SYMPOSIA PAPER Published: 01 January 1979
STP34911S

Structural Memory of Cracked Components Under Irregular Loading

Source

The small scale yielding (SSY) relationships for stationary cracks cannot describe the local elastic-plastic behavior at a crack tip when irregular loading is considered. As a consequence, linear models for crack growth prediction fail. Nonlinear crack growth behavior (retardation, acceleration) is due mainly to load interaction effects which are governed by memory rules. As to stationary cracks, memory which is based on the local behavior (closed hysteresis loops) can be described by reaching certain load levels. Extended to crack growth problems, the “structural memory” criterion is described by striking elastic-plastic boundaries. This points up the central role that the development of plastic zone sizes as a function of crack length and load history plays. The concern of the paper is with those structural analysis aspects under the assumption of perfectly plastic material properties. SSY plastic zone formulae are derived for the peak overload/underload case which are shown to be of central importance for describing the nonlinear effects due to any irregular loading history. It is demonstrated, in principle, how crack closure can be taken into account.

Author Information

Führing, H
Laboratorium fur Betriebsfestigkeit, Darmstadt, Germany
Seeger, T
Institut für Statik und Stahlbau, Technical University of Darmstadt, Germany
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Details
Developed by Committee: E08
Pages: 144–167
DOI: 10.1520/STP34911S
ISBN-EB: 978-0-8031-4746-1
ISBN-13: 978-0-8031-0364-1