ICF4 discussion: ?Elastic/plastic separation energy rate for crack advance in finite growth steps,? by A. P. Kfouri and J. R. Rice ICF4 discussion: ?A contribution to the analysis of quasi static crack growth in sheet materials,? by A. U. de Koning

1977 ◽  
Vol 13 (5) ◽  
pp. 728-731 ◽  
Author(s):  
H. F�hring ◽  
T. Seeger
1996 ◽  
Vol 63 (1) ◽  
pp. 204-209 ◽  
Author(s):  
S. Omprakash ◽  
R. Narasimhan

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.


CORROSION ◽  
10.5006/3572 ◽  
2021 ◽  
Author(s):  
Ramgopal Thodla ◽  
Anand Venkatesh

Fatigue crack growth rate was developed on three heats of alloy 718 (UNS N07718) under cathodic polarization, over a wide range of loading conditions. Fatigue crack growth rate increased with decreasing frequency over a range of Kmax and K conditions. In most cases, there was no evidence of a plateau in fatigue crack growth rate at low frequencies. The fatigue crack growth rate over the range of conditions evaluated were influenced by static crack growth rate at Kmax. The principle of superposition of fatigue crack growth and static crack growth was used to rationalize the observed crack growth rate response. Static crack growth rate of alloy 718 measured under constant K conditions, was lower than that measured under rising displacement conditions. A crack tip strain rate based model was used to rationalize the fatigue crack growth rate behavior and the static crack growth rate behavior under constant K. However, the formulation of the model for the rising K was not able to rationalize the crack growth rate under rising displacement conditions.


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