SYMPOSIA PAPER Published: 01 January 1958
STP45768S

Sudden Fracture of Machine Parts and Structure Elements

Source

Many papers have been devoted to the problem of the initiation and propagation of fatigue cracks (1–5). It has been established that the rate of crack propagation depends upon the magnitude of acting stresses. When the stresses approximate the endurance limit, the crack propagates slowly, and final fracture might occur after a long period of time. When the stresses are constant and greatly exceed the endurance limit, the rate of crack propagation is higher, and final fracture in this case might occur a short period of time after the crack initiation. However, machine and structural elements often work under so-called “non-constant” conditions, that is with loads of small value acting over a long period of time alternating with overloads of considerable magnitude but of short duration. It is this type of loading that might cause the transition from pure fatigue failure to sudden brittle fracture. The sudden brittle fracture develops in two main stages: The first stage presents the initiation of a fatigue crack as a result of cumulative damage caused by momentary overloads. The crack after its initiation may be regarded as a sharp notch. The second stage presents the sudden brittle fracture under a single application of overload.

Author Information

Uzhik, G., V.
Institute of Mechanical Engineering, Academy of Science of the U.S.S.R., Moscow
Galperin, M., J.
Institute of Mechanical Engineering, Academy of Sciences of the U.S.S.R., Moscow
Zooykova, A., A.
Institute of Mechanical Engineering, Academy of Sciences of the U.S.S.R., Moscow
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Details
Developed by Committee: E08
Pages: 132–141
DOI: 10.1520/STP45768S
ISBN-EB: 978-0-8031-6716-2
ISBN-13: 978-0-8031-6553-3