Asymptotic analysis of mode I propagating crack-tip field in a creeping material

2003 ◽  
Vol 2 (1) ◽  
pp. 76-81
Author(s):  
Zhen-qing Wang ◽  
Qi-cheng Zhao ◽  
Wen-yan Liang ◽  
Zhang-jian Fu
Keyword(s):  
Asymptotic Analysis ◽  
Crack Tip ◽  
Mode I ◽  
Crack Tip Field ◽  
Propagating Crack

Asymptotic Field near the Tip of a Mode I Quasi-Statically Propagating Crack in Rate-Sensitive Materials

2010 ◽  
Vol 452-453 ◽  
pp. 141-144
Author(s):  
Jia Lei Li ◽  
Bin Jia ◽  
Zhen Qing Wang ◽  
Bao Jun Pang
Keyword(s):  
Power Law ◽  
Crack Tip ◽  
Viscosity Coefficient ◽  
Mode I ◽  
Crack Tip Field ◽  
Plane Stress Condition ◽  
Propagating Crack ◽  
Power Law Function ◽  
Constitutive Mode ◽  
Hardening Coefficient

An elastic-viscoplastic constitutive mode was adopted to analyze asymptotically the tip field of a mode I quasi-statically propagating crack in rate-sensitive materials under plane stress condition. Under the assumption that the viscosity coefficient is a power law function of the rate of effective plastic strain, it was obtained through dimension match that the crack tip field possesses power law singularity. And the singularity exponent is uniquely determined by the power law exponent in the supposed viscosity coefficient. The elasticity, plasticity and viscosity of material at crack-tip only can be matched reasonably under linear-hardening condition. Variations of crack tip field characters according to each material parameter were discussed by means of numerical computation. The stress intensity is dominated by the material viscosity whereas the hardening coefficient has less significant influence on tip field. Furthermore, the solution can be transformed to the elastic-nonlinear-viscous one of Hui and Riedel if the limit case of zero hardening coefficient is considered.

scholarly journals An approach to analysis of dynamic crack growth at bimaterial interface

2009 ◽  
Vol 36 (4) ◽  
pp. 299-327 ◽  
Author(s):  
R. Nikolic ◽  
Jelena Djokovic
Keyword(s):  
Asymptotic Analysis ◽  
Strain Field ◽  
Crack Tip ◽  
Optical Data ◽  
Bimaterial Interface ◽  
Dynamic Crack ◽  
New Approach ◽  
Shear Wave Speed ◽  
Propagating Crack

In this paper is presented the new approach to asymptotic analysis of the stress and strain fields around a crack tip that is propagating dynamically along a bimaterial interface. Through asymptotic analysis the problem is being reduced to solving the Riemann-Hilbert's problem, what yields the strain potential that is used for determination of the strain field around a crack tip. The considered field is that of a dynamically propagating crack with a speed that is between zero and shear wave speed of the less stiffer of the two materials, bound along the interface. Using the new approach in asymptotic analysis of the strain field around a tip of a dynamically propagating crack and possibilities offered by the Mathematica programming package, the results are obtained that are compared to both experimental and numerical results on the dynamic interfacial fracture known from the literature. This comparison showed that it is necessary to apply the complete expression obtained by asymptotic analysis of optical data and not only its first term as it was done in previous analyses.

The Asymptotic Elastic-Viscoplastic Field at Mode I Dynamic Propagating Crack-Tip

2007 ◽  
Vol 348-349 ◽  
pp. 817-820
Author(s):  
Zhen Qing Wang ◽  
Ji Bin Wang ◽  
Wen Yan Liang ◽  
Juan Su
Keyword(s):  
Crack Tip ◽  
Viscosity Coefficient ◽  
Plastic Strain Rate ◽  
Mode I ◽  
Mode I Crack ◽  
Moving Crack ◽  
Dynamic Propagating ◽  
Propagating Crack ◽  
Hardening Condition ◽  
Elastic Unloading

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.

On the Extent of Dominance of Asymptotic Elastodynamic Crack-Tip Fields: Part II—Numerical Investigation of Three-Dimensional and Transient Effects

1991 ◽  
Vol 58 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Sridhav Krishnaswamy ◽  
Ares J. Rosakis ◽  
G. Ravichandran
Keyword(s):  
Three Dimensional ◽  
Crack Tip ◽  
Experimental Results ◽  
Mode I ◽  
Transient Effects ◽  
Adequate Description ◽  
Crack Tip Field ◽  
Drop Weight ◽  
The Impact ◽  
Laboratory Specimen

In Part I of this paper, the question of the extent of dominance of the mode I asymptotic elastodynamic crack-tip field (the KdI-field) was studied experimentally. Here, the results of two and three-dimensional elastodynamic finite element simulations of the drop-weight experiments are reported. The load records as obtained from the impact hammer and supports of the drop-weight loading device were used as boundary tractions in the numerical simulations. For the laboratory specimen studied, the results of the simulations indicate that the asymptotic elastodynamic field is not an adequate description of the actual fields prevailing over any sizeable region around the crack tip. This confirms the experimental results of Part I which showed that three-dimensional and transient effects necessarily have to be taken into account for valid interpretation of experimental results.

The Elastic-Viscoplastic Field at the Mixed-Mode Crack-Tip under Compression and Shear

2008 ◽  
Vol 385-387 ◽  
pp. 321-324
Author(s):  
Wen Yan Liang ◽  
Zhen Qing Wang ◽  
Bo Zhou ◽  
Hong Qing Lv
Keyword(s):  
Numerical Solution ◽  
Mixed Mode ◽  
Equivalent Plastic Strain ◽  
Crack Tip ◽  
Viscosity Coefficient ◽  
Plastic Strain Rate ◽  
Crack Tip Field ◽  
Viscosity Effect ◽  
Mixed Mode Crack ◽  
Propagating Crack

Under the assumption that the viscosity coefficient is in inverse proportion to the power law of the equivalent plastic strain rate. The friction touch effect between viscosity and crack-tip surfaces is considered, the asymptotic solution is established for elastic-viscoplastic field at the mixed-mode quasi static crack-tip under compression and shear. The numerical solution at crack-tip without stress and stain gap is obtained. The variation of numerical solution is discussed for the mixed-mode under compression and shear according to each parameter. Through numerical results and analysis for the mixed-mode crack-tip field under compressing and shear, it is whole plastic without elastic unloaded section, viscosity effect is an important factor when propagating crack-tip field.

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