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 thick-ness plate, under remote uniaxial and biaxial tension loading conditions. In topological planes perpendicu-lar 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. Reason-able agreements are achieved between the T-stress based Q-factors and the Q-factors obtained from finite element analysis. Copyright

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Keywords Biaxial loading, Constraint effects, Elastic-plastic fracture mechanics, Q-factors, Surface cracked plate, T-stress
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Journal Journal of ASTM International
Wang, X. (2008). On the quantification of the constraint effect along a three-dimensional crack front. Journal of ASTM International, 5(6). doi:10.1520/JAI101550