Glenn (Formerly Lewis) Research Center

Glenn is the primary Center for research on all aspects of aircraft and spacecraft propulsion, including engine-related structures. The struc­tures area has typically consisted of approximately 50 researchers (not counting materials).[866] Structures research topics include: structures sub­jected to thermal loading, dynamic loading, and cyclic loading; spinning structures; coupled thermo-fluid-structural problems; structures with local plasticity and time-varying properties; probabilistic methods and reliability; analysis of practically every part of a turbine engine; Space Shuttle Main Engine (SSME) components; propeller and propfan flut­ter; failed blade containment analysis; and bird impact analysis. Some of the impact analysis research has been collaborative with Marshall Space Flight Center, which was interested in meteor and space debris impact effects on spacecraft.[867] Glenn has also collaborated extensively with Langley. In 1987, there was a joint Lewis-Langley Workshop on Computational Structural Mechanics (CSM) "to encourage a cooper­ative Langley-Lewis CSM program in which Lewis concentrates on engine structures applications, Langley concentrates on airframe and space structures applications, and all participants share technology of mutual interest.”[868]

Glenn has been involved in NASTRAN improvements since NASTRAN was introduced in 1970 and hosted the sixth NASTRAN Users’ Colloquium. Many of the projects at Glenn built supplemental capabil­ity for NASTRAN to handle the unique problems of propulsion system structural analysis: "The NASA Lewis Research Center has sponsored the development of a number of related analytical/computational capa­bilities for the finite element analysis program, NASTRAN. This devel­opment is based on a unified approach to representing and integrating the structural, aerodynamic, and aeroelastic aspects of the static and dynamic stability and response problems of turbomachines.”[869]

The aircraft and spacecraft engine industries are naturally the pri­mary customers of Glenn technology. However, no attempt is made here to document this technology transfer in detail. Other essays in this vol­ume address advances in propulsion technology and high-temperature materials. Instead, attention is given here to those projects at Glenn that have advanced the general state of the art in computational structures methods and that have found other applications in addition to aero­space propulsion. These include SPAR, NESSUS, SCARE/CARE (and derivatives), ICAN, and MAC.

SPAR was a finite-element structural analysis system developed ini­tially at NASA Lewis in the early 1970s and upgraded extensively through the 1980s. SPAR was less powerful than NASTRAN but relatively inter­active and easy to use for tasks involving iterative design and analysis. Chrysler Corporation used SPAR for designing body panels, starting in the 1980s.[870] NASA Langley has made improvements to SPAR and has used it for many projects, including structural optimization, in conjunc­tion with the Ames CONMIN program.[871] SPAR evolved into the EAL pro­gram, which was used for the structural portion of structural-optical analyses at Marshall.[872] Dryden Flight Research Center has used SPAR for Space Shuttle reentry thermal modeling.

Numerical Evaluation of Stochastic Structures under Stress (NESSUS) was the product of a Probabilistic Structural Analysis Methods (PSAM) project initiated in 1984 for probabilistic structural analysis of Shuttle and future spacecraft propulsion system components. The prime contractor was Southwest Research Institute (SwRI). NESSUS was designed for solving problems in which the loads, boundary con­ditions, and/or the material properties involved are best described by statistical distributions of values, rather than by deterministic (known, single) values. PSAM officially completed in 1995 with the delivery of NESSUS Version 6.2. SwRI was awarded another contract in 2002 for enhancements to NESSUS, leading to the release of Version 8.2 to NASA in December 2004 and commercially in 2005. Los Alamos National Laboratory has used NESSUS for weapon-reliability analysis under its Stockpile Stewardship program. Other applications included auto­motive collision analysis and prediction of the probability of spinal injuries during aircraft ejections, carrier landings, or emergency water landings. NESSUS is used in teaching and research at the University of Texas at San Antonio.[873] In some applications, NESSUS is cou­pled with commercially available deterministic codes offering greater structural analysis capability, with NESSUS providing the statistically derived inputs.[874]

Ceramics Analysis and Reliability Evaluation of Structures (SCARE/ CARES) was introduced as SCARE in 1985 and later renamed CARES. This program performed fast-fracture reliability and failure probability analysis of ceramic components. SCARE was built as a postprocessor to MSC/NASTRAN. Using MSC/NASTRAN output of the stress state in a component, SCARE performed the crack growth and structural reli­ability analysis of the component.[875] Upgrades and a very comprehensive program description and user’s guide were introduced in 1990.[876] In 1993, an extension, CARES/LIFE, was developed to calculate the time depen­dence of the reliability of a component as it is subjected to testing or use. This was accomplished by including the effects of subcritical crack growth over time.[877] Another 1993 upgrade, CCARES (for CMC CARES), added the capability to analyze components made from ceramic matrix composite (CMC) materials, rather than just macroscopically isotropic materials.[878] CARES/PC, introduced in 1994 and made publicly available through COSMIC, ran on a personal computer but offered a more lim­ited capability (it did not include fast-fracture calculations).[879]

R&D Magazine gave an R&D 100 Award jointly to NASA Lewis and to Philips Display Components for application of CARES/Life to the development of an improved television picture tube in 1995. "Cares/ Life has been in high demand world-wide, although present technology transfer efforts are entirely focused on U. S.-based organizations. Success stories can be cited in numerous industrial sectors, including aerospace, automotive, biomedical, electronic, glass, nuclear, and conventional power-generation industries.”[880]

Integrated Composite Analyzer (ICAN) was developed in the early 1980s to perform design and analysis of multilayered fiber composites. ICAN considered hygrothermal (humidity-temperature) conditions as well as mechanical loads and provided results for stresses, stress con­centrations, and locations of probable delamination.[881] ICAN was used extensively for design and analysis of composite space antennas and for analysis of engine components. Upgrades were developed, includ­ing new capabilities and a version that ran on a PC in the early 1990s.[882] ICAN was adapted (as ICAN/PART) to analyze building materials under a cost-sharing agreement with Master Builders, Inc., in 1995.[883]

Goodyear began working with Glenn in 1995 to apply Glenn’s Micromechanics Analysis Code (MAC) to tire design. The relationship was formed, in part, as a result of Glenn’s involvement with the Great Lakes Industrial Technology Center (GLITeC) and the Consortium for the Design and Analysis of Composite Materials. NASA worked with Goodyear to tailor the code to Goodyear’s needs and provided onsite training. MAC was used to assess the effects of chord spacing, ply and belt configurations, and other tire design parameters. By 2002, Goodyear had several tires in production that had benefitted from the MAC design analysis capabilities. Dr. Steven Arnold was the Glenn point of contact in this effort.[884]