Multi-Parameter Fracture Mechanics: Crack Approaching a Bi-Material Interface

2018 ◽  
Vol 784 ◽  
pp. 79-84
Author(s):  
Lucie Malíková ◽  
Jan Klusák
Keyword(s):  
Tangential Stress ◽  
Initial Crack ◽  
The Finite Element Method ◽  
Material Interface ◽  
Stress Criterion ◽  
Three Point Bending ◽  
Maximum Tangential Stress Criterion ◽  
Higher Order Terms ◽  
Elastic Mismatch ◽  
Crack Propagation Angle

Fracture behaviour of a crack approaching a bi-material interface is investigated. A three-point bending configuration of a cracked specimen is simulated numerically by means of the finite element method and the interaction between the crack and aggregate is studied. The crack deflection angle is estimated by means of the maximum tangential stress criterion in its classical as well as generalized (multi-parameter) form considering the Williams’ power series with various numbers of the higher-order terms for the tangential stress approximation. The influence of the elastic mismatch and of other parameters on the calculated initial crack propagation angle is discussed.

Application of Multi-Parameter Fracture Mechanics to Study of Crack Propagation Angle in Selected Mixed-Mode Geometry

2013 ◽  
Vol 592-593 ◽  
pp. 209-212 ◽  
Author(s):  
Lucie Šestáková Malíková ◽  
Václav Veselý
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Mixed Mode ◽  
Initial Crack ◽  
Propagation Angle ◽  
Linear Elastic ◽  
Higher Order Terms ◽  
Elastic Fracture ◽  
Cracked Specimens ◽  
Crack Propagation Angle

The multi-parameter fracture mechanics becomes more and more significant, because it is shown that it can help to describe fracture processes occurring in cracked specimens more precisely than conventional linear elastic fracture mechanics. In this paper, the concept based on the Williams expansion derived for approximation of stress/displacement crack-tip fields is presented and applied on a mixed-mode configuration. Two fracture criteria for estimation of the initial crack propagation angle are introduced. A parametric study is performed in order to investigate the dependence of the crack propagation angle on the stress intensity factors ratio. Influence and importance of taking into account the so-called higher-order terms of the Williams expansion are discussed and some recommendations are stated.

Application of the Williams Expansion near a Bi-Material Interface

2017 ◽  
Vol 754 ◽  
pp. 206-209 ◽  
Author(s):  
Lucie Malíková ◽  
Stanislav Seitl
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Tip ◽  
Higher Order ◽  
Simplified Model ◽  
The Finite Element Method ◽  
Material Interface ◽  
Higher Order Terms ◽  
Element Method ◽  
Crack Tip Stress

A simplified model of a crack approaching a bi-material interface is modelled by means of the finite element method in order to investigate the significance of the higher-order terms of the Williams expansion for the proper approximation of the opening crack-tip stress near the bi-material interface. The discussion on results is presented and the importance of the higher-order terms proved.

Evaluation of size effect on mixed-mode fracture behavior of epoxy/silica nanocomposites

2017 ◽  
Vol 52 (4) ◽  
pp. 239-248 ◽  
Author(s):  
Ahmad Ghasemi-Ghalebahman ◽  
Javad Akbardoost ◽  
Yaser Ghaffari
Keyword(s):  
Fracture Toughness ◽  
Tangential Stress ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Process Zone ◽  
Maximum Tangential Stress ◽  
Mixed Mode Fracture ◽  
Mode Fracture ◽  
Stress Criterion ◽  
Maximum Tangential Stress Criterion

The aim of this study was to examine the effect of size on the mixed-mode fracture toughness of quasi-brittle nanocomposites with the help of modified maximum tangential stress criterion. The literature reveals that the effect of size on mixed-mode fracture behavior of brittle nanocomposites has not been well investigated previously using modified maximum tangential stress criterion. The studied nanocomposites were made of epoxy resin reinforced with 7 wt%, 20–30 nm nanosilica. The accuracy of the method was assessed by taking into account the high-order terms of Williams series expansion along with finite element over-deterministic method. To investigate the effect of size on fracture toughness, a number of three-point semi-circular bending tests with different radii and four angles of edge–crack orientation were conducted and subjected to mixed-mode loading. The size of fracture process zone and apparent fracture toughness ( Kc) were also evaluated as a function of sample size. Experimental results showed that the proposed approach can accurately predict the fracture behavior of studied nanocomposites.

The Influence of Loading Ratio on Fatigue Crack Propagation Through a Bi-Material Interface

2007 ◽  
Vol 348-349 ◽  
pp. 317-320
Author(s):  
Luboš Náhlík ◽  
Pavel Hutař ◽  
Zdeněk Knésl
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Threshold Values ◽  
The Finite Element Method ◽  
Material Interface ◽  
Applied Loading ◽  
Loading Ratio ◽  
Elastic Mismatch ◽  
Plasticity Induced Crack Closure

The paper is devoted to fatigue crack propagation in layered materials. The influence of plasticity induced crack closure on threshold values for fatigue crack propagation through interfaces between different materials layers is studied. The main aim was to estimate the influence of the loading ratio R on threshold values for crack propagation through a bi-material interface as a function of the elastic mismatch of both materials. The finite element method (FEM) is used for numerical calculations. Results obtained for different loading ratios, materials, boundary conditions and magnitude of applied loading can be generalized and used for the design of composite bodies with different material layers.

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