Meeting Called to Order  7: 05 pm Welcome Mike Mohaghegh

The Westin Peachtree Plaza

Atlanta,GA
AIAA Structures TC Meeting Minutes

Monday April 3, 2000

7:00 to 10:00 PM
Meeting Called to Order  7:05 pm
Welcome Mike Mohaghegh

Larry Pinson addressed the TC:

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  Charley Saff will take over position of director of structures/design
  
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  Enjoyed himself during his years with the committee
  

Welcome by Mike Mohaghegh

*Not a complete listing, ~90%

A focus for future: enhanced safety

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  Structures problems 4% of safety problems in service. Maintenance 14%. All others balance.
  
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  As flying hours increase, accidents will increase. Hope to reduce accident rate significantly
  
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  Many airplanes flying beyond design lives. This is a concern.
  
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  Clarified design criteria.
  
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  Boeing recently finished a book: Structures Design Principals (includes design philosophy, lessons learned, requirements, etc.). This book is internal to Boeing.
  
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  Doing more fatigue testing, especially on the 777 (3 design service objectives, +20,000 pressure cycles).
  
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  Maintenance work is being enhanced to improve safety.
  
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  747 corrosion improvements slide.
  
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  MSD (multi-site damage), MED (multi-element damage) - much research in these areas.
  
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  Once MSD begins, residual strength decreases rapidly
  

Other future focus areas: reduced cycle time, reduced cost, improved quality, increased customer satisfaction.

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  Lean and efficient design - much work in this area.
  
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  Trying to shrink cycle times and costs of aircraft development.
  
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  Knowledge based engineering, used it on 777, 737-NG. Next airplane to be primarily designed by this system. Allows more efficiency.
  

TC comments/discussion…

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  Raouf Ridha - is there a conflict between knowledge based and rules based? Mike Mohaghegh had equated them on overhead. Raouf Ridha disagrees somewhat - does rules based take out the need for knowledge?
  
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  Jayanth Kudva - Do you capture knowledge of retirees? Structures Design Principals book mentioned above is meant to help capture this knowledge. Try to capture this knowledge. Even failure case histories are in the Boeing books. Lessons learned. Good designs and bad designs are both shown. Started this when SST went wrong. (Answers from Mike Mohaghegh and Ramesh Shah)
  
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  Jayanth Kudva has found folks are not really willing to talk about their mistakes.
  
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  Mike Mohaghegh willing to share the general approach to on these books.
  

Mike Mohaghegh resumes:

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  Examples of some things they are working on: 737 wing rib with high speed machining, fuselage frames now one piece frames
  
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  Cost-Benefit analysis - Net present value (NPV) probability of NPV outcome - every project reviewed on these terms
  

Mark Johnson is of Phantom Works, Advanced Military Aircraft Division.

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  Background information on phantom works.
  
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  Integrated design loads process: modeling tools, critical maneuvering loads, optimization, benefits that result…
  
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  Value, performance, cost all tied together in design philosophy.
  
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  Four pillars of cost effectiveness: lethality, supportability, survivability, affordability
  

New operating paradigms:

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  Teaming (SNECMA, P&W, Allison & Rolls, Allied Signal)
  
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  Search for wonder-metal abated
  
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  Productivity job #1
  

Major Industry Problems:

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  HCF, combined HCF/LCF (high and low cycle fatigue)
  
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  Edge of contact (many places in engines have contact load transfer)
  
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  AIA rotor integrity committee
  
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  Aging engines
  
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  Maintenance - not all maintenance is good maintenance
  
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  Experienced engineers
  

Linked Model Environment (LME):

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  Moving toward LME - all the same geometry capable of quick iterations. Need a geometry database storing all design, stress, etc. data. Current process is greatly crossed between disciplines…new process is cleaner (in theory). New process has need for less people. Expressed concerns about the apparent lack of checks and balances that have worked so well in the past.
  

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  Integration is big
  
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  Fully integrated structural life prediction system - looking to add residual stress to FEA, improved constitutive models, fully integrated system trying for more accuracy.
  
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  AIA rotor integrity committee…result will be a damage tolerance code
  
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  FAA Vision to have an industry standard approach to damage tolerance
  
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  Another program: HCF S&T Program - looking to eliminate HCF failures in engines
  
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  HCF basically could be stated as high frequency fatigue. Talking 10⁶, 10⁹.
  
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  Looking to something more than Goodman type approach to HCF
  
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  FOD with respect to HCF. Went out and measured FOD experienced in the field. Developed a test technique with GE to evaluate FOD type damage in lab.
  
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  Mike Mohaghegh - What is your damage tolerance criteria? For HCF, can’t tolerate anything growing. For LCF design, assume a flaw just below detectable limit.
  
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  Looking at laser shot peening (LSP) to improve damage tolerance of blade leading edges. Very promising but expensive.
  
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  F119 engine being used to validate HCF damage tolerant design technique. Will run a damaged blade in test and validate their predictions.
  

Focus on space structures technology.

Launch vehicles: manned vehicles (reusable) and expendable/unmanned

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  Volume is a concern. Weight is a concern.
  
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  Satellite loads:
  
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  Launch loads (acoustic, separation, thrust, wind, drag, vibration, thermal, shock)
  
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  On-orbit loads (operational, station keeping, thermal transient, astronaut)
  
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  Space structures:
  
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  Material requirements: high strength, light weight, high stiffness, low CTE, low outgassing, high tolerance to space environment
  
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  Design requirements: strength, weight, dimensional stability, thermal distortion, produceability, accessibility, testability
  
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  Commonly used designs: beam/truss, thin plate/shell, honeycomb panel
  
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  Common materials: aluminum, graphite-epoxy, titanium
  
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  Shows typical spacecraft structures.
  
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  Zero G environment is unique to space structure design – have structures that would collapse if deployed on earth. Cannot do testing on earth. Verification of structures is a challenge.
  

Structures Research at NASA Langley Research Center (LaRC)

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  Going through a period of change at NASA. Recently lost HSCT and subsonic programs.
  
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  Presents flow chart showing current program offices.
  
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  LaRC Structures and Materials Center of Excellence. Core work: airframe systems (primary structures for subsonic and high-speed a/c), Advanced space transportation (primary structures, cryo-tanks, metallic thermal protection for reusable launch vehicles), spacecraft technology (cross-cutting materials and structure technology for future mission needs of space science, earth science, and HEDS Enterprises (human exploration of space)).
  
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  Structures and Materials Competency has 7 branches (advanced materials, aeroelasticity, analysis and computational methods, mechanics and durability, metals and thermal structures, NDE Sciences, structural dynamics)
  
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  Biggest change in last 6 months - becoming engaged in reusable launch vehicles (RLV). 1^st generation is space shuttle - out of service 2012-2015. 2010: 2^nd generation (focus on transportation only, ISS orbital scientific platform, 10x cheaper, 10x safer), 2025: 3^rd generation (new markets enabled, multiple platforms/destinations, 100x cheaper, 100x safer - this safety would be on par with existing aircraft), 2040: 4^th generation (routine passenger space travel, 1000x cheaper, 1000x safer) [10x, 100x, etc. in relation to 1^st generation]
  
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  In the process of planning 2^nd and 3^rd generation programs.
  
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  Members note these goals are ambitious. These goals were presented to OMB and are the current plan. Plans still very much being formed at this time.
  
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  Airframe Technology Project (w/in 3^rd generation concept). Objective: Looking to develop airframe tools for ultra-rapid variable fidelity modeling, analysis, and design. Strong emphasis on advanced cryogenic tanks, hot structures, thermal protection materials and systems.
  
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  Four elements: (1) Integrated airframe design (2) integrated thermal structures and materials (3) thermal protection systems, (4) aero/aerothermal enhancement
  
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  In spacecraft, large emphasis on solar sails, inflatables, large apertures.
  
