Automatic crack growth tracking of bimaterial interface cracks

1988 ◽  
Vol 37 (2) ◽  
pp. 123-135
Author(s):  
Nabil A. B. Yehia ◽  
Mark S. Shephard
Keyword(s):  
Crack Growth ◽  
Bimaterial Interface ◽  
Interface Cracks

Diffusive Crack Growth at a Bimaterial Interface

1996 ◽  
Vol 63 (3) ◽  
pp. 796-803 ◽  
Author(s):  
Tze-jer Chuang ◽  
June-Liang Chu ◽  
Sanboh Lee
Keyword(s):  
Tensile Stress ◽  
Crack Growth ◽  
Crack Tip ◽  
Ceramic Composites ◽  
Bimaterial Interface ◽  
Self Diffusion ◽  
Interfacial Sliding ◽  
Stress Solution ◽  
Microcrack Growth ◽  
Loading Parameter

The high temperature microcrack growth behavior along a planar interface between two elastic dissimilar media is investigated with an aim at estimating service life of advanced ceramic composites under creep-rupture conditions. The crack is assumed to grow along the interface normal to a remote applied tensile stress via a coupled surface and grain-boundary diffusion under steady-state creep conditions. The crack-tip conditions were first derived from the asymmetric tip morphology developed by surface self-diffusion. The governing integro-differential equation containing the unknown tensile stress distribution along the interface ahead of the moving crack tip was derived and it was found that a new length parameter exists as a scaling factor for the interface for which the solution becomes identical to that of the single-phase media when plotted on the nondimensional physical plane. In contrast to the elastic stress solution which shows singularity at the tip and oscillatory character away from the tip, the creep stresses have a peak value away from the tip due to a wedging effect and interfacial sliding eliminates stress oscillation resulting in a decoupling between mode I and mode II stress fields. This stress solution ties the far-field loading parameter to the crack-tip conditions in terms of the unknown crack velocity to give a specific V-K functional relationship. It was shown that a stress exponent of 12 in the conventional power-law crack growth emerges at higher applied stress levels. An analysis on energy balance shows that the energy release during crack growth amounts to the J-integral which derives mostly from work done by “wedging,” not from strain energy loss. A constraint on interfacial diffusivities of the two species was found and its implications on possible microstructural developments were discussed.

A Finite Element Analysis of Mode III Quasi-Static Crack Growth at a Ductile-Brittle Interface

1996 ◽  
Vol 63 (1) ◽  
pp. 204-209 ◽  
Author(s):  
S. Omprakash ◽  
R. Narasimhan
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Power Law ◽  
Plastic Material ◽  
Bimaterial Interface ◽  
Mode Iii ◽  
Elastic Substrate ◽  
Elastic Plastic ◽  
Static Crack ◽  
Elastic Plastic Material

Steady-state quasi-static crack growth along a bimaterial interface is analyzed under Mode III, small-scale yielding conditions using a finite element procedure. The interface is formed by an elastic-plastic material and an elastic substrate. The top elastic-plastic material is assumed to obey the J2 incremental theory of plasticity. It undergoes isotropic hardening with either a bilinear uniaxial response or a power-law response. The results obtained from the full-field numerical analysis compare very well with the analytical asymptotic results obtained by Castan˜eda and Mataga (1991), which forms one of the first studies on this subject. The validity of the separable form for the asymptotic solution assumed in their analysis is investigated. The range of dominance of the asymptotic fields is examined. Field variations are obtained for a power-law hardening elastic-plastic material. It is seen that the stresses are lower for a stiffer substrate. The potential of the bimaterial system to sustain slow stable crack growth along the interface is studied. It is found that the above potential is larger if the elastic substrate is more rigid with respect to the elastic-plastic material.

Effect of a Graded Layer on the Dissipated Energy During Fatigue Crack Growth on Plastically Mismatched Interfaces Under Mixed-Mode Loading

2009 ◽  
Author(s):  
Craig M. Baudendistel ◽  
Nathan W. Klingbeil
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Mixed Mode ◽  
Dissipated Energy ◽  
Bimaterial Interface ◽  
Finite Element Models ◽  
Mixed Mode Loading ◽  
Plastic Properties ◽  
Plastic Dissipation

Recent work has proposed a dissipated energy theory of fatigue crack growth under mode I loading for homogenous materials and has since been extended to a bimaterial interface geometry under mixed-mode loading. An inherent assumption of this prior work is that a perfect crack exists along the interface joining the top and bottom layers. The current work extends the approach of previous studies to incorporate a grading of plastic properties between the two layers. The plastic dissipation is extracted from 2D parametric finite element models with ABAQUS. Results have shown that incorporation of a graded layer increass the overall amount of plastic dissipation between modes I and II, but is still bounded by the two cases where a minimum and maximum amount of plastic dissipation is accumulated. While the graded layer has a measurable effect, plastic dissipation is still dominated by the mode of loading.

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