Accession Number:

ADA090596

Title:

A Nonarbitrary Fatigue Crack Size Concept to Predict Total Fatigue Lives

Descriptive Note:

Final rept. Feb 1977-Jul 1979

Corporate Author:

ILLINOIS UNIV AT URBANA MATERIALS ENGINEERING RESEARCH LAB

Personal Author(s):

• Kurath, Peter
• Socie, D. F.
• Morrow, Jo Dean

Report Date:

1979-12-01

Pagination or Media Count:

62.0

Abstract:

A method combining strain cycle fatigue and fracture mechanics concepts to predict a nonarbitrary crack initiation size, ai, is presented. The nonarbitrary crack size is used as a demarcation between fatigue crack initiation and propagation methods of analysis. Geometry, mean stress, and stress range all influence the value of ai. Five different geometries were analyzed and tested at various load levels and two load ratios. Constant amplitude loading and initial incremental overload are considered. Specimens of an aluminum alloy, Al 7075-T651, were tested in the as-machined condition. Correlations between the analytical life predictions and experimental values of life fell within a factor of two in most cases.

Descriptors:

• *FATIGUE LIFE
• *SIZES(DIMENSIONS)
• *CRACK PROPAGATION
• *CRACKS
• *MATHEMATICAL PREDICTION
• MATHEMATICAL MODELS
• ALUMINUM ALLOYS
• FATIGUE(MECHANICS)
• FRACTURE(MECHANICS)

Subject Categories:

• Numerical Mathematics
• Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE