Effect of error in crack tip identification on the photoelastic evaluation of SIFs of interface cracks

2009 ◽  
Author(s):  
B. Neethi Simon ◽  
K Ramesh
Keyword(s):  
Crack Tip ◽  
Interface Cracks

Mixed Mode Loading of an Interface Crack Subjected to Creep Conditions

2003 ◽  
Author(s):  
Ali P. Gordon ◽  
David L. McDowell
Keyword(s):  
Transition Layer ◽  
Mixed Mode ◽  
Elevated Temperatures ◽  
Numerical Solutions ◽  
Crack Tip ◽  
Functionally Graded ◽  
Pure Mode ◽  
Mixed Mode Loading ◽  
Creep Ductility ◽  
Interface Cracks

Interface cracks are seldom subjected to pure Mode I or pure Mode II conditions. Stationary interface cracks between two distinct, bonded elastic-creep materials subjected to remotely applied mixed mode loading are simulated. The finite element method (FEM) is used to examine crack tip fields and candidate driving force parameters for crack growth. Plane strain conditions are assumed. In most cases a functionally graded transition layer is included between the two materials. Examples of such systems include weld metal (WM) and base metal (BM) interfaces in welded or repaired boiler components subjected to elevated temperatures. Numerical solutions based on the asymptotic fields of the homogeneous and heterogeneous Arcan-type specimens are presented. Creep ductility-based damage models are used to predict the initial crack propagation trajectory. The incorporation of functionally graded transition layer regions affects the evolution of time-dependent stress components in the vicinity of the crack tip. The magnitude and direction of crack tip propagation can then be optimized with respect to interface properties.

scholarly journals On stationary and moving interface cracks with frictionless contact in anisotropic bimaterials

1993 ◽  
Vol 443 (1919) ◽  
pp. 563-572
Keyword(s):  
Crack Problem ◽  
Stress Singularity ◽  
Crack Tip ◽  
Substantial Part ◽  
Open Crack ◽  
Interface Cracks ◽  
Complete Representation ◽  
Crack Tip Fields ◽  
Out Of Plane ◽  
Anisotropic Bimaterials

The asymptotic structure of near-tip fields around stationary and steadily growing interface cracks, with frictionless crack surface contact, and in anisotropic bimaterials, is analysed with the method of analytic continuation, and a complete representation of the asymptotic fields is obtained in terms of arbitrary entire functions. It is shown that when the symmetry, if any, and orientation of the anisotropic bimaterial is such that the in-plane and out-of-plane deformations can be separated from each other, the in-plane crack-tip fields will have a non-oscillatory, inverse-squared-root type stress singularity, with angular variations clearly resembling those for a classical mode II problem when the bimaterial is orthotropic. However, when the two types of deformations are not separable, it is found that an oscillatory singularity different than that of the counterpart open-crack problem may exist at the crack tip for the now coupled in-plane and out-of-plane deformation. In general, a substantial part of the non-singular higher-order terms of the crack-tip fields will have forms that are identical to those for the counterpart open-crack problem, which give rise to fully continuous displacement components and zero tractions along the crack surfaces as well as the material interface.

The r−1/2 (ln r) Singularities at Interface Cracks in Monoclinic and Isotropic Bimaterials due to Heat Flow

1993 ◽  
Vol 60 (2) ◽  
pp. 432-437 ◽  
Author(s):  
G. Yan ◽  
T. C. T. Ting
Keyword(s):  
Heat Flow ◽  
Interface Crack ◽  
Simple Form ◽  
Crack Tip ◽  
Higher Order ◽  
Stress Singularities ◽  
Interface Cracks ◽  
Existence Conditions

It is known that the stress singularities at an interface crack tip of bimaterials with the effects of heat flow may have the form r−1/2 (ln r). The existence conditions of the higher order singularitiy r−1/2 (ln r) are studied for monoclinic bimaterials whose plane of symmetry is at x3 = 0. It is shown that the higher order singularity does not exist if the bimaterial is mismatched. If the bimaterial is non-mismatched, the higher order singularity does not exist when a certain condition is satisfied. This condition is given explicitly for monoclinic bimaterials with the plane of symmetry of x3 = 0 and in a simple form for isotropic bimaterials.

Finite Element Analysis of Interface Cracks Using Multiple Point Constraints

2006 ◽  
Vol 41 (4) ◽  
pp. 311-321
Author(s):  
C H Liu ◽  
Jui-Hsiang Lin
Keyword(s):  
Finite Element ◽  
Crack Tip ◽  
Multiple Point ◽  
Element Analysis ◽  
Interface Cracks ◽  
Closed Mode ◽  
Nodal Displacements ◽  
Element Technique ◽  
Stress Boundary Conditions ◽  
Virtual Crack Extension Method

A finite element technique to analyse closed-mode interface cracks is proposed in this study. Stress boundary conditions for a closed-tip model are transformed into multiple point constraints (MPCs) for nodal displacements. These constraints are imposed upon the finite element solutions to simulate closed-tip stress fields in crack-tip elements. This technique can deal with small as well as large crack-tip contact zones, and no special elements other than the standard quarter-point elements are needed. Since stresses approach infinity at the crack tip in a quarter-point element, dominant terms are used in deriving MPCs for nodal displacements. Fracture parameters are obtained by using the virtual crack extension method, and numerical results are in good agreement with analytical results.

Stress Intensity Factor of a Central Interface Crack in a Bonded Strip under Arbitrary Material Combination

2011 ◽  
Vol 462-463 ◽  
pp. 1146-1151
Author(s):  
Naoaki Noda ◽  
Yu Zhang ◽  
Xin Lan ◽  
Kentaro Takaishi
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Interface Crack ◽  
Crack Tip ◽  
Material Combination ◽  
Interface Cracks ◽  
Axial Tension ◽  
Crack Problems ◽  
Previously Treated

Although a lot of interface crack problems were previously treated, few solutions are available under arbitrary material combination. This paper deals with one central interface crack and numerical interface cracks in a bonded strip. Then, the effects of material combination on the stress intensity factors are discussed. A useful method to calculate the stress intensity factor of interface crack is presented with focusing on the stress at the crack tip calculated by the finite element method. For one central interface crack, it is found that the results of bonded strip under remote uni-axial tension are always depending on the Dunders’ parameters , and different from the well-known solution of the central interface crack under internal pressure that is only depending on . Besides, it is shown that the stress intensity factor of bonded strip can be estimated from the stress of crack tip in the bonded plate when there is no crack. It is also found that when , when , and when . For numerical interface cracks , values of and with arbitrary material combination expressed by , are obtained.

Analysis of the bi-material interface cracks based on configurational forces

2021 ◽  
pp. 1-23
Author(s):  
Ran Liu ◽  
Qun Li
Keyword(s):  
Interface Crack ◽  
Fracture Criterion ◽  
Crack Problem ◽  
Elastic Strain Energy ◽  
Crack Tip ◽  
Configurational Forces ◽  
Interface Fracture ◽  
Loading Conditions ◽  
Interface Cracks ◽  
Wide Range

Abstract In this paper, an innovative interface fracture criterion is proposed based on the concept of configurational forces in material space. In this criterion, the crack tip configurational forces as driving force is introduced to describe the interface crack evolution under mixed mode loading conditions. And it assumes that the interface crack propagates due to the competition of resultant of configurational forces with interface fracture toughness. The analytical expression of the configurational forces are obtained by differentiating the elastic strain energy density and conservative integral for interface cracks. And the relation of interface crack tip configurational forces with classical complex intensity factors are obtained through strict mathematical deduction. The interface crack tip configurational forces are evaluated for a classic interface crack problem covering a wide range of bi-material oscillation index. The configurational forces based interface fracture criterion is validated through series interface fracture experiments. The proposed criterion may provide a novel framework for analysis of interface fracture under complex loading conditions.

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