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  Inflatable structures technology: still working on this maturing technology
  
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  Deployable reflector technology: working to understand how to make tight tolerance arrays upon deployment, how to control thermal gradients and deformations.
  
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  Aerospace Vehicle Systems Technology: advanced subsonic transport program is gone. Looking for synergy with advanced space transportation group.
  
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  Still active in AVST - Inherently Reliable Systems program. NDE, life prediction, accelerated tests, uncertainties, etc.
  
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  SLMFST (super lightweight multi-functioning systems) - objectives: innovative new material, multi-function structural concepts, integrated design methodology
  
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  AGATE - looking to reenergize GA airframe industry. Drawing to a close. Will be replaced by Small Aircraft Transportation Systems. Looking to take advantage of smaller airports which are not being fully utilized.
  
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  Hyper X (pegasus boost, stage separation, scramjet engine operation)
  
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  Mechanics and Durability Branch:
  
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  Structural integrity and residual strength methodologies for composite structures
  
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  Structural integrity and residual strength methodologies for metallic structures
  
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  Structures technologies for advanced aerospace vehicles concepts (pressurizing noncircular shells, joined wings, etc.)
  
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  Analytical and Computational Methods Branch:
  
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  NextGRADE
  
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  Refractory Composites
  
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  High temperature RLV structure concept
  
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  Structural Dynamics Branch:
  
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  Airframe Crashworthiness Assurance
  
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  Innovative Composite Fuselage Concept for Improved Crashworthiness (energy absorbing sub floors, Mars sample return vehicle)
  
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  NDE Branch:
  
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  Develop instruments and devices to allow field inspection for cracks and corrosion, etc.
  
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  Vehicle health monitoring systems (X33 Fiber Optic Distributed Strain System)
  

Paul Tan works in aircraft safety division.

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  NDI: Objective - to assure structural integrity by: (1) enhancing knowledge base associated with degradation of structures due to fatigue and crack growth, (2) providing an increased understanding of fatigue degradation in general and the impact of MSD and MED.
  
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  WFD Evaluation: to develop a procedure for predicting MSD initiation and residual strength of a structure containing MSD.
  
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  Crack Initiation Analysis: FASTRAN III, AGARD report
  
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  EIFS Study: equivalent initial flaw size - working on developing an EIFS for commercial OEM
  
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  Small Crack Growth Testing - using FASTRAN
  
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  Work on MSD flat panel and curved panel and then move to pressure bulkhead.
  
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  After developing analysis tools, hoping to do a tear-down and inspection of an L-1011. Planning on looking at 727 as well.
  
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  Premium Quality Airframe Castings (unitized structures) - looking at damage tolerance of these structures.
  
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  Full-scale aircraft structural test evaluation and research (FASTER)
  
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  RAPIDC - develop an automated static strength and damage tolerance analysis tool to assess common metallic repairs and antenna installations (for commuter industry)
  
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  HUMS (health usage and monitoring system)
  
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  Rotorcraft damage tolerance roadmap (RCDT)
  

With AIAA.

Re: conference administration system

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  Will be used to streamline data to useful end products
  
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  Has been beta tested and was found to be good
  
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  Have made some improvements, planning 2000 release of version 1.0.
  
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  All future meetings will be produced using this program.
  
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  All authors will be able to access system using same URL. Similar sites will be available to chairman, etc.
  
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  Abstracts can be submitted electronically. Also accepted and revised electronically.
  
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  Tracking and rating can be done using this system. Sessions can be set up, rooms chosen, etc.
  
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  Authors can submit complete manuscripts electronically.
  
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  Allows for system archiving.
  
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  Conferences will be better organized.
  
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  Future: increasing reliance of system, expand using these basic data structures.
  
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  Official Kickoff - 15 June 2000.
  
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  Demonstrations will be done 4/4/00 during SDM. Demonstrations also at other conferences which will follow during the year.
  
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  System accepts Word files, for instance, so can use color. Translates into .pdf files. Will look into animations for future. Not currently accepting animations.
  
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  Would prefer to take .pdf files. Can convert other file types to .pdf.
  
