Misalignment-Induced Bending in Pin-Loaded Tensile-Creep Specimens

Published

January 1, 2001

Author(s)

Ralph Krause, Sheldon M. Wiederhorn, J J. Kuebler

Abstract

In this paper, we examined the possibility that elastic bending induced by load misalignment can affect creep measurements on pin-loaded tension specimens of silicon nitride(Si₃N₄). We have shown that elastic bending ato room temperature can be as great as 42% of the axial strain when clean pins were used but was reduced to {difference} 3% when lubricated pins wereused. Creep tests at the same applied stress and temperature were conducted on two groups of Si₃N₄ test specimens: one group used clean pins, and the other group used lubricated pins. By measuring the shapes of the specimens before and after the creep tests, we have determined that the loading holes were slightly misaligned before the creep tests and that small amounts of bending were induced by the creep tests. Bending occurred both in the gauge section of the specimen and in the transition region between the gauge section and the heads of the specimen (the latter phenomenon is defined as hinge bending). Our study indicated that the secondary creep rate , the hinge bending, and the bending of the gauge section was not dependent on pin lubrication, because the results from the clean and lubricated groups were statistically indistinguishable. Hinge bending was dependent on initial misalignment of the loading holes, whereas bending of the gauge section was independent of such factors.

Citation

Journal of the American Ceramic Society

Volume

84

Issue

No. 1

Pub Type

Journals

Keywords

misalignment bending, pin-loaded specimens, tensile creep

Citation

Krause, R. , Wiederhorn, S. and Kuebler, J. (2001), Misalignment-Induced Bending in Pin-Loaded Tensile-Creep Specimens, Journal of the American Ceramic Society (Accessed April 26, 2024)