Transcript National Materials Advisory Board

Ce
C
Standardized Materials
Databases
Cecil W. Schneider
CEC Technologies, P.C.
Marietta, Georgia USA
FAA/NASA Workshop on Key
Characteristics for Composite Material
Control
August 6-8, 2002
B025-01
Application of Commercial
Specifications for Composite
Materials Fabrication
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Composite Test Methods & Design
Data
Test Methods
• ASTM Test Methods
• SACMA Test Methods
• CMC Test Methods
Design Data
• MIL-HDBK-17
Used by all Lockheed Martin companies
Used on F-22
Used by CMC for standard testing to
develop materials screening database
Attempt to integrate CMC and SACMA test methods
made in 1995-96 by CMC, SACMA, ASTM D-30 & MILHDBK-17 did not complete due to lack of funding
Used where data exists
»
Limited high performance data
These specifications are existing and were developed
with active participation of users
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Composite Spec Development
• SAE Fiber Spec
AIA EWG
AMS 3960 fiber spec being developed
-- In 2nd ballot by SAE
-- Decision to finalize spec or discontinue at
next meeting
Coordination of cancelled DoD Standards and
Mil Spec’s hand off to SAE, ASTM and other
standards organizations
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Deterrents to Use of
Commercial Specifications
• Commercial specifications have not been available for most
materials to provide desired design properties
» Properties closely tied to structural analysis methodology
• Attempt by NASA, Boeing, McDonnell Douglas and Lockheed in
mid-80’s to develop tough epoxy spec
» Never applied to production parts
• Suppliers did not accept
• Attempt by Navy to develop tough epoxy spec
» Not applied to F-18E/F due to long list of exceptions required
Lack of suitable, approved commercial spec when program
is initiated will always result in use of company specs
Consensus processes is too long for any program
BUT…..
Without consensus, there is no buy-in!
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A Consensus Plan for National
Standards and Specifications
Standardization of Advanced Composite Materials
Developed by the
Ad Hoc Committee For Standardization of Advanced
Composite Materials (1992-3)
and incorporated into the
Aeronautics Materials and Manufacturing Technology
Standardization Plan (1994-5)
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Building Block Assessment for
Material/Structural Qualification
Laminate Performance
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Chemical & Physical
Properties
• HPLC
• DSC
• DMA
• …...
Constituent
Tests
Strength
Damage Tolerance
Joints
Process Properties
Cocure Issues
Microcracking
Thermal Cycling
Static/Fatigue
Environment
…...
Lamina
Tests
Laminate
Tests
Basic Properties
• Strength
• Stiffness
• Environment
Qualification
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Element
Subcomponent
Component
Tests
Full Scale
Loadings
Static/Fatigue
……
Full Scale
Tests
Critical Detail
Verification
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Boundary Conditions
Secondary Effects
Size Effects
Static/Fatigue
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Dependence of Test Methods
on Higher Level Standards
Material & Process
Specifications
Test
Methods
Analysis
Methods
Physical
Fiber Areal Weight
Resin Content
Volatile Content
Resin Flow
Gel Time
Glass Transition
Temperature
Mechanical
0 Degree Tension
0 Degree Compression
In-Plane Shear
Short Beam Shear
Open Hole Tension
Open Hole Compression
Bearing
Compression After Impact
Design Data
Lamina-based
Types
Lamina
Laminate
Interlaminar
Damage Tolerance
Laminate-based
Lamina-Laminate
Correlation
Interlaminar
Damage Tolerance
Improved Design
Allowables
Larger Database
Less Variability
Higher Confidence
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Design Allowable Data
• Design Allowables required to conduct detailed design
• Development of design allowables data time consuming and
expensive
— 6 to 24 months -- $500K to $3M
• Design allowables depend upon:
-- Material Specification
-- Process Specification
-- Test Method
-- Design & Quality Criteria
-- Analysis Methods
• Each program -- civil or military -- now develops program unique
documents and design allowables
– Design allowables for Hercules 3501-6 developed for:
V-22
F-18
> 25 Specs
A-6 Wing
Gulfstream III/IV
Most Of These Data Are Not Comparable
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Advanced Materials Design
Allowables Development
Raw
Materials
Material
Specificatio Process
n
Spec
Guidelines Guidelines
Criteria/Requirements
Test
Methods
Standardize
Pre-Competitive
Issues
Analysis
Methods
Design
Allowables
Product Design
Manufacture
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Material Selection Process for
Screening and Allowables
Competitive
Materials
Material
Suppliers
Select
Best
Screening Uniform
For
Tests
Data
Screening Materials
Tests
CMC Database -- Standard Tests - 66 Materials
Design Allowable Data Covers:
 Constituent Test
 Lamina Tests
 Laminate Tests
Product
Design
Screening
Data
Base
Design Allowable
Data Base
Select
For
Allowable
Test
Design
Allowable
Tests
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What is Needed?
