The Crippling Strength of Compression Elements

Abstract

This paper consists of a review, primarily for the air-frame designer and stress analyst, of a new method of crippling strength analysis. Available test data on various aluminum, magnesium, and titanium alloys and steels are presented in terms of generalized parameters, based on the overall geometric configuration of the element and two mechanical properties of the material— the elastic modulus and compressive yield strength. The method applies to both formed and extruded elements and stiffened panels. The predictions of the method are checked by available test data on short-time crippling at elevated temperatures. Similarly, the method is extended to the creep crippling problem by a suitable definition of the time-dependent yield strength under creep conditions. Finally, the efficiencies of various materials in crippling applications under elevated temperature conditions are reviewed and simple test methods are proposed for rapidly determining the crippling strength of new materials under various environmental conditions.