ML20344A424
| ML20344A424 | |
| Person / Time | |
|---|---|
| Issue date: | 12/10/2020 |
| From: | Gorelik M NRC/NRR/DNRL/NVIB, US Dept of Transportation, Federal Aviation Admin (FAA) |
| To: | |
| Anchondo I | |
| Shared Package | |
| ML20344A421 | List: |
| References | |
| Download: ML20344A424 (39) | |
Text
Federal Aviation Administration Presented at:
NRC Workshop on Advanced Manufacturing Technologies - Session 6 December 10, 2020 Presented by:
Dr. Michael Gorelik FAA Chief Scientist and Technical Advisor for Fatigue and Damage Tolerance Regulatory Considerations for AM and Lessons Learned for Structural Alloys
Federal Aviation Administration BLUF (bottom line upfront)
- Leverage experience with other relevant material systems and historical lessons learned
- However need to consider unique / AM-specific attributes, especially for high-criticality components
- Increasing role of public standards
- Increasing role of Computational Materials / ICME 2
The same message as in 12/09/20 presentation
Federal Aviation Administration FAA Regulatory Documents 3
Rules 14 CFR Part XX Advisory Circulars Policies Issue Papers General Memoranda Means of Compliance (MoC)
SDOs
Federal Aviation Administration H.R. 302 FAA Reauthorization Act of 2018 4
SEC. 329. PERFORMANCE-BASED STANDARDS.
The Administrator shall, to the maximum extent possible and consistent with Federal law, and based on input by the public, ensure that regulations, guidance, and policies issued by the FAA on and after the date of enactment of this Act are issued in the form of performance-based standards, providing an equal or higher level of safety.
Federal Aviation Administration Engagement with SDOs and Consortia 5
FAA SAE ASTM MMPDS AWS AIA America Makes AMSC KART AMC A partial list SDOs Consortia / WGs CMH-17
Federal Aviation Administration Some AM-Specific Attributes
- Characterization and role of inherent (and rogue) material anomalies / defects
- Anisotropy
- Location-specific properties
- Residual stresses
- High process sensitivity / large number of controlling parameters
- Effects of post-processing (HIP, heat treatment, surface improvements, )
- Material-specific NDI considerations
- Effect of surface conditions
- Susceptibility to environmental effects 6
- Each individual category has been encountered in other material systems
- Unique nature of AM - all of these categories apply
Federal Aviation Administration FAA Regulatory Environment (driven by different product types)
Small Airplanes (14 CFR Part 23)
Engines and Propellers (14 CFR Parts 33, 35)
Rotorcraft (14 CFR Parts 27, 29)
Transport Airplanes (14 CFR Part 25) 7
Federal Aviation Administration 14 CFR Part 25 Regulations - Materials (Transport Category Aircraft)
§ 25.613 Material Strength Properties and Design Values a)
Material strength properties must be based on enough tests of material meeting approved specifications to establish design values on a statistical basis.
b)
Design values must be chosen to minimize the probability of structural failures due to material variability.
d)
The strength, detail design, and fabrication of the structure must minimize the probability of disastrous fatigue failure, particularly at points of stress concentration.
8
Federal Aviation Administration 14 CFR Part 25 Regulations - Special Factors (Transport Category Aircraft)
§ 25.619 Special Factors The factor of safety prescribed in § 25.303 must be multiplied by the highest pertinent special factor of safety prescribed in §§ 25.621 (Casting Factors) through 25.625 for each part of the structure whose strength is a)
Uncertain; b)
Likely to deteriorate in service before normal replacement; or c)
Subject to appreciable variability because of uncertainties in manufacturing processes or inspection methods 9
Federal Aviation Administration
§ 25.571 Damagetolerance and fatigue evaluation of structure (a) General. An evaluation of the strength, detail design, and fabrication must show that catastrophic failure due to fatigue, corrosion, manufacturing defects, or accidental damage, will be avoided throughout the operational life of the airplane.
