SYMPOSIA PAPER Published: 01 January 1959
STP39312S

Cycle-Dependent Stress Relaxation

Source

Time-dependent relaxation of stress in metal held in a strained state is a well known phenomenon. There also exists a cycle-dependent relaxation of stress which occurs under conditions of repeated straining. To investigate this type of behavior, the mean strain and amplitude of alternating strain is held constant in axial fatigue tests of SAE 4340, and the mean stress is measured as a function of the number of strain repetitions. An analysis utilizing an assumed stress-microstrain relationship is employed to study the relaxation in terms of the condition of the material, the initial and control conditions of the test, and the cycles of strain repetition. Push-pull fatigue data is also reported in which the mean strain rather than the mean stress is held constant throughout the fatigue test. The practical significance of these findings is discussed, especially as relates to the fading of residual stresses in members subjected to fatigue loading.

Author Information

Morrow, J
Theoretical and Applied Mechanics, University of Illinois, Urbana, Ill.
Sinclair, GM
Theoretical and Applied Mechanics, University of Illinois, Urbana, Ill.
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Details
Developed by Committee: E08
Pages: 83–109
DOI: 10.1520/STP39312S
ISBN-EB: 978-0-8031-5622-7
ISBN-13: 978-0-8031-5621-0