a moving box of selection
 Heat loading: energy density applied in the activated FE elements (volume)
 Thermal properties as a function of temperature
 Mechanical properties as a function of temperature (Elasto-Plastic # Power Law)
 Distributed Multi-Processing analysis: 12 processors
SIMULATION DESCRIPTION - ALM

ALM sequence:
 Same starting point for each layer
 Same loading direction for all layers
SIMULATION RESULTS - ALM

Residual distortions (after ALM + cooling):
 Comparison against the nominal geometry
 Cross section parallel to the ALM start
 Deflection at the top of the tube: -0.637 mm
 Maximum deflection (radial): -0.755 mm
δtop = -0.637 mm
δmax = -0.755 mm
Cross section

Alternative layer sequences:
Influence on residual distortions
Configuration T2:
 Same start for each layer
 Alternating loading direction
from one layer to the next
Configuration T3:
 90° shift start for each layer
 Same loading direction for
all layers
Configuration T4:
 90° shift start for each layer
 Alternating loading direction
from one layer to the next
i
i+1
i
i+1

i
i+1Cross section
δtop = -0.475 mm
δmax = -0.594 mm
Reference (configuration T1):
δtop = -0.637 mm
δmax = -0.751 mm
Configuration T2:

δtop = -0.66 mm
δmax = -0.747 mm
Cross section
δtop = -0.637 mm
δmax = -0.751 mm
Configuration T3:

δtop = -0.577 mm
δmax = -0.700 mm
Cross section
i
i+1
δtop = -0.637 mm
δmax = -0.751 mm
Configuration T4:

Additive Layer
Manufacturing
Stage n°2: Machining
1. Operating conditions:
 Tube on plate: deformed from the Additive Manufacturing process
 Geometry: Configuration T2 selected
 Machining process: surface finish (cylindrical shape)
 Thickness of removed material: 0.2, 0.4, 0.6 mm
 Objective: flat surfaces
2. Modelling hypothesis:
 Deformed mesh from the upstream analysis (ALM)
 Residual Stresses mapped from the upstream process (ALM)
 Mechanical analysis based on XFEM
 Cutting passes represented by Level-Sets
 Computation time : several minutes
Machining
Mesh’’
MODELLING DESCRIPTION

Machining thickness sensitivity:
 Effect of machining on residual distortions
 Without Stress Relief Heat Treatment
 The 0.6 mm thickness leads to flat external surfaces
Thickness
(mm)
Rtop
(mm)
Rmin
(mm)
Tolerance
(mm)
0.2 25.882 25.775 0,107
0.4 25.798 25.776 0.022
0.6 25.592 25.599 0.007
i
i+1Cross section
Additive Layer
Manufacturing
Machining
Flat surface
SIMULATION RESULTS - MA

FURTHER DETAILS
Contact details
Dr. Laurent D’Alvise
Mail: sales@geonx.com
Skype: geonx_
Visit: www.geonx.com
Follow us on Twitter: @geonx_

Simulation of Advanced Processes: Welding & Additive Manufacturing Cases Studies

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