Features of Dynamic Deformation of an Elastoviscoplastic Material in the Vicinity of a Moving Crack Tip

The viscosity of material is considered at propagating crack-tip. Under the assumption that the artificial viscosity coefficient is in inverse proportion to the power law of the plastic strain rate, an elastic-viscoplastic asymptotic analysis is carried out for moving crack-tip fields in power-hardening materials under plane-strain condition. A continuous solution is obtained containing no discontinuities. The variations of the numerical solution are discussed for mode I crack according to each parameter. It is shown that stress and strain both possess exponential singularity. The elasticity, plasticity and viscosity of material at the crack-tip only can be matched reasonably under linear-hardening condition. The tip field contains no elastic unloading zone for mode I crack.

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Dynamic stresses at a moving crack tip in a model of fracture propagation

Physical Review E ◽

10.1103/physreve.49.3382 ◽

1994 ◽

Vol 49 (4) ◽

pp. 3382-3388 ◽

Cited By ~ 33

Author(s):

Emily S. C. Ching

Keyword(s):

Fracture Propagation ◽

Crack Tip ◽

Moving Crack ◽

Dynamic Stresses

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Experimental Study on the Caustics of Moving Cracks and Elliptical Curvature under Impact Loading

Advances in Civil Engineering ◽

10.1155/2021/5524635 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Haohao Luo ◽

Renshu Yang ◽

Yanbing Wang ◽

Guoliang Yang ◽

Chengxiao Li ◽

...

Keyword(s):

Stress Intensity Factor ◽

Stress Intensity ◽

Intensity Factor ◽

Impact Loading ◽

Crack Tip ◽

Test System ◽

Moving Crack ◽

Linear Elastic ◽

Elastic Fracture ◽

Crack Tip Stress

A dynamic caustics test system was used, and different moving cracks were analysed to study the interaction between the crack growth rate, stress intensity factor, and curvature of the elliptical end of a moving crack under impact loading. Based on the linear elastic fracture mechanics theory, linearly fitting of the crack tip stress intensity factor and the elliptical curvature were employed to obtain the specific functional expressions. ABAQUS software was used to numerically simulate the moving crack fracture process passing through different elliptical curvatures. The crack tip stress intensity factor was calculated by the stress extrapolation method. The stress intensity factor obtained from the numerical calculation and the caustics test was consistent. The test and numerical simulation results showed that the direction of moving cracks entering and passing through the elliptical defects shows a certain regularity. As the ellipse curvature increased, the moving crack stress intensity factor passing through the ellipse gradually decreased, and the moving crack also passed easily through oval defects.

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Moving Crack in an Infinite Plate of Orthotropic Anisotropy FGMs under Anti-Plane Shear

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.97-101.928 ◽

2010 ◽

Vol 97-101 ◽

pp. 928-931

Author(s):

Xian Shun Bi ◽

Feng Yang ◽

Shuang Shuang Ma

Keyword(s):

Crack Velocity ◽

Characteristic Length ◽

Crack Problem ◽

Infinite Plate ◽

Crack Tip ◽

Shear Loading ◽

Local Theory ◽

Moving Crack ◽

Plane Shear ◽

Crack Tip Stress

The moving crack problem in an infinite plate of orthotropic anisotropy functionally graded materials (FGMs) subjected to an anti-plane shear loading is studied by making use of non- local theory. The shear modulus and mass density of FGMs are assumed to be of exponential form. Fourier transform is employed to solve the partial differential equation. The mixed boundary value problem is reduced to a pair dual integral equations which is solved by using Schmidt’s method. The semi-analytic solution of crack-tip stress is obtained, contrary to the classical elasticity solution, the crack-tip stress fields does not retains the stress singularity. The influences of the characteristic length, graded parameter, orthotropic coefficient and crack velocity on the crack-tip stress are analyzed. The numerical results show that the stress at the crack tip decrease as the characteristic length, crack velocity, graded parameter are increased and increase as the orthotropic coefficient is increased.

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In Situ Examination of moving Crack Tips in Ordered Intermetallics

MRS Proceedings ◽

10.1557/proc-539-29 ◽

1998 ◽

Vol 539 ◽

Author(s):

J.K. Heuer ◽

N.Q. Lam ◽

P.R. Okamoto ◽

J.F. Stubbins

Keyword(s):

Ion Irradiation ◽

High Stress ◽

Crack Tip ◽

Dark Field ◽

Stress Concentrations ◽

Moving Crack ◽

Dark Field Imaging ◽

Crack Tips ◽

Similarity And Difference

AbstractRecent studies have shown that high stress concentrations at moving crack tips in the intermetallic compound NiTi can induce a crystalline-to-amorphous (C-A) transformation of the crack tip region. This stress-induced C-A transformation has a temperature dependence and crystallization behavior similar to those of ion irradiation-induced C-A transformation of NiTi. The present study examines if these similarities between stress- and irradiation-induced amorphization hold true for two other intermetallic compounds, CuTi and Ni3Ti. In situ straining was performed in an intermediate-voltage transmission electron microscope. The presence or absence of an amorphous phase was determined by dark field imaging and selected area diffraction of crack tip regions. Crack tips in both CuTi and Ni3Ti were found to remain crystalline upon fracture. The observed absence of stress-induced amorphization in Ni3Ti is consistent with its known absence during irradiation, but the absence in CuTi differs from its known irradiation-induced amorphization behavior. Reasons for the similarity and difference are discussed.

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