Paper Title:
New Insights into Plasticity-Induced Crack Tip Shielding via Mathematical Modelling and Full Field Photoelasticity

The topic of plasticity-induced closure and its role in shielding a crack tip from the full range of applied stress intensity factor has provoked considerable controversy over several decades. We are now in an era when full field measurement techniques, e.g. thermoelasticity and photoelasticity, offer a means of directly obtaining the stress field around a crack tip and hence the effective stress intensity factor. Nonetheless, without a clear understanding of the manner in which the development of plasticity around a growing crack affects the applied stress field, it will remain difficult to make crack growth rate predictions except through the use of an often highly conservative upper bound growth rate curve where closure is absent, or through semi-empirical approaches. This paper presents new evidence for an interpretation of plasticity-induced crack tip shielding as arising from two separate effects; a compatibility-induced interfacial shear stress at the elastic-plastic interface along the plastic wake of the crack, and a crack surface contact stress which will vary considerably as a function of stress state, load and material properties.

Key Engineering Materials (Volumes 345-346)
Edited by
S.W. Nam, Y.W. Chang, S.B. Lee and N.J. Kim
K.F. Tee, C.J. Christopher, M.N. James, E. A. Patterson, "New Insights into Plasticity-Induced Crack Tip Shielding via Mathematical Modelling and Full Field Photoelasticity ", Key Engineering Materials, Vols. 345-346, pp. 199-204, 2007
Online since
August 2007
Authors: Li Yun Li, F.X. Che, D.A. Liu
Abstract:Multi-crack problems are deeply involved in rock-like material and rock engineering. In order to study the influences of lateral stress and...
Authors: Jun Si, Fu Zhen Xuan, Shan Tung Tu
Abstract:The interaction behavior of two non-aligned through-wall cracks in flat plates is investigated by the finite element method (FEM) under...
Authors: Jia Zhen Zhang, Xiao Dong He, Shan Yi Du
Abstract:In-situ SEM observations have revealed that fatigue crack propagation in aluminium alloys is caused by the shear band decohesion around the...
Authors: Jaroslav Pokluda, Yoshiyuki Kondo, Karel Slámečka, Pavel Šandera, Jana Horníková
Abstract:Asymmetric arrangements of stored crack-wake dislocations and low values of the size ratio SR, the plastic zone size / the characteristic...
Authors: Stanislav Seitl, Pavel Hutař, Zdeněk Knésl
Abstract:The formulations of fatigue crack growth prediction are still mostly based on phenomenological models. A commonly used formula in the field...