Fatigue growth and closure of short cracks

A study has been carried out to investigate the growth and closure behavior of short cracks in 2024-T351 aluminum alloy and four different conditions of 4340 steel using through thickness cracks of straight fronts. The experiments were carried out to study the influence of stress level, stress ratio, yield strength and prior austenitic grain A sizes in notched and unnotched specimens. The stereoimaging technique was developed and adapted to obtain crack closing and opening points, and also near tip displacement fields. Experimental results are presented with a general discussion. It was found that long cracks showed good correlation when analyzed in terms of effective stress intensity range. However,correlations were poor for short cracks. lt was found that short cracks show less closure behavior than long cracks. The estimates of initial crack lengths based on linear elastic data were made. These estimates differed significantly from the actual initial crack lengths for completely reversed cycling tests. Suggestions have been made to the equivalent initial flaw size approach and conclusions have been drawn.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Mechanics

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1988

Author dc:creator

• Iyyer, Nagaraja S.

Chair dc:contributor.committeechair

• Dowling, N.E.

Committee members dc:contributor.committeemember

• Smith, C.W.
• Reddy, Junuthula N.
• Duke, John C. Jr.
• Swanson, Robert E.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/52324

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/52324