Excerpts from 14 CFR 25.571 (Transport Category Aircraft) 10
Federal Aviation Administration AC 29-2C on Flaw Tolerance (Transport Category Rotorcraft)
To determine types, locations, and sizes of the probable damages, considering the time and circumstances of their occurrence, the following should be considered:
- Intrinsic flaws and other damage that could exist in an as-manufactured structure based on the evaluation of the details and potential sensitivities involved in the specific manufacturing work processes used.
The flaw sizes to be considered should be representative of those which are likely to be encountered during the structures service life resulting from the manufacturing, maintenance, and service environment.
An analysis may be used combining the distribution of likely flaw sizes, the criticality of location and orientation, and the likelihood of remaining in place for a significant period of time.
11
Federal Aviation Administration AC 29-2C on Inspections (Transport Category Rotorcraft)
- The specific inspection methods that are used to accomplish fatigue substantiation should be:
- Compatible with the threats identified in the threat assessment, paragraph f.(5), and provide a high probability of detection in the threat assessment and their development, under the operational loads and environment.
12
Federal Aviation Administration Excerpts from 14 CFR 33.70 (Aircraft Engines)
- WHY: Industry data has shown that manufacturing-induced anomalies have caused about 40% of rotor cracking and failure events
- WHAT: 33.70 rule requires applicants to develop coordinated engineering, manufacturing, and service management plans for each life-limited part
- This will ensure the attributes of a part that determine its life are identified and controlled so that the part will be consistently manufactured and properly maintained during service operation Engineering Plan Manufacturing Plan Service Management Plan The probabilistic approach to damage tolerance assessment is one of two elements necessary to appropriately assess damage tolerance.
AC 33.70-1, GUIDANCE MATERIAL FOR AIRCRAFT ENGINE LIFE-LIMITED PARTS REQUIREMENTS, 7/31/2009.
13
Federal Aviation Administration History is a Vast Early Warning System Norman Cousins 14 Lessons Learned What to Do?
What Not to Do?
Federal Aviation Administration Relevant Material Technologies - Examples
- Structural Castings
- Empirical life management system (design knock-downs, NDI acceptance criteria etc.)
- Effect of material anomalies understood, but not well quantified
- Powder Metallurgy (PM)
- Gave rise to PM-specific fatigue and DT methodologies, explicitly accounting for the presence of inherent material anomalies
- Forgings
- Process controls (lessons learned), advanced NDI
- Location-specific microstructure and residual stresses
- Welding
- Highly process-sensitive
- Susceptible to manufacturing anomalies
- Defects detectability challenges Plan to leverage regulatory experience with other process-sensitive material systems 15
Federal Aviation Administration Lessons Learned Powder Metallurgy (PM)
- Effect of defects may not be well understood for new technologies
- Transition from well-controlled development environment to full-scale production may introduce new failure modes
- Solution: development of adequate process controls, NDI and PM-specific life management system explicitly accounts for material anomalies (via probabilistic fracture mechanics)
Outcome: Several decades of successful field experience 16
Federal Aviation Administration Lessons Learned Structural Castings
- Empirical - effects of material anomalies are not well understood or quantified no explicit feedback loop to process controls and QA
- No means to assess / quantify risk
- May be overly conservative in some cases 17
Federal Aviation Administration Question Can we do better for AM..?
18 Performance = f (microstructure l anomalies population)
Federal Aviation Administration Example: Modeling Framework for Castings Simulate Casting Process and Porosity Porosity Results FEA Code FEA Model run using elastic properties as function of porosity field, and porous metal plasticity to predict fracture Linking Modeling Tools to Predict Stress/Strain, Fracture and Fatigue Life Post-processing for FEA Nodal values of porosity for use in FEA as a field variable Post-processing for Fatigue Analysis Fatigue Analysis Tools Multiaxial fatigue life prediction using location-specific fatigue properties as a function of local porosity FEA post-processing code to generate location-specific (nodal) fatigue property data Casting solidification model Directly Measure Porosity Courtesy of Prof. C. Beckermann (U. of Iowa)
CT scan porosity data Design Requirements (Strength)
Design Requirements (Fatigue)
Region of concern with porosity R. A. Hardin, C. Beckermann, Integrated design of castings: effect of porosity on mechanical performance, IOP Conference Series: Materials Science and Engineering, Vol. 33, 2012.
19
Federal Aviation Administration AM Part Zoning and Probabilistic DT Lack of Fusion Gas Porosity AM parts are uniquely suited for zone-based evaluation Concept is similar to zoning considerations for castings however, modeling represents a viable alternative to empirical casting factors One Assessment Option - PFM *)
- ) PFM - Probabilistic Fracture Mechanics
Reference:
M. Gorelik, Additive Manufacturing in the Context of Structural Integrity, International Journal of Fatigue 94 (2017), pp. 168-177.
20
Federal Aviation Administration Design Allowables Considerations 21 PIM = Process Intensive Materials
- Generation of design allowables is contingent upon mature material and process specifications
- Cross SDOs and WGs collaboration is essential
Federal Aviation Administration Material Allowables vs. Design Values 22 Credit: M. Shaw (GE Additive), presented at the 2018 Joint FAA - EASA Workshop on Q&C of Metal AM Parts, Wichita, KS, Aug. 2016.
- Top 2 curves -
bulk material allowables
- Bottom (red) curve - design values
Federal Aviation Administration 23 Part vs. Coupon Properties Property of Interest Property of Interest This understanding can be enabled by physics-based ICME models Finished AM Part Purpose-built Coupon
Federal Aviation Administration Example: Industry Lessons Learned 24 Developed by AIA RoMan Working Group
- Leveraged industry experience to reduce the likelihood of manufacturing-induced defects
- Emphasizes the role of real-time process monitoring systems for conventional (i.e. subtractive) manufacturing processes
Federal Aviation Administration Recent Developments
- Consortia / SDOs / Industry engagement
- R&D
- 2020 FAA-EASA Workshop on Q&C of AM (appendix) 25
Federal Aviation Administration Examples of External Engagements 26 AIA AM WG MMPDS ETTG Volume 2
- Guidance
- Data Emerging Technologies Task Group (Consortia and WGs)
Federal Aviation Administration 27 AIA AM Working Group Report:
Recommended Guidance for Certification of AM Component 2/28/20 https://www.aia-aerospace.org/report/certification-of-am-component/
Federal Aviation Administration 28 AIA AM Working Group Report (cont.)
Federal Aviation Administration
MMPDS recognizes the need to be proactive and keep pace with the rapid development of Emerging Metallic Structures Technologies by industry, e.g., Additive Manufacturing (AM), Friction Stir Welding (FSW) that are considered PIM.
Several efforts of PIM were presented to the MMPDS for allowables development but were found not to be compatible with current handbook procedures. Extensive amount of standardization efforts need to take place before design values for PIM can be considered for inclusion in the current handbook.
General agreement within the MMPDS to create two Volumes:
Volume I - Current handbook for traditionally produced Materials.
Volume II - Properties for PIM,e.g., Additive Manufacturing (AM),
Friction Stir Welding (FSW).
Emerging Technology Task Group (ETTG) was established to develop processes and procedures best suited to derive and publish design information for PIM Volume II.
MMPDS Efforts to Address Emerging Metallic Process Intensive Materials (PIM)
MMPDS and Additive Manufacturing
Federal Aviation Administration Emerging Technologies Task Group (ETTG) and its Working Groups ETTG - Michael Gorelik (FAA) & Sam Cordner (NASA)
Data Generation &
Applications D. Hall (Battelle) & A.
Steevens (Boeing)
Materials & Machines S. Cordner (NASA) & P.
Sodouri (Nork Titanium)
Certification &
Qualification R. Grant (FAA) & P.
Guerrier (MOOG)
Data Submission Guidelines -9.2 Data Analysis -9.5 Design Philosophy -1 & 9 Acceptance/Equivalence Testing -10.5 Influence Factors -1 SPC Methods -10.10 Specification Content Requirements -9 Material Qualification -9 or 10 Machine Qualification -9 or 10 SPC Requirements -10 Outline an approach to Further Showing -10 OEM & Component Supplier perspectives Part Qualification -10
Federal Aviation Administration MMPDS Interaction with SDOs and Working Groups ASTM Testing Specs AM Material Specs Signed MOU with Battelle SAE
- AM Material and Process Specs (AMS-AM)
- Use of MMPDS data analysis tools for spec min values AIA AM WG Developing best practices for Q&C of metal AM parts CMH-17 AM WG Cross-coordination to explore synergies and streamline communication between two groups AWS
- Welding Specs
- AM Specs
Federal Aviation Administration R&D - Internal / External
- Development of material databases (joint with DoD and NASA) - JMADD
- Seeded defects studies - effect of defects
- Understanding of process variability drivers
- Round-robin studies
- NASA ULI (University Leadership Initiative)
- CM4QC Steering Group - see next slide 32
Federal Aviation Administration D R A F T Co-organizers: NASA and FAA Membership Government Industry Academia NIST Boeing Carnegie Mellon AFRL Lockheed-Martin / Sikorsky UTSA Sandia NL Raytheon / P&W Vanderbilt NAVAIR GE Aviation Penn State ORNL Spirit Aerosystems Northwestern Army Aviation Honeywell Aerospace Howmet Aerospace SwRI Northrup-Grumman Textron Aviation / Bell Example: Development of Computational Materials (CM) Capabilities for Metal AM
Federal Aviation Administration Summary 34 Improved Inspection Methods Improved Manufacturing Process Controls Enhanced Life Management Plan (including DT)
- What worked well historically to reduce the rate of failures induced by material /
manufacturing anomalies a three-prong approach:
better capability to find anomalies better capability to prevent anomalies better capability to design for anomalies
Federal Aviation Administration Dr. Michael Gorelik Chief Scientist, Fatigue and Damage Tolerance Aviation Safety Federal Aviation Administration michael.gorelik@faa.gov (480) 284-7968 Discussion 35
Federal Aviation Administration APPENDIX 36
Federal Aviation Administration Workshop Demographics 37 Austria Belgium Brazil Canada France Germany Italy Netherlands Norway Poland Portugal Singapore Spain Sweden UK US 3%
57%
5%
28%
7%
Workshop Participation Academia Industry Machine makers Government SDOs and Non-Profit 16 Countries over 300 participants 3rd Joint FAA - EASA AM Workshop November 2-6, 2020 https://www.faa.gov/aircraft/air_cert/step/events/2020_additive_mfg_workshop/
Federal Aviation Administration Workshop Evolution 2018 2020 (joint FAA-EASA workshops) 38 2018 Workshop
- First joint FAA - EASA workshop
- First workshop with parallel breakout sessions
- Continued focus on Q&C
- Tracking of the key industry trends (in the Q&C context)
- Gradual increase in the industry demographics by segment 2019 Workshop 2020 Workshop
- Continued breakout sessions
- Significant participation from operators, Tier 2/3/ suppliers and machine makers
- Clear signs of Q&C framework maturation and common technical approaches
- Leveraged Machine Makers -
End Users knowledge transfer workshop
- First virtual workshop
- More balanced international participation
- More than 2x increase in participation
- Continued breakout sessions
- Focus on new technical developments, not organizational updates
- Highly diverse industry demographics
- Big focus on standardization
Federal Aviation Administration Agenda at a Glance Opening remarks:
Ms. Di Reimold, Deputy Director of Policy and Innovation Division, FAA Keynote - SpaceX Dr. Charlie Kuehmann, VP of Materials Engineering and NDE Mr. Will Heltsley, Vice President of Propulsion Engineering 22 presentations from the industry, government, academia and SDOs / Consortia / WGs 3 Breakout Sessions Standardization Day Regulatory Panel 39
- 1. Low Criticality AM Parts
- 2. F&DT and NDI Considerations
- 3. Knowledge transfer between machine makers and end users