The Influence of Crystallographic Orientation of the Crack Plane and Crack Front on the Fracture of Tungsten Single Crystals

1994 ◽  
Vol 367 ◽  
Author(s):  
V. Glebovsky ◽  
H. Fishmeister ◽  
J. Riedle ◽  
V. Semenov ◽  
P. Gumbsch
Keyword(s):  
Surface Energy ◽  
Crack Propagation ◽  
Single Crystals ◽  
Crack Front ◽  
Crystallographic Orientation ◽  
Cleavage Plane ◽  
Crack Plane ◽  
Experimental Procedure ◽  
Resist Crack Propagation

AbstractFor fracture studies on oriented W monocrystalline specimens it is necessary to produce very sharp, stopped precracks, which presents difficulties in the case of W. The experimental procedure and technique to produce precracks is described. The fracture experiments gave strong indications for a preference of the {100} plane as cleavage plane. It was found that the {110} planes successfully resist crack propagation, although they are the planes with the lowest surface energy. The appearance of the {121} plane as a cleavage plane in our experiments makes further studies with oriented W monocrystalline samples necessary.

Shape and energies of a dynamically propagating crack under bending

2003 ◽  
Vol 18 (10) ◽  
pp. 2379-2386 ◽  
Author(s):  
Dov Sherman ◽  
Ilan Be'ery
Keyword(s):  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Crack Front ◽  
Three Dimensional ◽  
Strain Energy Release ◽  
Governing Parameter ◽  
Propagating Crack ◽  
Front Shape

We report on the exact shape of a propagating crack in a plate with a high width/thickness ratio and subjected to bending deformation. Fracture tests were carried out with brittle solids—single crystal, polycrystalline, and amorphous. The shape of the propagating crack was determined from direct temporal crack length measurements and from the surface perturbations generated during rapid crack propagation. The shape of the crack profile was shown to be quarter-elliptical with a straight, long tail; the governing parameter of the ellipse axes is the specimen's thickness at most length of crack propagation. Universality of the crack front shape is demonstrated. The continuum mechanics approach applicable to two-dimensional problems was used in this three-dimensional problem to calculate the quasistatic strain energy release rate of the propagating crack using the formulations of the dynamic energy release rate along the crack loci. Knowledge of the crack front shape in the current geometry and loading configuration is important for practical and scientific aspects.

A New Stress-Intensity Factor Solution for an External Surface Crack in Spheres

2021 ◽  
Author(s):  
James C. Sobotka ◽  
Yi-Der Lee ◽  
Joseph W. Cardinal ◽  
R. Craig McClung
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Crack Front ◽  
Surface Crack ◽  
Degrees Of Freedom ◽  
External Surface ◽  
Crack Plane ◽  
Finite Element Analyses ◽  
Stress Variations ◽  
Geometric Formulation

Abstract This paper describes a new stress-intensity factor (SIF) solution for an external surface crack in a sphere that expands capabilities previously available for this common pressure vessel geometry. The SIF solution employs the weight function (WF) methodology that enables rapid calculations of SIF values. The WF methodology determines SIF values from the nonlinear stress variations computed for the uncracked geometry, e.g., from service stresses and/or residual stresses. The current approach supports two degrees of freedom that denote the two crack tips located normal to the surface and the surface of the sphere. The geometric formulation of this solution enforces an elliptical crack front, maintains normality of the crack front with the free surface, and supports two degrees of freedom for fatigue crack growth from an internal crack tip and a surface crack tip. The new SIF solution accommodates spherical geometries with an exterior diameter greater than or equal to four times the thickness. This WF SIF solution has been combined with stress variations common for spherical pressure vessels: uniform internal pressure on the interior surface, uniform tension on the crack plane, and uniform bending on the crack plane. This paper provides a complete overview of this solution. We present for the first time the geometric formulation of the crack front that enables the new functionality and set the geometric limits of the solution, e.g., the maximum size and shape of the crack front. The paper discusses the bivariant WF formulation used to define the SIF solution and details the finite element analyses employed to calibrate terms in the WF formulation. A summary of preliminary verification efforts demonstrates the credibility of this solution against independent results from finite element analyses. We also compare results of this new solution against independent SIFs computed by finite element analyses, legacy SIF solutions, API 579, and FITNET. These comparisons indicate that the new WF solution compares favorably with results from finite element analyses. This paper summarizes ongoing efforts to improve and extend this solution, including formal verification and development of an internal surface crack model. Finally, we discuss the capabilities of this solution’s implementation in NASGRO® v10.0.

scholarly journals Crack Propagation Characteristics and Fracture Surface Energy of Boride Cermets

2002 ◽  
Vol 66 (11) ◽  
pp. 1116-1121
Author(s):  
Hiromoto Kitahara ◽  
Yasuhiro Yoshikawa ◽  
Fuyuki Yoshida ◽  
Hideharu Nakashima ◽  
Kazuo Hamashima ◽  
...  
Keyword(s):  
Fracture Surface ◽  
Surface Energy ◽  
Crack Propagation ◽  
Propagation Characteristics ◽  
Fracture Surface Energy

Microhardness anisotropy on the (010) cleavage plane of single crystals of Bi2S3 and Sb2S3

1992 ◽  
Vol 27 (5) ◽  
pp. 1357-1360 ◽  
Author(s):  
Hong Li ◽  
M. Jensen ◽  
R. C. Bradt
Keyword(s):  
Single Crystals ◽  
Cleavage Plane
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