2018 nCode User Group Meeting Analysis of Additive Manufactured...• Powder Metallurgy Hot Isostatic Pressing (PM HIP) • Process to densify powders in a HIP furnace at high pressure

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HBM Prenscia: Public

2018 nCode User Group Meeting

February 28 ‐ March 1, 2018 – Novi, MI USA

© 2018 HBM


Fatigue Analysis of Additive Manufactured Metals

Dr. Andrew HalfpennyDirector of Technology – nCode Products

http://mocosubmit.com/wp‐content/uploads/2014/04/Generico_topology‐optimization.jpg

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• Worldwide AM business sector valued at $5.3B in 2015 and increasing rapidly.

• #1 focus recommendation for Lloyd’s Register Foundation:

• “the safety of systems containing 3D and 4D additive manufactured parts”

“Fatigue is a principal failure mode of structural AM components and is a hurdle to its general acceptance.”

Introduction

UK National Strategy for Additive Manufacturing / 3D Printing, September 2016http://www.amnationalstrategy.uk/

Lloyd’s Register FoundationForesight Review of Structural Integrity and Systems Performance, November 2015http://www.lrfoundation.org.uk/publications/structural‐integrity‐and‐systems‐performance.aspx

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• Additive manufacturing increase design freedom + reduce need for machining

• Attended several AM seminars this year, and all include topology optimisation• Many software vendors provide tools for structural topology optimisation

…it is not all about shape – material strength, and particularly fatigue performance are crucial!

Introduction

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Example Guidance Notes for certification and qualification

• “Additive manufacturing (AM) techniques have significant barriers to overcome in delivering a manufacturing process that produces consistent quality and safety.”

• “The acceptance criteria specified shall consider all reasonably foreseeable load cases (e.g. if the part is subject to dynamic loading, the fatigue performance shall be specified with the acceptance criteria).”

Introduction

Lloyd’s Register and TWI, March 2017http://www.lr.org/en/services/additive‐manufacturing/additive‐manufacturing‐guidance‐notes.aspx

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• First Additively Manufactured Part for Oil and Gas Certified by Lloyd’s Register

• Titanium gateway manifold for pipelines.

• Designed by Safer Plug Company (SPC), Surrey, England

• Built by the AM production company 3T RPD using powder bed fusion.

Oil and Gas

Innov Oil, Issue 57, October 2017https://www.innovoil.co.uk/highlights57

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• Norsk Titanium to deliver world’s first FAA‐approved, 3D‐printed, structural titanium components to Boeing

• A titanium structural component.

• Built by Norsk Titaniumusing wire‐based Rapid Plasma Deposition (RPD) process.

Aerospace (Boeing)

Aerospace Testing International, April 2017http://www.aerospacetestinginternational.com/news.php?NewsID=84929

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• Airbus completed installation of titanium 3D‐printed bracket on an in‐series production A350 XWB.

• Titanium bracket, part of aircraft pylon, junction section between wings and engines.

• Built using additive‐layer manufacturing (ALM).

Aerospace (Airbus)

Aerospace Testing International, September 2017http://www.aerospacetestinginternational.com/news.php?NewsID=84929

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• “Net shape” Hot Isostatic Pressing project targetting large aerospace engine components

• Engine casing from nickel super alloy (IN718)

• Manufactured using Net Shape Hot Isostatic Pressing of powder (NSHIP)

• Manufacturing Technology Centre, UK The University of Birmingham, UKCEIT, Spain

Powder Metal HIP

Powder Metallurgy Review, September 2016http://www.pm‐review.com/net‐shape‐hot‐isostatic‐pressing‐project‐targets‐large‐aerospace‐engine‐components/

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• Patient received 3D printed titanium hip

• 3D printed titanium hip implant2014

Biomedical

The Engineer, May 2014https://www.theengineer.co.uk/issues/may‐2014‐online/patient‐receives‐3d‐printed‐titanium‐hip/

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• Material: Titanium Alloy “Ti‐6Al‐4V”• high strength, high stiffness to weight ratio, excellent corrosion resistance

• used in aerospace, automotive, oil & gas, biomedical and other industries

• one of the most commonly used titanium alloys

• Tensile and Fatigue Test Results for different manufacturing methods1. wrought bar and sheet

2. powder metallurgy hot isostatic pressing (PM HIP)

3. additive layer manufacturing by powder bed fusioni. selective laser melting (SLM)

ii. electron beam melting (EBM)

Objectives

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• Purpose of this presentation: 1. To show that fatigue testing is important

2. To obtain mechanical properties of a “material” for use in design and analysis

• “material” considers an “holistic material”: ‐ raw material‐ manufacturing method‐ machining‐ heat treatment‐ surface treatment‐ fabrication / joints / welds

• The purpose of this presentation is NOT to promote a manufacturing method above or below another

• each have their own advantages and disadvantages

• a successful product requires many things; including an appropriate material, design and manufacturing method to meet operational requirements

Objectives

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• Powder Metallurgy Hot Isostatic Pressing (PM HIP)• Process to densify powders in a HIP furnace at high pressure (100‐200 MPa) and

temperature (900 ‐ 1250°C). Gas pressure acts uniformly in all directions to provide isostatic properties and 100% densification.

