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Title: Finite deformation analysis of crack tip opening in elastic-plastic materials and implications for fracture initiation

Abstract

Analyses of the stress and strain fields around smoothly blunting crack tips in both non-hardening and hardening elastic-plastic materials, under contained plane strain yielding and subject to mode I opening loads, have been carried out by a finite element method suitably formulated to admit large geometry changes. The results include the crack tip shape and near-tip deformation field, and the crack tip opening displacement has been related to a parameter of the applied load, the J-integral. The hydrostatic stresses near the crack tip are limited due to the lack of constraint on the blunted tip, limiting achievable stress levels except in a very small region around the crack tip in power law hardening materials. The J-integral is found to be path independent except very close to the crack tip in the region affected by the blunted tip. Models for fracture are discussed in the light of these results including one based on the growth of voids. The rate of void growth near the tip in hardening materials seems to be little different from the rate in non-hardening materials when measured in terms of crack tip opening displacement, which leads to a prediction of higher toughness in hardening materials. It ismore » suggested that improvement of this model would follow from better understanding of void-void and void-crack coalescence and void nucleation, and some criteria and models for these are discussed. The implications of the finite element results for fracture criteria based on critical stress, strain or both are discussed with respect to transition of fracture mode and the angle of initial crack growth. Localization of flow is discussed as a possible fracture model and as a model for void-crack coalescence.« less

Authors:
Publication Date:
Research Org.:
Brown Univ., Providence, R.I. (USA). Div. of Engineering
Sponsoring Org.:
US Energy Research and Development Administration (ERDA)
OSTI Identifier:
7267600
Report Number(s):
COO-3084/44
DOE Contract Number:  
E(11-1)-3084
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRACKS; STRESS ANALYSIS; METALS; FRACTURE PROPERTIES; DEFORMATION; ELASTICITY; FINITE ELEMENT METHOD; PLASTICITY; STRAINS; STRESSES; ELEMENTS; MECHANICAL PROPERTIES; NUMERICAL SOLUTION; TENSILE PROPERTIES; 360103* - Metals & Alloys- Mechanical Properties

Citation Formats

McMeeking, R M. Finite deformation analysis of crack tip opening in elastic-plastic materials and implications for fracture initiation. United States: N. p., 1976. Web. doi:10.2172/7267600.
McMeeking, R M. Finite deformation analysis of crack tip opening in elastic-plastic materials and implications for fracture initiation. United States. https://doi.org/10.2172/7267600
McMeeking, R M. Sat . "Finite deformation analysis of crack tip opening in elastic-plastic materials and implications for fracture initiation". United States. https://doi.org/10.2172/7267600. https://www.osti.gov/servlets/purl/7267600.
@article{osti_7267600,
title = {Finite deformation analysis of crack tip opening in elastic-plastic materials and implications for fracture initiation},
author = {McMeeking, R M},
abstractNote = {Analyses of the stress and strain fields around smoothly blunting crack tips in both non-hardening and hardening elastic-plastic materials, under contained plane strain yielding and subject to mode I opening loads, have been carried out by a finite element method suitably formulated to admit large geometry changes. The results include the crack tip shape and near-tip deformation field, and the crack tip opening displacement has been related to a parameter of the applied load, the J-integral. The hydrostatic stresses near the crack tip are limited due to the lack of constraint on the blunted tip, limiting achievable stress levels except in a very small region around the crack tip in power law hardening materials. The J-integral is found to be path independent except very close to the crack tip in the region affected by the blunted tip. Models for fracture are discussed in the light of these results including one based on the growth of voids. The rate of void growth near the tip in hardening materials seems to be little different from the rate in non-hardening materials when measured in terms of crack tip opening displacement, which leads to a prediction of higher toughness in hardening materials. It is suggested that improvement of this model would follow from better understanding of void-void and void-crack coalescence and void nucleation, and some criteria and models for these are discussed. The implications of the finite element results for fracture criteria based on critical stress, strain or both are discussed with respect to transition of fracture mode and the angle of initial crack growth. Localization of flow is discussed as a possible fracture model and as a model for void-crack coalescence.},
doi = {10.2172/7267600},
url = {https://www.osti.gov/biblio/7267600}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1976},
month = {5}
}