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V. Veselý et alii, Frattura ed Integrità Strutturale, 25 (2013) 69-78; DOI: 10.3221/IGF-ESIS.25.11 75 P v is neglected, significant difference appears earlier, around  = 0.75 (see Fig. 6a and b, where comparison with [23], which ignores P v , is shown). (a) (b) (c) (d) Figure 4 : 2D representation of the WST – static scheme with indication of boundary conditions (a) and corresponding FE model (b) . Example of the FE mesh around the crack tip: ring of selected nodes (at radius 5 mm from the crack tip) (c) and quarter-point crack- tip elements (d) . 0 25 50 75 100 125 150 175 200 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 B 1 [-] α [-] platens I, P sp platens I, P sp + P v , 1 supp. platens I, P sp + P v , 2 supp. (1/4) platens I, P sp + P v , 2 supp. (1/8) platens II, P sp + P v , 1 supp. platens II, P sp + P v , 2 supp. (1/4) -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 B 2 [-] α [-] platens I, P sp platens I, P sp + P v , 1 supp. platens I, P sp + P v , 2 supp. (1/4) platens I, P sp + P v , 2 supp. (1/8) platens II, P sp + P v , 1 supp. platens II, P sp + P v , 2 supp. (1/4) (a) (b) Figure 5 : Geometry factors B 1 and B 2 as functions of the relative crack length  for various considered boundary conditions. -50 0 50 100 150 200 250 300 0.2 0.4 0.6 0.8 g 4 [-] α [-] 0.7 0.8 0.9 α [-] platens II, P sp + P v , 1 supp. platens II, P sp + P v , 2 supp. (1/4) distrib. load, P sp , 2 supp. (1/4) (ref. Karihaloo et al. 2003) -15000 -12500 -10000 -7500 -5000 -2500 0 2500 0.2 0.4 0.6 0.8 g 7 [-] α [-] 0.850 0.875 0.900 0.925 α [-] platens II, P sp + P v , 1 supp. platens II, P sp + P v , 2 supp. (1/4) Figure 6 : Shape functions g 4 and g 7 as functions of the relative crack length  for two support variants. An accurate knowledge of the mechanical fields in the cracked body is necessary for a relevant fracture analysis. As an example, a reconstruction of the stress fields in the WST (platens II, one support, P v considered) is introduced. Fig. 7 (a) (b) (c) (d)