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  Do not take postscript files.
  

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  We need to recommend people to represent our committee. It is the Structures TC turn to provide people for technical chair and general chair.
  
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  Both Ben Thacker and Aditi Chattopadhyay have volunteered to be the technical chair.
  
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  Mike Mohaghegh has said that if no one else wants to be general chair that he will make that commitment.
  
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  No one else stated interest in being the general chair or technical chair.
  
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  Mike Mohaghegh will be the general chair. No disagreements by the committee.
  
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  The idea of co-technical chair was discussed. It was decided that we cannot have co-technical chairs.
  
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  By vote, Ben Thacker was chosen to represent the committee as technical chair.
  

The Westin Peachtree Plaza

Atlanta,GA
AIAA Structures TC Meeting Minutes

Wednesday April 5, 2000

12:00 to 2:00 PM
Lunch Begins 12:00 pm

Meeting Begins 12:27 pm
Attendance:

Mohammad Aminpour	Mary Mahler for J. Kudva	Fuh-Gwo Yuan
Prabhat Hajela	Charles Saff	Harn Chen
Richard McKnight	S. Nagendra	Tony Waas
Raouf Ridha	Mike Nemeth	Harry Hilton
Johann Arbocz	Bruce Willis	Alex Bogdanovich
Jim Starnes	Mark Johnson	Karl Drutowski
Charles Shih	Paul Tan	D.B. Paul
Chris Clay	Lori Scheufele

American Society for Composites Report Chris Chamis

Note: Due to other commitments of Chris Chamis, this report was presented at the beginning of the meeting:

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  Annual meeting at Texas A&M in September.
  
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  ~100 papers.
  
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  Researchers award will be presented for students.
  
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  Fellowship award will be presented for professors.
  
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  A current issue for ASC: Will society become large enough to provide insurance? In discussion with insurance companies.
  
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  Civil engineers getting more involved in composites.
  

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  Mike Mohaghegh thanked the presenters on Monday, 4/3/2000. Has received good feedback from members of committee on those presentations.
  
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  Presenters should give copies of their material to Mike Mohaghegh in order to be compiled and distributed.
  
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  Recognize 3 of those who made special efforts for this conference -- presented by Raouf Ridha:
  

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  Be sure to let the awards committee know of people who you think should be recognized for their efforts
  

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  Many thanks to Don Paul for his efforts on these sessions.
  
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  23 papers submitted – 11 papers selected.
  

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  Several sessions this year.
  
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  Future thrust areas for sessions: affordable composite structures, heterogeneous structures and functionally graded materials (do not think this is a conflict with smart structures), damage modeling and evaluation in composites
  
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  Anyone interested in special sessions on these areas please e-mail Aditi Chattopadhyay
  

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  Mike Mohaghegh: It might be worthwhile to have a panel session on affordability. Session on cost modeling may also be worthwhile
  
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  Committee: Concerned companies won’t want to talk about their cost modeling.
  
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  Don Paul: It is possible to discuss cost modeling without giving away too much information on the costs incurred by individual companies in their work. This topic is very important and drives structures design today.
  
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  Committee: Consensus seems to be that cost modeling is a very important topic - we should pursue this as a panel discussion or session. It should be kept broad in scope for this first attempt - all fields.
  
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  Don Paul: Definitely could do a session, but panel discussion might be most productive in helping attendees of SDM - others agree
  
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  Committee: Concerning Aditi Chattopadhyay’s suggestions for new sessions, no disagreement (see above)
  
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  Richard McKnight: Need the agencies sponsoring research in these areas to encourage presentation of papers.
  
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  Chris Clay: Recommendation for session on extreme environment structures (temperature, acoustic, and flight loads combined). Chris Clay designated by Mike Mohaghegh to lead the effort on this special session.
  
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  Committee: Innovative structures session could have a deployable antenna structures session (Sergio Pellegrino will take the lead.)
  
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  Information on special sessions will have to be completed for the technical chair by July time frame -- Abstracts will be needed by August.
  

