SEDL / STP / STP1332-EB / STP14976S

Sustained Fatigue Crack Growth Oblique to an Applied Load Using Geometric Constraint

Magill, MA
Associate Professor, Purdue University, West Lafayette, Indiana

Zwerneman, FJ
Professor, Oklahoma State University, Stillwater, Oklahoma

Pages: 16    Published: Jan 1999

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Abstract

This paper presents the results of a research project on fatigue crack growth driven by sustained mode I and II loading. This project involved developing and analyzing a flat plate specimen capable of sustaining crack growth on a plane oblique to the direction of the applied load. Several of these specimens were built and fatigue loaded in the laboratory. Using geometric constraint, the crack was forced to grow in a direction other than perpendicular to the load. The resulting crack front stabilized into a curved or warped shape rather than straight and flat. Based on finite element analyses of these curved specimen cracks, it is concluded that the stress intensity factors (SIFs) were predominantly mode I, with the mode II and III SIFs being negligible. It was also determined that the oblique cracks grew perpendicular to the maximum principal stress.