SEDL / STP / STP511-EB / STP35405S

Comparison of Scatter Under Program and Random Loading and Influencing Factors

Jacoby, GH
Darmstadt, Germany

Nowack, H
Institut fuer Werktoff-Forschung, Porz-Wahn, Germany

Pages: 14    Published: Jan 1972

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Abstract

The paper deals with the scatter under program and random loading. For the explanation of the results, constant amplitude tests and tests with biharmonic loading are also included in the study. The basis of the comparison of the data is the logarithmic normal distribution and its parameters. It was found that scatter under program, random, and biharmonic loading is identical and is similar to the scatter derived in constant amplitude tests in the life range of about 10⁵ load cycles. This is true for life as well as for crack propagation. Miner's rule overestimates the scatter, which occurs in tests simulating irregularly varying service loads. An important influence on scatter is due to the testing machine.