SYMPOSIA PAPER Published: 01 January 2000
STP13510S

Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequencing Effects

Source

Cumulative fatigue behavior of a wrought cobalt-base superalloy, Haynes 188, was investigated at 538°C under various single-step sequences of axial and torsional loading conditions. Initially, fully-reversed, axial and torsional fatigue tests were conducted under strain control at 538°C on thin-walled tubular specimens to establish baseline fatigue life relationships. Subsequently, four sequences (axial/axial, torsional/torsional, axial/torsional, and torsional/axial) of two load-level fatigue tests were conducted to characterize both the load-order (high/low) and load-type sequencing effects. For the two load-level tests, summations of life fractions and the remaining fatigue lives at the second load level were computed by the Miner's linear damage rule (LDR) and a nonlinear damage curve approach (DCA). In general, for all four cases predictions by LDR were unconservative. Predictions by the DCA were within a factor of two of the experimentally observed fatigue lives for a majority of the cumulative axial and torsional fatigue tests.

Author Information

Kalluri, S
Ohio Aerospace Institute, NASA Glenn Research Center, Cleveland, OH
Bonacuse, PJ
U.S. Army Research Laboratory, NASA Glenn Research Center, Cleveland, OH
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Details
Developed by Committee: E08
Pages: 281–301
DOI: 10.1520/STP13510S
ISBN-EB: 978-0-8031-5435-3
ISBN-13: 978-0-8031-2865-1