Accession Number:

ADA151289

Title:

Entropy Production during Fatigue as a Criterion for Failure. A Local Theory of Fracture in Engineering Materials.

Descriptive Note:

Final technical rept., 15 Aug 82-31 Oct 84,

Corporate Author:

NEBRASKA UNIV LINCOLN COLL OF ENGINEERING AND TECHNOLOGY

Personal Author(s):

• Whaley,P. W.

Report Date:

1984-12-15

Pagination or Media Count:

94.0

Abstract:

A mathematical model of fatigue crack nucleation initiation, and propagation is described using irreversible thermodynamics to quantify the damage caused by plastic straining. A mathematical model for local random yielding is used to derive a local theory of fracture and fatigue crack growth. The classical results of linear elastic fracture mechanics are reproduced necessary and sufficient conditions for crack extension, critical stress and crack length, and sigmoidal shape of the crack growth curve. However, this model is not limited to small-scale yielding, includes treatment of loading history, and can be applied to crack growth retardation and closure as well as combined loading and spectrum loading. Originator-supplied keywords include Fatigue crack initiation Fatigue crack nucleation Fatigue damage Fatigue testing Fatigue theories Material damping measurements Material damping theories Fatigue crack growth. Author.

Descriptors:

• *CRACKING(FRACTURING)
• *NUCLEATION
• *FATIGUE(MECHANICS)
• *ENTROPY
• MATHEMATICAL MODELS
• DAMAGE
• THERMODYNAMICS
• ELASTIC PROPERTIES
• STRAIN(MECHANICS)
• CRACK PROPAGATION
• FATIGUE TESTS(MECHANICS)
• IRREVERSIBLE PROCESSES
• RETARDATION

Subject Categories:

• Mechanics
• Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE