Characterization of low-cycle multiaxial fatigue by a plastic fracture mechanics model

Conference · Sun Dec 01 04:00:00 EST 1996

OSTI ID:403229

Wang, Y; Pan, J ^[1]

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1. Univ. of Michigan, Ann Arbor, MI (United States)

Most mechanical components and structures are subjected to cyclic service loads. Fatigue cracks may appear due to these cyclic service loads. Currently, there are three major approaches to estimate fatigue life, namely, the stress-based approach, the strain-based approach, and the fracture mechanics approach. Here, the near-tip fields of small cracks in power-law hardening materials are investigated under plane-stress, general yielding, and mixed mode I and II conditions by finite element analyses. The characteristics of the near-tip strain fields suggest that Case multiaxial fatigue theories can be explained by a fracture mechanics crack growth criterion based on the maximum effective strain of the near-tip fields for small cracks under general yielding conditions. The constant effective stress contours representing the intense straining zones near the tip are also presented. The results of the J integral from finite element analyses are used to construct a fatigue crack growth criterion for Case A cracks. Based on the concept of the characterization of fatigue crack growth by the J integral, the trend of constant J integral contours on the {Gamma}-plane for Case A cracks in compared well with those of constant fatigue life and constant crack growth rate obtained from experiments.

• OSTI ID: 403229
• Report Number(s): CONF-960706--; ISBN 0-7918-1770-9
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
CRACK PROPAGATION
EQUIPMENT
FATIGUE
FINITE ELEMENT METHOD
INCONEL 718
MECHANICAL STRUCTURES