Crack tip plastic zone under Mode I, Mode II and mixed mode (I+II) conditions

2010 ◽  
Vol 36 (5) ◽  
pp. 575-598 ◽  
Author(s):  
M.R. Ayatollahi ◽  
Karo Sedighiani
Keyword(s):  
Plastic Zone ◽  
Mixed Mode ◽  
Crack Tip ◽  
Mode I ◽  
Mode Ii

Mixed Mode Interface Toughness Of Metal / Ceramic Joints

1995 ◽  
Vol 409 ◽  
Author(s):  
Yueguang Wei ◽  
John W. Hutchinson
Keyword(s):  
Mixed Mode ◽  
Metal Layer ◽  
Crack Tip ◽  
Crack Advance ◽  
Mode I ◽  
Mode Ii ◽  
Elastic Strip ◽  
Interface Toughness ◽  
Metal Ceramic ◽  
Work Of Fracture

AbstractA mechanics study of the interface toughness of joints comprised of ceramic substrates joined by a thin ductile metal layer is carried out for arbitrary combinations of mode I and mode II loading. The crack lies on one of the metal/ceramic interfaces, and the mechanism of separation at the crack tip is assumed to be atomic decohesion. The SSV model proposed by Suo, Shih and Varias is invoked. This model employs a very narrow elastic strip imposed between the substrate and the ductile layer to model the expected higher hardness of material subject to high strain gradients and possible dislocation-free zone in the immediate vicinity of the crack tip. The criterion for crack advance is the requirement that energy release rate at the crack tip in this narrow elastic strip be the atomistic work of fracture. The contribution of plastic dissipation in the metal layer to the total work of fracture is computed as a function of the thickness and yield strength of the layer and of the relative amount of mode II to mode I. Ductile joints display exceptionally strong thickness and mixed mode dependencies.

The Effect of T-Stress on Crack-Tip Plastic Zones Under Cyclic Mixed-Mode Loading Conditions

2013 ◽  
Author(s):  
Qays Nazarali ◽  
Xin Wang
Keyword(s):  
Stress Intensity ◽  
Cyclic Loading ◽  
Stress Field ◽  
Plastic Zone ◽  
Mixed Mode ◽  
Crack Tip ◽  
Mode I ◽  
Loading Conditions ◽  
T Stress ◽  
Plastic Zones

In this paper, the influence of T-stress on crack-tip plastic zones under mixed-mode I and II loading conditions under cyclic loading is examined. The crack-tip stress field is defined in terms of the ranges of mixed-mode stress intensity factors and the T-stress using William’s series expansion. The crack-tip stress field is incorporated into the Von Mises yield criteria to develop an expression that determines the cyclic crack-tip plastic zone. Using the resultant expression, the cyclic plastic zone is obtained for various combinations of mode II to mode I stress intensity factor ratios and levels of T-stress. For the purpose of demonstrating the significance of the T-stress, this paper further analyses the plastic zone size for center cracked plate (CCP) specimen subjected to bi-axial mixed-mode cyclic loading.

scholarly journals Fatigue Crack Growth under Non-Proportional Mixed Mode Loading in Rail and Wheel Steel Part 1: Sequential Mode I and Mode II Loading

2019 ◽  
Vol 9 (10) ◽  
pp. 2006 ◽  
Author(s):  
Makoto Akama
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Mixed Mode ◽  
Crack Tip ◽  
Wheel Steel ◽  
Mode I ◽  
Mode Ii ◽  
Mode Ii Loading ◽  
Crack Growth Rates ◽  
Branch Crack

Fatigue tests were performed to estimate the coplanar and branch crack growth rates on rail and wheel steel under non-proportional mixed mode I/II loading cycles simulating the load on rolling contact fatigue cracks; sequential and overlapping mode I and II loadings were applied to single cracks in the specimens. Long coplanar cracks were produced under certain loading conditions. The fracture surfaces observed by scanning electron microscopy and the finite element analysis results suggested that the growth was driven mainly by in-plane shear mode (i.e., mode II) loading. Crack branching likely occurred when the degree of overlap between these mode cycles increased, indicating that such degree enhancement leads to a relative increase of the maximum tangential stress range, based on an elasto–plastic stress field along the branch direction, compared to the maximum shear stress. Moreover, the crack growth rate decreased when the material strength increased because this made the crack tip displacements smaller. The branch crack growth rates could not be represented by a single crack growth law since the plastic zone size ahead of the crack tip increased with the shear part of the loading due to the T-stress, resulting in higher growth rates.

