Accession Number : ADA306625

Title :   Fracture Testing of Large-Scale Thin-Sheet Aluminum Alloy.

Descriptive Note : Final rept.,

Corporate Author : NATIONAL INST OF STANDARDS AND TECHNOLOGY GAITHERSBURG MD

Personal Author(s) : DeWit, R. ; Fields, R. J. ; Low, S. R., III ; Harne, D. E. ; Foecke, T.

PDF Url : ADA306625

Report Date : FEB 1996

Pagination or Media Count : 32

Abstract : A series of fracture tests on large-scale, precracked, aluminum alloy panels were carried out to examine and characterize the process by which cracks propagate and link up in this material. Extended grips and test fixtures were specially designed to tension load the panel specimens in a l780-kN capacity universal testing machine. Single sheets of bare 2024-T3 aluminum alloy, approximately 4 m high, 2.3 m wide, and 1 mm thick were fabricated with simulated through cracks oriented horizontally at midheight. Using existing information, a test matrix was set up to explore regions of failure controlled by fracture mechanics, with additional tests near the boundary between plastic collapse and fracture. In addition, a variety of multiple site damage (MSD) configurations were included to distinguish between various proposed linkage mechanisms. All tests but one used antibuckling guides. Three specimens were fabricated with a single central crack, six others had multiple cracks on each side of the central crack, and one had a single crack but no antibuckling guides. The results of each fracture event were recorded on various media: film, video, computer, magnetic tape, and occasionally optical microscope. The video showed the crack tip with a load meter in the field of view, using motion picture film for one tip and super VHS video tape for the other. The computer recorded the output of the testing machine load cell, the stroke, and the twelve strain gages at 1.5-second intervals. A wideband FM magnetic tape recorder was used to record data from the same sources. The data were analyzed by two different procedures: (1) the plastic zone model based on the residual strength diagram and (2) the R-curve.

Descriptors :   *ALUMINUM ALLOYS, *FRACTURE(MECHANICS), *SHEETS, *THINNESS, TEST AND EVALUATION, OPTICAL EQUIPMENT, DAMAGE, MODELS, PANELS, CRACKS, SITES, TEST METHODS, STRENGTH(MECHANICS), RESIDUALS, TENSION, STRAIN GAGES, PLASTIC PROPERTIES, MICROSCOPES, LINKAGES, COLLAPSE, DIAGRAMS, MAGNETIC TAPE, VIDEO TAPES, TEST FIXTURES, MOTION PICTURE FILM.

Subject Categories : Properties of Metals and Alloys
      Optics
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE