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Title: Three-dimensional crack growth assessment by microtopographic examination

Abstract

The initial stage of the stable tearing process in two 2.3 mm sheet 2024-T3 aluminum alloy M(T) specimens are analyzed using fracture surface microtopography reconstruction techniques. The local crack tip opening angles (CTOA) in the interior of the specimens are determined relative to both crack extension and through-thickness position. The microtopographic analysis of cracks grown in the L-T and T-L orientations reveal that interior CTOA is comparable to those measured on the surface using standard optical analysis methods. Similar to surface CTOA results, interior (mid-thickness) CTOA exhibit a transient behavior; CTOA transitions from high angles, at near crack initiation, to a lower steady-state value of 5 deg. and 4.2 deg. for L-T and T-L, respectively, at crack lengths greater than 1.5mm. Fracture surface topographic projection maps are used to study the evolution of crack front tunneling during the initial stage of the fracture process. Stable tearing initiates at mid-thickness followed by a crack front tunneling process to a depth of approximately 2mm. A brief discussion of the basis of the fracture process reconstruction method is provided and comments on the general utility of microtopographic fracture surface examination for general assessment of elastic-plastic and fully-plastic fracture processes are made.

Authors:
 [1];  [2]
  1. Idaho National Engineering Lab., Idaho Falls, ID (United States)
  2. National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center
Publication Date:
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
597679
Report Number(s):
CONF-9406335-
Journal ID: ISSN 1040-3094; TRN: IM9812%%130
Resource Type:
Conference
Resource Relation:
Conference: 26. national symposium on fracture mechanics, Idaho Falls, ID (United States), 28-30 Jun 1994; Other Information: PBD: 1995; Related Information: Is Part Of Fracture mechanics: 26. volume; Reuter, W.G. [ed.] [Lockheed Martin Idaho Technologies, Idaho Falls, ID (United States)]; Underwood, J.H. [ed.] [Army Armament Research and Development Center, Watervliet, NY (United States)]; Newman, J.C. Jr. [ed.] [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center]; PB: 853 p.; ASTM special technical publication 1256
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM BASE ALLOYS; CRACK PROPAGATION; FRACTURE MECHANICS; SHEETS; MAPPING; SURFACE PROPERTIES; CALCULATION METHODS

Citation Formats

Lloyd, W R, and Piascik, R S. Three-dimensional crack growth assessment by microtopographic examination. United States: N. p., 1995. Web.
Lloyd, W R, & Piascik, R S. Three-dimensional crack growth assessment by microtopographic examination. United States.
Lloyd, W R, and Piascik, R S. 1995. "Three-dimensional crack growth assessment by microtopographic examination". United States.
@article{osti_597679,
title = {Three-dimensional crack growth assessment by microtopographic examination},
author = {Lloyd, W R and Piascik, R S},
abstractNote = {The initial stage of the stable tearing process in two 2.3 mm sheet 2024-T3 aluminum alloy M(T) specimens are analyzed using fracture surface microtopography reconstruction techniques. The local crack tip opening angles (CTOA) in the interior of the specimens are determined relative to both crack extension and through-thickness position. The microtopographic analysis of cracks grown in the L-T and T-L orientations reveal that interior CTOA is comparable to those measured on the surface using standard optical analysis methods. Similar to surface CTOA results, interior (mid-thickness) CTOA exhibit a transient behavior; CTOA transitions from high angles, at near crack initiation, to a lower steady-state value of 5 deg. and 4.2 deg. for L-T and T-L, respectively, at crack lengths greater than 1.5mm. Fracture surface topographic projection maps are used to study the evolution of crack front tunneling during the initial stage of the fracture process. Stable tearing initiates at mid-thickness followed by a crack front tunneling process to a depth of approximately 2mm. A brief discussion of the basis of the fracture process reconstruction method is provided and comments on the general utility of microtopographic fracture surface examination for general assessment of elastic-plastic and fully-plastic fracture processes are made.},
doi = {},
url = {https://www.osti.gov/biblio/597679}, journal = {},
issn = {1040-3094},
number = ,
volume = ,
place = {United States},
year = {Sun Dec 31 00:00:00 EST 1995},
month = {Sun Dec 31 00:00:00 EST 1995}
}

Conference:
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