• Coordination of overall effort
» Develop and direct integrated plan
• Focused industry and government support and
funding
» Manufacturers
» Material suppliers
» Certifying agencies
» Technical societies
» Mil-Handbook committees
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Specific Comments on Draft
Material and Process
Specifications
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Draft
Recommended Criteria and Guidelines for the
Development of a Material Specification for Carbon
Fiber/Epoxy Unidirectional Prepregs to be Used on
FAA Certified Aircraft
• Why restrict to FAA certified aircraft?
– Coordination with DoD would provide greater utility and use.
– Where is the inter-agency cooperation?
• Draft covers only unidirectional carbon/epoxy prepreg,
made with some unspecified process.
– There is little reference in draft to what material/process is
covered
– What type of cure process is applicable?
• “Industry Committee” for material specification is vague.
– What is this, how created and staffed/supported, etc.?
– Is this SAE Committee P?
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Draft Material Spec (Con’t)
• The document appears unnecessarily lengthy and
elaborate.
– Would be difficult to hand off to small companies and
expect them to understand/follow.
– Separate or simplified document should be created.
• Leave out justification and rationale
• The draft is very detailed in terms of setting
specific requirements that must be met.
– Yet the process specification is performance oriented -setting performance goals without all the ‘shall do’
– Recommend setting performance and quality standards - let material suppliers decide how to do it to meet the
standards
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Draft Material Spec (Con’t)
• “Incremental approach” towards design allowables may be
low cost …. BUT:
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Starts with screening database by supplier
How may end-users will take advantage of this?
Focused more on small startup companies?
Only B-Basis Allowables are of interest to FAA for certification
• Companies will not commit to aircraft design & production program
without plan for allowables development
• Allowables must be in hands of designer early in program to
reduce risk
– Should be plan for joint effort between many suppliers and endusers to develop allowables
• FAA-Directed procedure will not work
– Needs to be some form of consensus development
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Draft
Recommendations and Guidance for the
Development of a Process Specification for the
Fabrication of Carbon Fiber Reinforced Epoxy
Composite Structures
• First Four Sections somewhat vague in places as to intent:
– Section 2 Fabrication
• Focus is on panel fabrication -- Needs to lead to larger structures in
building block program
– Section 3 Producibility Demonstration Guidelines
• Not sure why Discriminator Panel is required?
• Need to clearly lay out path for Producibility Demonstration Articles
as part of Building Block program
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Draft - Process Spec (Con’t)
• Section 4 Fabricator Qualification Recommendations
– Needs to be clearer on requirements and path for End-Item
producer to qualify
• Including next level suppliers
• Section 5 Specification Recommendations
– Emphasis is on ‘Panels’
• Specification is for Structures
• Needs clarification on path for Building Block approach from
laminates and panels to full scale structures
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Overall Comments
• Draft specifications good start
• Need coordination with industry that will use them
– Sports and personal aviation
– General aviation
– Business aviation
– Regional aviation
– Large aircraft commercial
– Military aviation
• To be effective and used, there must be some form of
consensus
• Who pays the bill?
– Imposing requirements on Prepreg Suppliers did not work in
early 90’s -- when there were many
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A Century Of Progress
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