Accession Number : ADA250667

Title :   Mixed Model Fatigue Crack Growth Behavior in a High Strength Steel.

Descriptive Note : Final rept. Oct 89-Sep 91,

Corporate Author : DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT

Personal Author(s) : Link, Richard E.

Report Date : NOV 1991

Pagination or Media Count : 26

Abstract : Most of the currently available methods for predicting fatigue crack growth in structures do not consider effects due to mixed-mode loading. This is partly due to the limited information available concerning the fatigue crack growth under mixed mode loading. Previous investigations of mixed mode effects on fatigue crack growth have shown that under combined opening and in-plane shear loading, the cracks turn abruptly so that the in-plane shear mode is eliminated. Very little data is generated before the crack curvature eliminates the mixed-mode loading. The changing orientation of the crack during the test makes analysis of the problem difficult and may cloud the intrinsic fatigue crack growth rate behavior under mixed-mode loading. Situations can exist in engineering structures in which cracks may grow in a self-similar manner, even under the influence of mixed-mode loading. Examples of such situations are radial cracks in bearing rates and transverse cracks in rotating shafts under shear and bending loads. The cracks may not change orientation because the in-plane shear component is fully reversed. It is necessary to understand the effects of mixed mode loading on fatigue crack growth in order to properly predict the behavior of these components. Mixed mode, Fatigue, Crack growth, Predictive models, Ni-Cr-Mo steel

Descriptors :   *FATIGUE(MECHANICS), *CRACK PROPAGATION, *ALUMINUM, *STEEL, BEHAVIOR, BENDING, CRACKS, CURVATURE, MODELS, OPENINGS, RATES, STEEL, STRUCTURES, TEST AND EVALUATION, TRANSVERSE, FATIGUE TESTS(MECHANICS), SHEAR STRESSES, BEARING STRENGTH, PANELS, LOADS(FORCES), MECHANICAL PROPERTIES, CHEMICAL COMPOSITION, CYCLIC LOADS, NICKEL, CHROMIUM, MOLYBDENUM.

Subject Categories : Mechanics
      Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE