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Title: Separation of crack extension modes in composite delamination problems

Abstract

In the analysis of composite delamination problems, the magnitudes of Mode 1 and Mode 2 stress intensity factors or energy release rates are typically not unique, due to oscillatory behavior of near-tip stresses and displacements. This behavior currently limits the ability to consistently apply interfacial fracture mechanics to predict composite delamination. The virtual crack closure technique (VCCT) is a method used to extract Mode 1 and Mode 2 components of energy release rates from finite element fracture models. Energy release rate components extracted from an oscillatory delamination model using the VCCT are dependent on the virtual crack extension length, {Delta}. In this paper, a recently-developed modified VCCT from the literature is used to extract {Delta}-independent energy release rate quantities for composite delamination problems where the delamination occurs between two plies or ply groups modeled as in-plane orthotropic materials. Numerical cases studied are taken from existing work in the literature. For the cases studied, results show that mode mix values resulting from application of the modified VCCT are comparable to those obtained via existing methods. Some mode mix predictions obtained (in the literature) using existing methods lie outside the range of reasonable values for such problems, however. The {Delta}-independent energy releasemore » rate quantities extracted using the modified VCCT can serve as guides for testing the convergence of finite element models. This technique also has potential as a consistent method for extracting energy release rate quantities from numerical models of composite delamination.« less

Authors:
;  [1]
  1. Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Mechanical Engineering
Publication Date:
OSTI Identifier:
566517
Report Number(s):
CONF-950569-
Journal ID: ISSN 1040-3086; TRN: IM9805%%171
Resource Type:
Conference
Resource Relation:
Conference: 6. ASTM symposium on composites: fatigue and fracture, Denver, CO (United States), 16-18 May 1995; Other Information: PBD: 1997; Related Information: Is Part Of Composite materials: Fatigue and fracture (sixth volume); Armanios, E.A. [ed.]; PB: 579 p.; ASTM special technical publication 1285
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPOSITE MATERIALS; FRACTURE MECHANICS; STRESS INTENSITY FACTORS; CRACK PROPAGATION; FAILURES; CALCULATION METHODS

Citation Formats

Beuth, J L, and Narayan, S H. Separation of crack extension modes in composite delamination problems. United States: N. p., 1997. Web.
Beuth, J L, & Narayan, S H. Separation of crack extension modes in composite delamination problems. United States.
Beuth, J L, and Narayan, S H. Wed . "Separation of crack extension modes in composite delamination problems". United States.
@article{osti_566517,
title = {Separation of crack extension modes in composite delamination problems},
author = {Beuth, J L and Narayan, S H},
abstractNote = {In the analysis of composite delamination problems, the magnitudes of Mode 1 and Mode 2 stress intensity factors or energy release rates are typically not unique, due to oscillatory behavior of near-tip stresses and displacements. This behavior currently limits the ability to consistently apply interfacial fracture mechanics to predict composite delamination. The virtual crack closure technique (VCCT) is a method used to extract Mode 1 and Mode 2 components of energy release rates from finite element fracture models. Energy release rate components extracted from an oscillatory delamination model using the VCCT are dependent on the virtual crack extension length, {Delta}. In this paper, a recently-developed modified VCCT from the literature is used to extract {Delta}-independent energy release rate quantities for composite delamination problems where the delamination occurs between two plies or ply groups modeled as in-plane orthotropic materials. Numerical cases studied are taken from existing work in the literature. For the cases studied, results show that mode mix values resulting from application of the modified VCCT are comparable to those obtained via existing methods. Some mode mix predictions obtained (in the literature) using existing methods lie outside the range of reasonable values for such problems, however. The {Delta}-independent energy release rate quantities extracted using the modified VCCT can serve as guides for testing the convergence of finite element models. This technique also has potential as a consistent method for extracting energy release rate quantities from numerical models of composite delamination.},
doi = {},
journal = {},
issn = {1040-3086},
number = ,
volume = ,
place = {United States},
year = {1997},
month = {12}
}

Conference:
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