Three-dimensional T-stresses for three-point-bend specimens with large thickness variation

Three-point-bend (3 PB) test specimens are useful for the systematic investigation of the influence of statistical and constraint loss size effects on the cleavage fracture toughness of a material in the ductile-to-brittle transition temperature range. Because the in- and out-of-plane elastic T-stresses (T-11 and T-33) are a measure of the crack-tip constraint and even the in-plane T-11 exhibits three-dimensional (3D) effects, the 3D T-stresses solutions were obtained by running finite element analyses (PEA) for 3 PB specimens with wide ranges of the crack depth-to-width ratio (a/W = 0.2-0.8) and the specimen thickness-to-width ratio (B/W = 0.1-40). The results show that the 3D T-11 at the specimen mid-plane tended to deviate from the 2D T-11 as B/W increased, with the deviation saturating for B/ W >= 2. The mid-plane T-33 increased with B/W and was close to the plane strain value vT(11) for B/W >= 2. (C) 2013 Elsevier Ltd. All rights reserved.