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Dr.- Ing. Paola Caracciolo
email: [email protected]
EFFECT OF DEFECT IN ADDITIVE
MANUFACTURING PRODUCTS International Conference on Additive Manufacturing & 3D PrintingAdded Scientific Ltd – Nottingham (UK), 10 July 2018
• State of Additive Manufacturing (AM)
Historical Evolution of Application within Airbus
First Certified Titanium Part on Civil Aircraft
AM serial production
• Research Activities
Probabilistic Fracture mechanics on AM parts
Defects types and method of detection
Test case –Process chain
• Considerations and Remarks
Summary
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
• Commonly known as “3D-Printing” is the process of joining
materials to make objects from 3D model data, usually layer
upon layer, as opposed to subtractive manufacturing
methodologies.
• AM utilized in aircraft manufacturers are rapidly evolving and
are introduced also in the new aircraft designs, as well as
retrofits and repairs.
• In the vision to widely utilize AM within the next 5-10 years, a
continued research improvement is a key enabler in 3D printing
processes.
State of Additive Manufacturing (AM)
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
First Certified Titanium Part on Civil Aircraft –600 patents per year
1st twin-engine widebody aircraft,
A300
1st full fly-by-wire commercial
airliner
1st double decker airliner, A380
1st manufacturer to make
extensive use of composites
Industry FIRSTS
3D Printing
Image shows the 1st flying
3D printed metal part
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Historical Evolution of Applications within Airbus
First Certified Titanium Part
on Civil Aircraft
First Optimised
Aluminium Structure
on Satellite
First EBM
Titanium
Structural Part
on Satellite
First Serial FDM
Polymer parts on
A350XWB
First use of SLA
models in Airbus
wind-tunnel
First SLS Polymer
Serial Parts on
Helicopters
Powder
Bed Fusion
Titanium
Directed Energy
Deposition
Titanium
Polymers
Composites
Powder Bed
Fusion
Aluminium
First Optimised
Aluminium RF Filter
on Satellite
First SLS Assembly
Tooling Applications
First application of SLS
to mitigate schedule
risk on flight test
First SLM
Titanium
Structural Part
on Satellite
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Optimised PartsPowder Bed
Fusion
Titanium
3-D design
Manufacturing
AM Serial Production
The AM process discusses the general steps
involved in most additive manufacturing (AM)
procedures:
• Creating 3D computer design models,
• Converting those models to AM compatible file
formats, setting up and running an AM
machine, part removal and post-processing.
• Topology optimization
• Implementation
integration
10 July 2018
Assembly Line
EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Research Activities
• AM is currently a comparatively expensive process, but this expense isacceptable in high-value applications where specialised materials areused or where it requires a complex design part.
• The design freedom meant that a significant proportion of weight couldbe saved in the part, while also reducing maximum stress and maintainingstiffness.
• As part of research into the benefits of AM manufacturing process, anAirbus A320 nacelle hinge bracket was optimized, incorporating atopology optimization method process.
• The fatigue and fracture analysis for Ti64 AM without HIP process forthe effect of defect in AM were investigated to identify the benefit ofprobabilistic damage technique.
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Probabilistic Fracture mechanics on AM parts
Can a probabilistic approach address porosities, inclusions, lack of fusion, and other imperfections in AM?
To share the needs for quantifying and managing uncertainties throughout the product lifecycle an investigate of commercial tools are
running and compared within a simulation process:
1. Fatigue Assessment of AM parts: A new computational Frameworks based on CT-
scans, Pro-Face (Polytechnic of Milan -IT, EU)
2. Design Assessment of Reliability with Inspection, DARWIN (South West Research
Institute, USA)
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Defects types & methods of detection
• Surface Quality
• Microstructure variability
• Powder Control
• Process Controls
>100 process parameters identified
Description & Formation
Foreign material in the part during
the manufacturing process. Foreign
material in feedstock powder or
metallization from heat shield
Impacts: mechanical
performance issue
Relevant Methods:
Destructive: Optical microscopy
NDT (Internal): X-Ray; CT; UT
Solid Inclusion
Description & Formation
Cracks from Residual Stress,
observed in the bulk material.
Micro-cracking caused by internal
residual stress
Impacts: initial flows, mechanical
performance issue
Relevant Methods:
Destructive: Optical microscopy
NDT (External) : ET - UT - Dye Penetrant
NDT (Internal): CT ; X-Ray
Cracks
Description & Formation
Porosity from entrapped gas inside
particles.
Entrapped gas porosity in the particles
Cause: issue with beam power distribution
(un-melted powder)
Impacts: mechanical performance issue
Relevant Methods:
Destructive: Optical microscopy
NDT : X-Ray; CT; UT
Gas CavitiesDescription & Formation
Material that has not been fused during
the process. Thicker layer of powder
due to recoating issue leading to partial
penetration of the beam. Potential fault
of the laser/electron beam.
Impacts: mechanical performance
issue, can initiate cracks during
fatigue cycling.
Relevant Methods:
Destructive: Optical microscopy
NDT (Internal): CT ; X-Ray
Lack of Fusion
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Test case: Process Chain
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
AIRBUS CONFIDENTIAL
Test case: Process Chain
Airbus Patents: 3D- SURFINEP000003109348A1, EP000003269848A1
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Computed Tomography
AIRBUS CONFIDENTIAL10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Distribution of maximum defect in the sample gage volume from CT •Extreme value statistics: maximum defect size in larger volumes is well estimated. • Validation measuring
critical defects (always surface or subsurface). • The applied stress intersects the Kitagawa diagram defining a distribution of critical defect size. • The Pf of every element is the
probability that the maximum defect is larger than the critical one. • The weakest link is applied to all the elements. •To evaluate the experimental results concerning the limit
depending on initial crack sizes, the data is plotted in a Kitagawa-Takahashi diagram.
Fatigue assessment of AM part (Pro-FACE)
( Polytechnic of Milan- IT (S. Beretta, S. Romano,, Int. J. Fatigue. 94 (2017) 178–191))
Pro-Face: based on the Kitagawa diagram extended to finite life
Local failure probability Local critical defect
10 July 2018
Design Assessment of Reliability with Inspection (DARWIN)The zone-based probabilistic fracture mechanics could provide improvements compared to conventional approaches and that it well suited for AM.
(Software code developed by Southwest Research Institute (SwRI )
Darwin Tool: based on fracture mechanics from initial defect size up to failure
Stress model
Probability of failure
“Stress-Life-Defect size”
relationship
CT scan
Defect distribution
10 July 2018
10 July 2018
Fatigue Test
EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Considerations and Remarks
• Probabilistic approaches should be implemented in case of failure of the deterministicmethod to address the missing issue without replacing traditional methods.
• In the study is emerged that a key input for the both probabilistic assessment is theanomaly distribution definition. How can we define it and what anomalies need to beconsidered and tackled by NDT and process control? (Crack initiation life from defects, Surfacedefect characterisation, anomaly distribution definition at coupon and part level etc…)
• Acceptable ranges of variation for the manufacturing parameters/materialanomalies distribution can be done using statistic distribution to determinate criticaldefect, propagation curve over all the crack regimes as well as propagation and stressthreshold.
• The study improve the optimization of design, the databases/allowable andhighlight limitation of AM quality with respect to industry specifications.
• Influence of different defect parameters on the fatigue resistance, further fracturemechanical investigations need to continued to be explored for new process.
10 July 2018 EFFECT OF DEFECT IN ADDITIVE MANUFACTURING PRODUCTS, Paola Caracciolo
Thank you