Separation of crack extension modes in composite delamination problems
Abstract
In order to predict composite delamination resistance, an applied stress intensity factor, K, or energy release rate, G, must be compared to a modedependent critical value of K or G from experiment. In the interfacial fracture analysis of most composite applications and some tests, the mode of crack extension is not uniquely defined. It is instead a function of distance from the crack tip due to the neartip oscillatory singularity. The virtual crack closure technique (VCCT) is a method used to extract mode I and mode II energy release rate components from numerical (typically finite element) models. Crack extension modes extracted from oscillatory analyses using the VCCT are a function of the virtual crack extension length, {Delta}. In this work, a modified method is presented for using the VCCT to extract crack extension modes for the case of an interface crack between two inplane orthotropic materials. The method does not attempt to alter the analysis to eliminate its oscillatory behavior (e.g. by changing material properties or by embedding the crack in a homogeneous interlayer). Instead, the argument is made that the oscillatory behavior is nonphysical and that if its effects were separated from VCCT quantities, then consistent, {Delta}independent modes ofmore »
 Authors:

 Carnegie Mellon Univ., Pittsburgh, PA (United States)
 Publication Date:
 OSTI Identifier:
 175168
 Report Number(s):
 CONF950686
TRN: 95:0061110081
 Resource Type:
 Conference
 Resource Relation:
 Conference: Joint applied mechanics and materials summer meeting, Los Angeles, CA (United States), 2830 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of AMD  MD `95: Summer conference; PB: 520 p.
 Country of Publication:
 United States
 Language:
 English
 Subject:
 36 MATERIALS SCIENCE; 99 MATHEMATICS, COMPUTERS, INFORMATION SCIENCE, MANAGEMENT, LAW, MISCELLANEOUS; COMPOSITE MATERIALS; CRACK PROPAGATION; FINITE ELEMENT METHOD; INTERFACES; STRESS INTENSITY FACTORS; THERMODYNAMICS
Citation Formats
Beuth, J L. Separation of crack extension modes in composite delamination problems. United States: N. p., 1995.
Web.
Beuth, J L. Separation of crack extension modes in composite delamination problems. United States.
Beuth, J L. Sun .
"Separation of crack extension modes in composite delamination problems". United States.
@article{osti_175168,
title = {Separation of crack extension modes in composite delamination problems},
author = {Beuth, J L},
abstractNote = {In order to predict composite delamination resistance, an applied stress intensity factor, K, or energy release rate, G, must be compared to a modedependent critical value of K or G from experiment. In the interfacial fracture analysis of most composite applications and some tests, the mode of crack extension is not uniquely defined. It is instead a function of distance from the crack tip due to the neartip oscillatory singularity. The virtual crack closure technique (VCCT) is a method used to extract mode I and mode II energy release rate components from numerical (typically finite element) models. Crack extension modes extracted from oscillatory analyses using the VCCT are a function of the virtual crack extension length, {Delta}. In this work, a modified method is presented for using the VCCT to extract crack extension modes for the case of an interface crack between two inplane orthotropic materials. The method does not attempt to alter the analysis to eliminate its oscillatory behavior (e.g. by changing material properties or by embedding the crack in a homogeneous interlayer). Instead, the argument is made that the oscillatory behavior is nonphysical and that if its effects were separated from VCCT quantities, then consistent, {Delta}independent modes of crack extension could be defined. Knowledge of neartip fields is used to determine the explicit {Delta} dependence of VCCT parameters. Energy release rates are then defined with the oscillatory {Delta} dependence factored out. This modified VCCT method is applied to results from finite element analyses, showing that {Delta}independent modes of crack extension result. The modified VCCT approach shows potential as a consistent method of extracting crack extension modes. The {Delta}independent modes extracted using the modified approach can also serve as guides to test the convergence of finite element solutions.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1995},
month = {12}
}