Fatigue testing apparatus
AssigneeThe United States of America as represented by the United States National Aeronautics and Space Administration
InventorRobert J. Buzzard
Life of this patent
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Abstract
Apparatus is provided for obtaining a single crack in fatigue loading which emanates from a predetermined starting notch in a test specimen. This crack propagates in a direction in line with that of the applied Mode II load. The loading may be performed either monotonically or in a cyclic fatigue.
Claims20
Apparatus for testing materials under Mode II loading wherein the material being tested is in the form of a plate having a pair of spaced loading holes with a centrally disposed notch extending from one edge between said holes toward a full cutout in the opposite edge thereof comprising
- a fixed clevis and movable clevis mounted on a testing machine, each of said clevises having a centrally disposed slot for receiving said plate so that the central axis of loading passes through the centerline of said centrally disposed notch,
- a first pin carried by said fixed clevis for insertion into one of said spaced loading holes for transmitting a force thereto in one direction,
- a second pin carried by said movable clevis for insertion into the other of said spaced loading holes for transmitting a force thereto in the opposite direction thereby producing a rotational moment in said plate, and
- a third pin carried by said movable clevis for mating with said full cutout thereby arresting rotational moment.
An apparatus for Mode II loading a test specimen having a notch with a loading hole on each side thereof using clevises carrying pins which pass through said loading holes for transmitting a loading force from a testing machine so that the central axis of loading passes through the centerline of said notch with a resulting rotational moment in said specimen, the improvement comprising
- a full cutout in said test specimen opposite said notch, and
- a member mounted on one of said clevises for mating with said cutout thereby arresting said rotational moment.
Dependencies are inferred from the claim text.