Tensile testing apparatus
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsLinda B. Blackburn, John R. Ellingsworth
Life of this patent
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Abstract
An improved mechanical extensometer for use with a constant load creep test machine 10, wherein the dead weight of the extensometer is counterbalanced by two pairs of weights 70,90 and 80,100 connected through a pulley system 68, 78, 88 and 98 to rod extension 55,56 and 59,60, leading into the furnace 20 where test sample S is undergoing elevated temperature (above 500.degree. F.) tensile testing. Novel gripper surfaces, conical tip 119 and flat surface 122, are provided in each sample engaging platens 38 and 40 to reduce the grip pressure normally required for attachment of the extensometer to the specimen and reduce initial specimen bending normally associated with foil-gage metal testing.
Claims6
In combination with an extensometer for accurately measuring strain on foil-gage type materials under elevated temperature test conditions including a displacement transducer strain measuring device, a clam shell type furnace, a pair of platens for supporting a test specimen within the furnace, and means for exerting a constant tensile load on the test sample supported therein, the improvement therewith comprising:
- counterbalance means connected to each of said pair of platens to offset the weight contribution of the extensometer on the test specimen,
- sample engaging means forming part of each of said pair of platens, said sample engaging means in each said platen comprising a first flat edge surface and a second conical tip surface,
- said flat edge surface and said conical tip surface engaging and retaining a foil-gage type test specimen therebetween, and
- means for adjusting relative movement of said flat edge surface and said conical tip surface to adjust and maintain the engagement thereof with the test specimen.
An improved extensometer for accurately measuring strain on foil-gage materials under elevated temperature test conditions comprising in combination with a constant creep load test machine and a clam-shell type furnace,
- sample engaging chucks for retaining a foil-gage test sample within the test machine and having load applying means connected thereto for applying a constant tensile load on the sample,
- an extensometer secured to the test section of the test sample within the furnace,
- said extensometer including a first pair of spaced platens attached to the test section of the test sample,
- said first pair of spaced furnace platens being individually and positively connected to a second pair of spaced platens disposed exteriorly of the furnace such that any linear relative movement of said first pair of spaced platens will be transferred to an identical relative linear movement of said second pair of spaced platens,
- means attached to and measuring linear displacement of said second pair of spaced platens as a function of strain on the test sample attached to said first pair of spaced platens, and
- weight means connected to said first pair of platens to counterbalance the combined weight of the extensometer acting on the test sample.
Dependencies are inferred from the claim text.