GLTRS--Glenn
TITLE AND SUBTITLE:
Mechanical Testing of IN718 Lattice Block Structures

AUTHOR(S):
David L. Krause, John D. Whittenberger, Pete T. Kantzos, and Mohan G. Hebsur

REPORT DATE:
January 2002

FUNDING NUMBERS:
WU-714-04-50-00

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-13124

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, DC 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-2002-211325

SUPPLEMENTARY NOTES:
Prepared for the 131st Annual Meeting and Exhibition sponsored by the Minerals, Metals, and Materials Society
Seattle, Washington, February 17-21, 2002. David L. Krause and John D. Whittenberger, NASA Glenn Research Center; Pete T. Kantzos and Mohan G. Hebsur, Ohio Aerospace Institute, 22800 Cedar Point Road, Brook Park, Ohio 44142. Responsible person, David L. Krause, organization code 5920, 216-433-5465.

ABSTRACT:
Lattice block construction produces a flat, structurally rigid panel composed of thin ligaments of material arranged in a three-
dimensional triangulated truss-like structure. Low-cost methods of producing cast metallic lattice block panels are now available that greatly expand opportunities for using this unique material system in today's high-performance structures. Additional advances are being made in NASA's Ultra Efficient Engine Technology (UEET) program to extend the lattice block concept to superalloy materials. Advantages offered by this combination include high strength, light weight, high stiffness and elevated temperature capabilities. Recently under UEET, the nickel-based superalloy Inconel 718 (IN718) was investment cast into lattice block panels with great success. To evaluate casting quality and lattice block architecture merit, individual ligaments, and structural subelement specimens were extracted from the panels. Tensile tests, structural compression, and bending strength tests were performed on these specimens. Fatigue testing was also completed for several bend test specimens. This paper first presents metallurgical and optical microscopy analysis of the castings. This is followed by mechanical test results for the tensile ligament tests and the subelement compression and bending strength tests, as well as for the fatigue tests that were performed. These tests generally showed comparable properties to base IN718 with the same heat treatment, and they underscored the benefits offered by lattice block materials. These benefits might be extended with improved architecture such as face sheets.

SUBJECT TERMS:
Structures; Trusses; Cells; Investment casting; Inconel; Mechanical properties; Deformation; Tensile strength; Modulus of elasticity; Compressive strength; Bending; Flexural strength; Fatigue life

NUMBER OF PAGES:
16

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