Results 141 to 150 of about 12,651 (176)

Atomic-Scale Mechanism of Crack-Tip Plasticity: Dislocation Nucleation and Crack-Tip Shielding

Physical Review Letters, 1997
By isolating the process of dislocation emission from a crack tip under an applied tensile stress, we extract from a molecular dynamics simulation the atomic-level displacement and stress fields on the activated slip plane before and after the nucleation event.
Fabrizio Cleri, Sidney Yip, Dieter Wolf, Simon R. Phillpot   +3 more
openaire   +1 more source

Crack Tip Shielding from a Plastic ‘Inclusion’

Key Engineering Materials, 2011
This paper presents a very brief overview of the philosophy underlying a plastic inclusion approach to defining the boundary stresses imposed on the applied elastic stress or displacement field by the plastic deformation attendant on crack growth in a ductile material. It leads to two new fracture mechanics parameters, KR and KS.
M. Neil James, C.J. Christopher, Yan Wei Lu, K.F. Tee, Eann A Patterson   +4 more
openaire   +1 more source

Ultrasonic measurements of crack tip shielding by closure

Materials Science and Engineering: A, 1988
Abstract During fatigue, an existing crack closes partially owing to the compressive stresses set up by the deformed material. It is well established that this crack closure can have pronounced effects on the rate of crack propagation and thus on fatigue life.
O. Buck, R.B. Thompson, D.K. Rehbein
openaire   +1 more source

Crack tip shielding by micro-cracking in brittle solids

Acta Metallurgica, 1987
Abstract The effect of profuse micro-cracking at the tip of a macroscopic crack is studied with emphasis on the reduction in stress intensity, or shielding, within the micro-crack region. Shielding contributions arise from two consequences of micro-cracking, reduction in stiffness and release of residual stress. For the most part the study is limited
openaire   +1 more source

Fatigue crack growth and craze-induced crack tip shielding in polycarbonate

Polymer, 2012
Abstract This paper expounds a revised characterisation of the elastic stresses ahead of a crack tip in polycarbonate which takes account of the elastic–plastic boundary stresses induced by the presence of the crazed region that surrounds a crack.
M.N. James, C.J. Christopher, Y. Lu, E.A. Patterson   +3 more
openaire   +1 more source

Crack-Tip Shielding Effect on Fatigue Crack Propagation in Porous Silicon Carbide

Applied Mechanics and Materials, 2011
A sharply notched specimen of porous silicon carbide with porosity of 37% was fatigued under four-point bending. The opening displacement of a fatigue crack was measured at several positions along cracks by using scanning electron microscopy. The crack propagation curve was divided into stages I, II, and III.
Keisuke Tanaka, Yasuki Kita
openaire   +1 more source

Methods for crack opening load and crack tip shielding determination: a review

Fatigue & Fracture of Engineering Materials & Structures, 2003
ABSTRACTIn this paper a review of the literature on crack closure/opening load and crack tip shielding effects determination methods is presented. Commonly used ‘subjective’ (visual) and ‘non‐subjective’ approaches have been included. Procedures associated with the determination of an effective crack driving force for both Elber type and that of ...
S. STOYCHEV and, D. KUJAWSKI
openaire   +1 more source

Shielding of crack tips by inclined pileups of dislocations

Acta Metallurgica, 1988
Abstract A mathematical formulation is developed for a long crack (mode III) with two symmetrical screw dislocation pileups inclined to the crack by an angle φ. Dislocation free zones (DFZ) are allowed at the crack up. The resulting series of equations are solved numerically.
C.S. Pande, R.A. Masumura, Y.T. Chou
openaire   +1 more source

Crack tip shielding in elastic particulate composites undergoing damage

Engineering Fracture Mechanics, 1998
Abstract A simple rate-independent phenomenological constitutive model is used to model fracture behavior in elastic particulate composites undergoing damage. The constitutive model consists of two damage functions that govern the degradation of the bulk and the shear moduli.
G. Ravichandran, C.T. Liu
openaire   +1 more source

Crack Tip Shielding in 2090 Al-Li Alloy

1996
Thermal dependency of fracture toughness as a function of normal cracking and cold pre-stressing (CPS) conditions at the 173 K is studied in 2090 Al-Li alloy. It was found that fracture toughness increases with decreasing temperature for L-T orientation.
Arie Bussiba, Moshe Kupiec, Yosef Katz
openaire   +1 more source