SEDL / STP / STP803V2-EB / STP36765S

Some Salient Features of the Tearing Instability Theory

Ernst, HA
Senior engineer, Westinghouse R&D Center, Pittsburgh, Pa.

Pages: 23    Published: Jan 1983

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Abstract

In this work the problem of the stability of a system deformed under displacement and load-controlled conditions is examined. The instability conditions are found from the load versus displacements, P-δ, characteristics of the system and the stiffness of the structure, KM, on a completely general basis. The analysis is performed for the system in series with a spring under displacement control and for the system in parallel with the spring under load-controlled conditions.

In addition it is shown that the conditions for instability found for both situations using the tearing instability theory are in complete agreement with those obtained under a completely general basis. As a result the tearing instability theory is proven to be always valid in the sense that instability will occur if and only if T^app > T^mat.

Finally, a small experimental program on a nickel-chromium-molybdenum-vanadium rotor steel was conducted in order to prove that structures can be designed to assure stable crack growth under load-controlled conditions beyond maximum load.