Asymptotic Crack-Tip Fields for Perfectly Plastic Solids Under Plane-Stress and Mixed-Mode Loading Conditions

1990 ◽  
Vol 57 (3) ◽  
pp. 635-638 ◽  
Author(s):  
P. Dong ◽  
J. Pan
Keyword(s):  
Plane Stress ◽  
Mixed Mode ◽  
Crack Tip ◽  
Mode I ◽  
Mode Ii ◽  
Crack Tip Field ◽  
Crack Tip Fields ◽  
Perfectly Plastic ◽  
Mixed Mode Crack ◽  
Small Constant

In this paper, we first discuss some of the properties of the crack-tip sectors for perfectly plastic materials under plane-stress conditions. Then starting with the plane-stress mixed-mode crack-tip fields suggested by Shih (1973), we assemble these sectors in a slightly different manner from those in Shih (1973). The missing governing equations needed to completely specify the crack-tip fields for both near mode I and near mode II mixed-mode loadings are derived. The mode I crack-tip field, as the limit of the near mode I cases, differs from Hutchinson’s solution (1968) by the appearance of a small constant stress sector ahead of the crack tip. In addition, the relevance of the solutions of the near mode II cases to some interesting features of the mixed-mode crack-tip fields, as suggested by Budiansky and Rice (1973), is also discussed.

Atomistic Study of Cleavage and Dislocation Emission in NiAl

1994 ◽  
Vol 364 ◽  
Author(s):  
M. Ludwig ◽  
P. Gumbsch
Keyword(s):  
Finite Element ◽  
Mixed Mode ◽  
Crack Tip ◽  
Mode I ◽  
Crack Plane ◽  
Dislocation Emission ◽  
Dislocation Generation ◽  
Embedded Atom ◽  
Atomistic Study ◽  
Eam Potential

AbstractThe atomistic processes during fracture of NiAl are studied using a new embedded atom (EAM) potential to describe the region near the crack tip. To provide the atomistically modeled crack tip region with realistic boundary conditions, a coupled finite element - atomistic (FEAt) technique [1] is employed. In agreement with experimental observations, perfectly brittle cleavage is observed for the (110) crack plane. In contrast, cracks on the (100) plane either follow a zig-zag path on (110) planes, or emit dislocations. Dislocation generation is studied in more detail under mixed mode I/II loading conditions.

scholarly journals Mixed-Mode Interlaminar Fracture Toughness of Glass and Carbon Fibre Powder Epoxy Composites—For Design of Wind and Tidal Turbine Blades

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2103
Author(s):  
Christophe Floreani ◽  
Colin Robert ◽  
Parvez Alam ◽  
Peter Davies ◽  
Conchúr M. Ó. Brádaigh
Keyword(s):  
Fracture Toughness ◽  
Carbon Fibre ◽  
Composite Structures ◽  
Mixed Mode ◽  
Epoxy Composites ◽  
Mode I ◽  
Mode Ii ◽  
Pure Mode ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture

Powder epoxy composites have several advantages for the processing of large composite structures, including low exotherm, viscosity and material cost, as well as the ability to carry out separate melting and curing operations. This work studies the mode I and mixed-mode toughness, as well as the in-plane mechanical properties of unidirectional stitched glass and carbon fibre reinforced powder epoxy composites. The interlaminar fracture toughness is studied in pure mode I by performing Double Cantilever Beam tests and at 25% mode II, 50% mode II and 75% mode II by performing Mixed Mode Bending testing according to the ASTM D5528-13 test standard. The tensile and compressive properties are comparable to that of standard epoxy composites but both the mode I and mixed-mode toughness are shown to be significantly higher than that of other epoxy composites, even when comparing to toughened epoxies. The mixed-mode critical strain energy release rate as a function of the delamination mode ratio is also provided. This paper highlights the potential for powder epoxy composites in the manufacturing of structures where there is a risk of delamination.

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