ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 5 June 2008
Page Count: 12

On the quantification of the constraint effect along a three-dimensional crack front

Wang, Xin
Associate Professor, Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Ontario

(Received 22 November 2007; accepted 2 May 2008)

Abstract

In this paper we examined the characterization of constraint effects for surface cracked plates under uniaxial and biaxial tension loadings. First, three-dimensional (3D) modified boundary layer analyses were conducted using the finite element method to study the constraint effect at a typical 3D crack front. The analyses were carried out using small geometry change formulation and deformation plasticity material model. Elastic-plastic crack front stress fields at a constant J and various T-stress levels were obtained. Three-dimensional elastic-plastic analyses were performed for semi-circular surface cracks in a finite thickness plate, under remote uniaxial and biaxial tension loading conditions. In topological planes perpendicular to the crack fronts, the crack stress fields were obtained. Then, J-Q and J-T two-parameter approaches are used in characterizing the elastic-plastic crack-tip stress fields along the 3D crack front. It is found that the J-Q characterization provides good estimate for the constraint effect for crack-tip stress fields. Reasonable agreements are achieved between the T-stress based Q-factors and the Q-factors obtained from finite element analysis.

Keywords:
elastic-plastic fracture mechanics, constraint effects, T-stress, Q-factors, surface cracked plate, biaxial loading

Paper ID: JAI101550
DOI: 10.1520/JAI101550
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