• “PM HIP case studies.pdf” ‐ from https://www.epma.com/hot‐isostatic‐pressing

• Powder Bed Fusion (PBF)• Thermal energy selectively fuses

regions of a powder bed

• Two common types:

i. selective laser melting (SLM)

ii. electron beam melting (EBM)

• Combinations • HIP is used as a post‐processing method to improve fatigue properties of SLM and EBM

manufactured material.

Method

“SI Performance of AM Ti Alloys”, ZhangRAeS Conference, AMRC Sheffield, 5 April 2017

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• EBM has highest Yield and UTS• Bar and PM HIP are very similar; for both Yield and UTS• Sheet has high Yield and UTS, and has high “AR” variability

(probably due to location in the sheet and localised differences in grain stretching)

Results : Tensile Tests : UTS

Cyclically Stabilised

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• EBM has highest Yield and UTS• Bar and PM HIP are very similar; for both Yield and UTS• Sheet has high Yield and UTS, and has high “AR” variability

(probably due to location in the sheet and localised differences in grain stretching)

Results : Tensile Tests : Yield Strength


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• Bar and PM HIP are very similar; for both Yield and UTS• SLM Yield and UTS are higher than Bar and PM HIP, but lower than Sheet• Sheet has the highest Yield and UTS

(probably due to the additional rolling and grain stretching)

• Including comparison with Figure 5 from Metal Additive Manufacturing: A Review of Mechanical Properties, John J. Lewandowski and Mohsen Seifi, April 2016

Conclusions : Tensile Tests

0 MPa

1000 MPa


Metal AM: A Review of Mechanical PropertiesJohn J. Lewandowski and Mohsen Seifi

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• Geometry

• Polished gauge section

• Test Condition• Room temperature

• Strain controlled

• Sinusoidal waveform ( constant amplitude )

• Fully reversed ( R‐ratio = ‐1 )

• Failure Criteria• 20% load drop

Method : Fatigue Tests

Supplied As Gauge Length (mm)

Diameter (mm) or Thickness / Width

Bar 65mm bar stock 10 7

Sheet 4mm sheet stock 8 4 / 8 and 1.5 / 8

PM HIP 14mm square section blocks 8 6

SLM 13mm bar 10 6

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• Stock: 65 samples from 3 batches (4mm sheet, 65mm bar [2 batches])

Results : Fatigue Tests

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• EBM : 15 samples• Low scatter • Lower life than stock but generally within 3• Notable increase in b slope


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• PM HIP : 25 samples• Significant scatter• Lower life than stock but generally within 3• No significant change in b slope


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• SLM : 2 samples (very low sample size)• Lower life than stock by more than 3


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• AM generally have lower life than stock

• Modern HIP process can generally bring life to within 3

• Material testing and characterisation are essential for both power metal and manufacturing process

Cannot rely on wrought stock data for fatigue modelling!

Can use Strain‐Life (EN) approach in the case of Ti6AL‐4

Conclusion : Fatigue Tests

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• Strain‐Life fatigue testing base material

• PM HIP

• EBM

• SLM Testing in progress

• WAAM ( 2018 to 2022 : supporting a University led EPSRC grant application )(Wire‐Arc)

• Component validation • Small component test cases to physically test and compare with strain‐life fatigue

prediction

Further Work

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c ab

• Build orientation

• Understand how build orientation affects fatigue performance

• Fatigue curves for each orientation

• Should AM structural simulation and fatigue analysis always use the “weakest” build orientation?

• Composites use directional properties…

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c ab

c ab

Further Work

• Surface finish

• Fatigue cracks initiate at a free surface.

• Current fatigue tests are best casemachined and polished from “printed” bar

• Fatigue curves for “as‐printed” gauge section.( including any post‐build treatments )

• How do they compare?

With a structurallyoptimised topologyit may be very difficultto improve the surface finish

© 2018 HBM


www.hbmprenscia.com

Dr. Andrew Halfpenny

Director of Technology – nCode Products

[email protected]


Documents

2018 nCode User Group Meeting Analysis of Additive Manufactured...• Powder Metallurgy Hot Isostatic Pressing (PM HIP) • Process to densify powders in a HIP furnace at high pressure