The committee received important perspectives in a number of areas from persons at universities, corporations, and government agencies. These persons are listed here along with some of their key points.
1. James Ashton, ''Life-Cycle Engineering of Structural Components," Schlumberger Well Services, July 17, 1986
There is a clear distinction between design and manufacturing. The "ideal" design solution is a continuous, nonjointed structure that analysis shows has requisite load and stress supporting capability. However, continuous structures cannot be manufactured for several reasons—size, complexity, etc. Joints and attachments are difficult to analyze, test, manufacture, and maintain but are absolutely necessary from a supportability viewpoint. Cost reductions are most easily effected early in the design phase of a system (versus later in the purchase phase). The major life-cycle costs drivers are:
Acquisition costs 28 percent (design ~ 20 percent)
Operation costs 12 percent
Logistic support 60 percent (repair labor costs ~ 40 percent, spares replenishment ~ 10 percent)
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components APPENDIX C PRESENTATIONS TO THE COMMITTEE The committee received important perspectives in a number of areas from persons at universities, corporations, and government agencies. These persons are listed here along with some of their key points. 1. James Ashton, ''Life-Cycle Engineering of Structural Components," Schlumberger Well Services, July 17, 1986 There is a clear distinction between design and manufacturing. The "ideal" design solution is a continuous, nonjointed structure that analysis shows has requisite load and stress supporting capability. However, continuous structures cannot be manufactured for several reasons—size, complexity, etc. Joints and attachments are difficult to analyze, test, manufacture, and maintain but are absolutely necessary from a supportability viewpoint. Cost reductions are most easily effected early in the design phase of a system (versus later in the purchase phase). The major life-cycle costs drivers are: Acquisition costs 28 percent (design ~ 20 percent) Operation costs 12 percent Logistic support 60 percent (repair labor costs ~ 40 percent, spares replenishment ~ 10 percent)
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components 2. L. A. Belady, "Software Life-Cycle Engineering," Micro Electronics and Computer Technology Corp., June 20, 1986 Life-cycle engineering of very large software systems (developed by more than one person per organization) is now becoming appreciated, reflecting the inevitability of software evolution—i.e., repairing (patching) as well as enhancement—due to new use requirements or advancing technology (new devices or codes). Most of the cost of software is devoted to maintenance activities. There appear to be parallels between ULCE of software and of structural components. Complex software is developed in modules. Software engineering transforms fuzzy requirements (obtained in dialogue between user and software writer) into exact programs. At an intermediate stage, software requirements become formalized, and thereafter effort is focused on writing the programs. The bulk of software problems arise from incompatibility at interfaces between different modules. As modifications are made, one module may change in a different way than others. But compatibility among the modules is still essential. The time period from initial requirements to first modification may be a few months or years; this time increases with subsequent modifications as systems become more rigid. For different customers, the configuration of the software may be different. 3. Thomas Bennett, "ULCE Supportability Aircraft Structure," General Dynamics, July 17, 1986 Supportability requirements and consideration are different under peacetime and wartime conditions. The continuing goal for advanced military aircraft is to reduce the percentage of the total weight taken up by the structure. A key observation regarding supportability of aircraft is that the trend of maintenance man-hours per flight-hour is increasing substantially for the structural systems but decreasing for most other subsystems. However, the subsystems may fail in ways other than predicted, so that lack of capability to repair (e.g., not having a spare available) may cause greater loss of availability than repair time. The three top causes of loss of structural durability are cracking, corrosion, and maintenance-induced damage. 4. J. Coleman and Alan Herner, United States Air Force (USAF) Human Resources Laboratory, June 19, 1986 The ongoing Maintenance and Logistics in Computer-Aided Design program at the Air Force Human Resources Laboratory involves all three services as well as the Institute for Defense Analyses (IDA) and the National Security Industrial Association (NSIA). In the present design process, logistics (supportability) issues such as reliability and maintainability are normally addressed after design features for cost and performance are frozen. The objective of MLCAD is that supportability issues be addressed within the active design window by using computer-aided techniques. The enabling technologies rely on computer techniques, system networking, and integration. A survey by NSIA showed that cost of modification once manufacturing has started can be as much as a thousand times more than eliminating the problem in the design phase. Two examples of successful implementation of the MLCAD principles were given: (a) redesign of the Cruise Missile Launch System's generator to improve its reliability as well as access for maintenance and (b) simulation of the maintenance task required for the F-15 while it is in a shelter, to flag problems during that process.
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components 5. Michael Dubberly, "Structural Life Management of Navy Aircraft," Naval Air Systems Command, September 29, 1986 For the Navy, the design point is the "severe usage spectrum," not the Air Force's criterion of "average use spectrum." This difference may lead to different weight requirements—e.g., for the F-18 fighter, the maximum fatigue load versus average requires an additional 100 pounds (a few percent of airframe weight). Note that additional weight and conservative design are key for the airframe (used for the life of the plane) but not for components that are changed frequently. For graphite fiber-reinforced composites, at present, it is not possible to transfer laboratory test data to fleet performance as is done with metals because the lab test behavior of the composite is more environment-sensitive than that for metals. The composites are dependent on process controls during manufacturing, not post-manufacturing inspection, and a guaranteed material toughness is needed. The design approach for fleet service allows no failures (cracks) in the design lifetime and requires that complete traceability of each plane's operations history be maintained. A case history for the wing of the A-6 aircraft indicated that a block test program showed the design to be conservative, yet a flight-by-flight test (all components on one plane tested) showed that the design was nonconservative. 6. Stephen Finger, "Turbine Disk Case History," Pratt & Whitney, July 17, 1986 Design considerations for the F-100 turbine engine were reviewed. The service environment is difficult to measure, and it is important to monitor centrifugal, thermal gas, bending, and vibrating stresses. Indeed, comparison of the qualification test with the predicted design mix and with the actual operation shows substantial differences—principally in cyclic power requirements (hence lowcycle fatigue properties). The Pratt & Whitney design tools support group and review process were also discussed. Design criteria and verification are a composite of "lessons learned" based on engine requirements, past experience, and military specifications. Changes in configuration of a component and its resulting producibility—e.g., powder processing (gatorizing)—are checked with various groups, including engineering, product support, and the customer (the USAF—it provides data bases). The payoff of this interactive design approach has been that 97 percent of repairs are accomplished at base level, leading to rapid repairs. Two mechanisms to identify incipient problems are accelerated mission tests and "lead-the-fleet" pacers. 7. Dan Good, "Army Perspective on ULCE," U.S. Army Aviation Systems Command, June 19, 1986 The Army has the "Flight Safety Parts Surveillance Program" to ensure that design requirements are being met in use operation. Possible causes of a helicopter fatigue failure were discussed. These include (a) failure of related parts that indicated use outside the design spectrum; (b) critical part without fail-safe design; (c) the material used was notch-sensitive; (d) process controls were not adequate; (e) manufacturing changes were made without proper design considerations (feedback loop); and (f) analysis shortcomings. The ULCE approach might have identified the problem. Certainly, an information system could have been useful in gathering facts. But, even with a data base, a framework would be needed to use the information in a system-accept-or-reject capacity.
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components 8. John Mayer, "Design, Manufacturing, and Computer Engineering Division Programs at NSF," National Science Foundation, June 20, 1986 Programs in the Design, Manufacturing, and Computer Engineering Division were described. For design and manufacture there are analysis methods available. A menu may be needed more than a model. 9. J. R. Meeker, "ULCE Promises a Return on Investment," U.S. Air Force, June 19, 1986 ULCE is one of two Forecast II initiatives where the Air Force is investing in its future base technology; the other is quality in manufacture. ULCE is needed to address the following: (a) weapon systems are being planned for 10-to 50-year lifetimes—i.e., the Air Force cannot afford to change its fleet; (b) new systems frequently need major modifications within the first year because the original design does not perform satisfactorily; (c) application of new technology is slow; and (d) logistics is done inefficiently. The Air Force strategy is to develop a government-industry consortium, advocate CAD, CAM, and CAS, integrate these, and use ULCE in applications by the year 2000. ULCE near-term efforts are focusing on developing design tools and models for CAS to provide for interaction between CAS, CAD, and CAM tools and models and to integrate the design-assisting software into a decision-support system within the design environment. Long-term efforts include concentrating on the development of a technology base for the next generation of design systems to include cradle-to-grave management, reducing design to manufacturing lead time, reducing prototype requirements, and providing supportable design. 10. J. Stanley Mosier, "Case Study of a Metallic Gas Turbine Disk," G.E. Aircraft Engines, March 4, 1987 The subject case study of a metallic gas turbine disk (included in report as Appendix A), was conducted by the author in support of the committee's work to compare the results of a recent actual hardware design experience with generic ULCE needs and concerns that had been established by the committee. The high pressure turbine disk of the F110 augmented turbo fan engine was selected as a technically appropriate and timely example. As a product of this study, a checklist format relating life cycle engineering considerations to the functional engineering areas of materials, design, manufacturing assembly and test, and product support were developed. In addition, a list of specific life cycle engineering needs and concerns defined by the F110 HPTD design experience evolved. A comparison of the case study items identified, associated each with at least one of four critical issues defined by the committee. Through these comparisons this case study supported the validity and completeness of the generic critical issues developed by the committee. 11. D. Mulville, "Systems Effectiveness Definitions," NAVAIR (now with NASA) Systems effectiveness definitions were given: Operational Dependability—the probability that the equipment, if up and ready at the beginning of a mission, is able to successfully complete the mission. Any in-flight anomaly (i.e., material failure, operability deficiency, or performance deficiency) that may result in a mission loss is an operational dependability problem. Operational Capability—the ability of the equipment to perform its intended mission. Operational capability problems degrade mission effectiveness but do not affect mission
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components completion. Normally these problems manifest themselves in the ability of the equipment to meet original specification performance. Operational Availability—the probability that the equipment is up and ready to perform as intended. Operational availability problems are normally the result of problems in equipment design, integrated logistic support, or both. Three additional definitions pertain: Reliability—the probability that an item can perform its intended function for a specified interval under stated conditions. Mean time between failure (MTBF) and component removals are indicators of equipment reliability. Maintainability—the ability to restore a system to an operational condition under specified logistics conditions. Mean time to repair (MTTR) is an indicator of the equipment's inherent maintainability. Supportability (Logistic Support)—the ability to satisfy the material, logistics, and mission requirements to restore the operation of failed or damaged equipment or components. An indicator of logistic support is mean downtime per failure (MDT). MDT is a function of two items: (1) the time necessary to repair a failed system at the organizational level and (2) the additional delay caused by the logistic support for the equipment (i.e., the time required to obtain a replacement part or material from the supply system and the time necessary to repair failed systems at the intermediate or depot level). Aircraft Survivability—the capability of an aircraft to avoid and/or withstand a hostile environment: Survivability = Ps = 1-[Vulnerability] [Susceptibility] Aircraft Vulnerability—the inability of an aircraft to withstand the damage caused by the hostile environment: Vulnerability = Pk/h (Probability of kill given a hit) Aircraft Susceptibility—the ability of an aircraft to avoid being damaged by the hostile environment: Susceptibility = Ph (Probability of hit) Aircraft Survivability Enhancement—any particular characteristic of the aircraft, specific piece of equipment, design technique, armament, or tactic that reduces either the susceptibility or the vulnerability of the aircraft and has the potential of increasing the survivability of the aircraft. 12. W. Reimann. "Unified Life-Cycle Engineering," AFWAL/MLTC, June 19, 1986 ULCE is ranked in the top ten items in Air Force Forecast 2000 and is viewed as the technical route to improved logistics support. The trend of Air Force programs in ULCE is toward the increasingly ambitious scope of integrating information for design and manufacturing operations. Enabling technologies above and on the shop floor are considered.
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components ULCE is viewed as the integration of three activities—CAD, CAM, and CAS/CAM. By the time 5 percent of the funds are actually spent, 85 percent has been committed. Hence there is great leverage in bringing more information into the design stage. Current programs on CAS reveal areas in components that cannot be inspected—i.e., probed with NDE methods. The question arises whether integrating CAD and CAM with CAS could yield components with better inspectability even if other performance factors are compromised—e.g., increased weight. The development of ULCE requires a common data base. In contrast, today's Air Force (and its contractors) has separate data bases; for example, the Air Force Logistics Command found more than 660 data bases throughout the Air Force network. The problem arises in how to transmit data among different data bases. The Air Force wants to have a data representation protocol compatibility with different computer systems. Prior Air Force programs—ICAM, IDEF, and CIM—emphasized ''above the shop floor" activities; programs include product definition data interface (PDDI) and geometrical modeling applications programs (GMAP). The ultimate goal is to develop a part definition standard. 13. Albert Russell, "Life-Cycle Enhancement of Electronic Systems," University of Massachusetts, June 20, 1986 In small electronic devices, 70 percent of the costs is associated with assembly. Three questions are asked regarding need for mechanical assembly of parts: Is there relative motion between the part and adjacent ones, must it be made of different material, and does it play an integral role in accessibility to other parts? For mechanical assembly, a design efficiency can be computed. For printed circuit boards (PCBs), rules for defining whether a part can be eliminated have not (and perhaps cannot) be formulated. Proper assembly probably cannot be verified until the entire PCB has been fabricated. 14. Ken Taylor, "Life-Cycle Engineering of the F-16 Horizontal Stabilizer," General Dynamics, July 17, 1986 The horizontal stabilizer for the F-16 was modified to respond to three "needs": (a) improve pitch control at low-airspeed and high angle of attack situation, (b) shorten take-off distance, and (c) shorten landing roll. The first need was provided by pilots on the performance of the aircraft in dogfights. The modification was to fabricate the stabilizer as a built-up structure rather than a honeycomb bonded one. Lessons learned for design, manufacture, and product support maintainability were enumerated. In all cases, more information would have been helpful, but it is not clear that this could have been specified in advance. 15. Richard Wright, "National Engineering Laboratory Programs," National Institute of Standards and Technology (NIST), June 20, 1986 ULCE-related programs at the National Engineering Laboratory were reviewed with emphasis on the Center for Building Technology. Areas of interest are advanced measurement techniques, performance modeling and prediction, automation of building operating systems, and information interface technologies. Throughout these areas, the concern was raised regarding interfacing information across different communities and through the life cycle of the building. Also discussed was initial graphics exchange specifications (IGES). For the "construction" industry, the major technique for achieving reliability is fail-safe design—e.g., inelastic deformation of floors before failure. The time period from initial concept to completed building is 3 years with an excellent building team and 7 years average.
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components 16. Brief program reviews were also given on Navy and NASA programs, as follows: Charles Zanis and Louis Sloter, "ULCE Navy Interests," Naval Sea Systems Command, June 19, 1986 Richard Weinstein, "NASA Life-Cycle Engineering Areas of Interest," NASA, June 19, 1986
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