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  Communicate any ideas to Mike Mohaghegh or David Jensen.
  
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  Looking at role of organizations outside AIAA such as MDO, etc. to decide if they should become part of the process.
  
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  Benchmarked SDM against ASME and Aging Aircraft conference – felt AIAA doing a good job of running SDM but there is room for improvement: quicker CD, electronic information system for organization, awards, overall planning of conference.
  
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  Should current forums be incorporated into the structure of SDM so can have forums on different new technologies.
  
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  Will be talking about 2002 and 2003 SDM locations tonight.
  
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  No plan in next couple of years to have electronic presentation format. Currently the problem is the hotels, who are not up to speed on this presentation technique. The penalty for going to electronic presentations right now is just too great.
  

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  Technical representative for next year’s SDM.
  
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  Deadlines: 4/2000 Call for papers
  

9/27/00 Student paper abstracts due

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  Would like to change process such that papers are reviewed prior to fall TC meeting. This would allow more time to deal with other issues at the fall meeting.
  
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  New electronic submittal system could make this possible, although the system is not flaw free. Keep hard copies of what you work with.
  
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  New electronic process is agreeable.
  
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  Fall meeting needs to be before 9/29/00. Mid-September is best time frame. 15^th of September is the probable date at this time. Possible locations: Colorado Springs or RPI (Albany, NY)
  

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  Would like to have article ready for committee meeting in Sept.
  
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  Submit your topics to Harry Hilton by 9/1/00.
  
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  Suggested Topics:
  
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  Aging aircraft
  
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  Computational issues
  
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  Smart and damping materials
  
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  Reliability, probabilistic methods
  
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  Long distance education
  
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  Contact Harry Hilton with ideas or questions.
  

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  Course on stability covering issues not typically covered at universities.
  
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  Attendance was not that good - only 2 people signed up for the course and it had to be canceled.
  
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  Needed a minimum of 6 people for the course to proceed.
  

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  Mike Mohaghegh suggested a course on aircraft structures (Mike Mohaghegh could teach this course).
  
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  Ben Thacker suggested a course on reliability based structural design.
  
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  Need to present a course that is of interest but not covered in university courses.
  
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  Propose courses to the education committee. Allow them to help you develop the course. Have a target audience in mind.
  
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  Should consider and sell the fact that we have technical sessions at SDM dealing with issues offered in the courses.
  
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  Should target all meetings, not just SDM.
  

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  This issue to be discussed more at the fall meeting.
  
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  Jayanth Kudva will be next year’s chairman. He will head the membership activities until then.
  
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  The committee needs help with webmaster position.
  
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  The committee needs a subcommittee chair for extreme environment structures.
  

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  Structural Dynamics is putting together materials for a video for high school kids to get them interested in structural dynamics.
  
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  Thinking of an interactive CD-rom and may broaden scope to include structures in general.
  
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  May be coming to this TC for ideas in the future.
  
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  Will be giving responsibility of student paper award back to SDM committee.
  

What worked, what didn’t? What can we do better as a TC?

Reports from leading organizations to TC Need to get subcommittees together

Divide technical discussion to both meetings
Suggestions

Subcommittees should meet at SDM (more people will likely by in attendance).

Subcommittees should teleconference during year.

Have a room available all week for subcommittee meetings during the SDM.

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  Recruited people for committee to actively participate in committee
  
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  Listed members of the subcommittee.
  
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  Established guidelines for subcommittee. These were shared with the TC last August.
  
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  Previous nomination for Honorary Fellow was submitted with updated write-ups and recommendations.
  
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  Previous nomination for Fellow was continued for a second time.
  
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  An upgrade to Senior Member was completed and submitted.
  
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  On behalf of the TC, two subcommittee members participated in selecting the SDM award for this year. Our representatives had concerns about how this award was handled. Reservations were conveyed to the SDM.
  
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  Three citations were prepared for contributions pertaining to the present SDM conference.
  
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  A listing of current AIAA members with a “structures” affiliation was sent to each awards subcommittee member so that they might select nominees for membership upgrades.